Housing construction today is so diverse that sometimes the structures being built take on a completely bizarre fantastic look. In particular, architects love to experiment with a roof, which is made transparent, and in the form of tree foliage or a flower, and a skateboarding area - in general, their imagination is completely limitless. But we are somehow closer to simpler options, for example, a gable roof. We will talk about what it is and what the rafter system of a gable roof consists of in this article.

It is this type of structure that is most popular in the construction of residential buildings, since it creates a sufficient attic space that does not require additional insulation. In addition, a gable roof is not as difficult to install as, for example, a hipped roof, and also does not require huge investments for its installation.

A gable roof is a structure consisting of two rectangular planes connected to each other in the upper part, and to the walls of the house in the lower parts. The end part of such a building is usually erected from the same materials as the walls of the building, sometimes an entrance to the attic is also built here.

Recently, it has become very popular to build an additional room in the attic space, often used as a summer guest room. The installation of a gable roof rafter system and the subsequent insulation of the resulting room allow you to create a full-fledged room in which you can live both in summer and in winter.

All the advantages of gable structures

The main components of the rafter roof are the Mauerlat and the rafter legs, in addition, various struts, struts, crossbars, stops and battens help to make the structure strong and reliable. The drawing of a gable roof also includes a layer of insulation, vapor barrier, waterproofing and the roof itself. Thanks to all these elements, a gable roof has a number of advantages:

• simplicity of technical execution;
• low probability of leaks, since the structure is one-piece;
• high efficiency, because a relatively small amount of materials is spent on its construction;
• the possibility of arranging a full-fledged living area in the attic;
• ease of repair in case of defects;
• high strength and wear resistance.

The angle of inclination is an important component of a solid roof

The angle of inclination is determined depending on the weather conditions of the region of residence, on the characteristics of building materials and on architectural requirements.

For example, in areas where rainfall is normal, the roof is always made at a steep angle. This is necessary so that snow masses accumulate on its surface as little as possible, which can lead to the collapse of the building. In regions with the strongest winds, flat roofs are most often built, since the wind pressure on such structures is significantly reduced.

In whatever climatic zone the dwelling is located, the gable roof truss system cannot be built at an angle of less than 5 degrees!

Recommendations for calculating the area of ​​a gable roof

Calculation of the roof area - picture

The calculation is not as difficult as it might seem at first glance, but this painstaking process requires perseverance - all data must be double-checked at least three times. Agree, no one wants to spend money on building materials that are completely unnecessary for him.

In some cases, the measurement of the roof area can be complicated by some "obstacles", for example, the presence of an attic or an unusual shape of the roof - it is unlikely that it will be possible to do without the help of a specialist. We will consider the calculation of the area on the classic version of the roof with two slopes:

• First, we determine the length of each slope, it is equal to the distance between the lower edge of the ridge and the extreme point of the cornice;
• We take into account all the elements of the roof: parapets, overhangs, firewall walls and other structures that create additional volume;
• We decide on the type of roofing material for which we will calculate the area;

It should be borne in mind that in the case when the roof is covered with a roll or tile type of materials, the length of each slope will be less by about 0.7 m.

• Elements such as ventilation shafts, windows and chimneys are not taken into account;
• When, taking into account all the details, the area of ​​each slope is calculated, we calculate the slopes: the elements of the slopes are multiplied by the cosine of the roof slope angle, and the area is calculated only by the overhangs.

For the greatest convenience in calculating and obtaining correct data, it is best to calculate the area of ​​each element separately, and then add the resulting numbers.

The roof area was calculated, we decided on the roof - it remains only to understand in detail all the structural elements, such as rafters, Mauerlat, side / ridge girders, struts and braces, as well as diagonal ties, after which you can start calculating a specific type of rafter system.

Hanging and layered rafters

Of course, such a structure as a do-it-yourself gable roof rafter system appears in the minds of many as something very complex and time-consuming. But if you carefully consider the construction of such a structure and study the necessary material in advance, the question remains only in the "number of hands" that you will need for the construction process.

Let's start with the hanging rafters as part of the roof. These beams have only two points of support - walls, therefore the main loads acting on them are bending and compression. The weight of the roof, as well as the effect of snow and wind, is transmitted to the walls through the hanging rafters, so that this pressure is compensated, the rafters are connected with a tightening made of metal or wood. It can be positioned at any height, but the higher it is, the stronger and more durable it should be.

Sliding rafters are beams that have an intermediate support resting on the inner wall of the house. The main effect on such a structure is bending. The supporting structure of the roof is made only from layered supports, when the distance between them is not more than 6.5 m.

The same roof can consist of layered and hanging rafters at the same time: where there is an intermediate support, layered rafters are erected, and where not, hanging rafters.

Mauerlat and girders

The lower part of the rafters in houses built of timber rests on the upper crown, and in buildings made of brick or foam concrete - on a special timber called a mauerlat. For its installation, a waterproofing material is placed on the inside of the load-bearing wall, on which the Mauerlat lies. The length of the timber can be equal to the length of the building wall, or it can be adjusted to the size of each rafter leg - this is even more economical.

Ridge girder - a bar to which the upper parts of the rafters are fixed. That is, it is the ridge of the roof. Its length depends on the length of the roof, therefore, for its construction, both a solid massif and several logs are used.

Side girders are needed for additional support of the rafters, their emphasis is also placed on the gables of the building. The ends of such girders are sometimes extended beyond the gables, thus, unloading consoles are obtained, as a result, the roof pressure on the central part of the girder is significantly reduced.

If the roof of the building is erected from heavy materials, for example, from natural tiles, then the side girders are made in the form of a rocker arm, for this the logs are slightly suspended and bent.

A little more about the important elements of the roof

Diagonal slabs - picture

Additional diagonal slabs are called braces, with the help of which the rafter system of the gable roof is strengthened and the gables' wind resistance characteristics are increased. The upper part of the braces rests against the gables, and the lower part against the central floor.

The braces are necessary to reduce the load on the rafter legs, their installation at an angle of 45 degrees and higher can significantly reduce wind loads and the pressure of snow masses on the roof, therefore, in the northern regions of the country, such roof elements are simply irreplaceable.

If the roof consists of slopes of various areas, then the angle of their inclination will not be equal. Consequently, for the greatest strength of such a structure, vertical posts are erected in the places of "fracture", on which the side girders rest. Most often, such structures are built for attic rooms.

In areas characterized by a constant strong wind, roof systems must be reinforced with diagonal ties, which are boards, the thickness of which is from 25 to 50 mm. The bottom edge of the board is fixed to the heel of the rafter leg, and the top to the middle of the opposite rafters.

Correct calculation of materials for the gable roof truss system

Do not be afraid to independently make all the necessary calculations, because the dimensions of a gable roof, especially if it has the shape of an isosceles triangle, without deep mathematical knowledge can be calculated by any person.

So, consider the calculation of the gable roof rafter system using a specific example. The house, for which it is required to erect such a structure, has a width (W ir) 4m, a length of 6m, and the angle of inclination of the rafters (Y) should be equal to 120 degrees. The roof will be built of metal tiles, the distance between the rafters is planned to be 1 meter.

First, we find the height of the central support (C):

C = 0.5? W ir / tgY / 2 = 0.5? 4 / 1.73 = 1.2m

The length of the rafter leg (Ds) is calculated using the following formula:

DS = 0.5? W ir / sinY / 2 + 0.5 = 2.8m

0.5 in this formula is the allowance for the roof visor, it must be taken into account without fail!

Roof area (PC) = D? Ds? 2 = 33.6 m 2

It turns out that this is exactly the number of sheets of metal you need for the roof.

The distance between each batten (Pp) is conventionally taken as 35 cm, which means:

Crate length = Ds / Rp? D? 2 = 96 linear meters

With a house length of 6m and a distance between the rafters of 1m, we need 7 rafter legs, which means that the amount of timber for them and for the Mauerlat is no less than:

The length of the bar = (2? Ds + W ir + Ts) = 75.5 r.m.

The required amount of other materials is calculated in the same way. When all the calculations are done and the required amount of building materials has been purchased, we proceed to the direct construction of a gable roof.

We build a gable roof with our own hands

So, now we come close to such a moment as the installation of a gable roof truss system. This process begins with the construction of beams.

There are only two options for their installation:

• If the attic is not planned to be used as housing, then boards of size 50 are suitable for floors? 150 mm.
• To equip the attic, you will already need a bar with dimensions of 150? 150 mm, and each of them fits exactly on the load-bearing walls of the building. This is the only way to create a truly reliable and durable attic structure, only the cost of its construction will be an order of magnitude more expensive than the construction of an ordinary attic. But the living area of ​​the house will increase significantly - decide what is more important to you and think over everything to the smallest detail.

Floor beams are laid across the entire width of the building, leaving 500-600mm per ledge from the load-bearing walls - this will protect the wall from water flowing down from the roof slopes. Around the entire perimeter of the house, a board is laid on beams, which will become the basis for the racks of the walls of the second floor - the attic.

For the construction of all roof elements, the following fastening materials are used:

• screws,
• nails,
• self-tapping screws,
• dowels,
• wire,
• metal squares.

As soon as the racks are installed, you can start arranging the rafters.

Such a do-it-yourself gable roof rafter system is the simplest in technical performance. Why? Firstly, because it is not necessary to calculate the rafter device depending on the material and the location of the insulation.

And secondly, we do not need the dimensions of the section either.

The easiest way is to "tame" a gable roof of a regular triangular shape, because all its components will have identical dimensions.

In addition, this system has several more undeniable advantages:

• the cross-section of rafters and beams has a high margin for bearing capacity;
• this form is very reliable, since the load on the structure is evenly distributed, and the risk of deformation of the rafter legs disappears;
• the triangular rafter system is an independent structure, therefore, if there are malfunctions in other elements of the building, it remains intact;
• the beam, laid with a small overhang, also serves as a frame for the entire weight of the roof - and this is additional reliability of the entire building as a whole.

Attic rafter system

It will only be about a single-level attic, since it is quite possible to build it with your own hands. It is recommended to entrust the construction of more complex structures to experienced specialists, since it is easy to make a mistake in the calculations without their help, and the result will be disastrous.

A board is placed on the beam, from which the lower part is sawn off - this is done so that there were no gaps between the beams and the rafters.

A beam should be laid on a board (100 mm), a line should be drawn at the place of their joining. Then, along this line, the board must be sawed, as a result of which a beveled board should be obtained, which will fit snugly to all floor beams.

Again, along this line, we cut and so on. Performing these steps will ensure a tight and accurate fastening of the upper part of the rafter system, which can be installed. Using a lining, fasten each row of rafters at the top (on the ridge), in the end, fasten the resulting strapping with a special crossbar, which will act as a ceiling for the ceiling.

The rigidity of the structure being erected directly depends on how firmly the rafters will be fixed to each other. It is best to use special metal overlays - this way you can achieve the greatest roof strength.

When all the rows of rafters are fixed, you can start checking the correctness of the creation of the gables - they must be located strictly at right angles. Here the construction plumb line will come in handy - an indispensable thing for such situations.

When the correctness of the design does not cause any doubts, you can begin to capitalize all the parts with each other, soft wire, nails or staples will help in this.

Now you need to pull the string along the top of the gables, so it will be more convenient to install the middle rafters at a single level.

To exclude the possibility of sagging of the rafter system, it is necessary to strengthen the middle rafters with special struts.

The installation of struts usually does not cause any difficulties: the lower part of them is fixed to the attic post, and the upper part to the middle of the rafter leg, where you need to cut a groove of the required depth. To fix the structure, you need to choose nails from 200 mm.

That's all - the do-it-yourself gable roof rafter system is ready! It remains only to build the crate and cover the roof with a roof, but these are completely different technologies, which will be discussed in the next article.

21.02.2017 1 Comment

The rafter system of a gable roof is a simple design, available for a do-it-yourself device even for a novice developer. You just need to make preliminary calculations, familiarize yourself with the details and stages of roofing, calculate the materials needed for installation. When calculating, it should be borne in mind that the bearing capacity of a gable roof depends on the effect on it of loads from wind, snow, and the weight of materials.

In order for the process of building a gable roof rafter system to be given to you as easily as possible, below are detailed step-by-step instructions for installing the rafter system with your own hands.

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Requirements for building materials

For the device of the rafter system, the best option would be to use sawn timber from coniferous wood - pine, spruce or larch, I - III grade.

The material for the rafters is taken at least grade II, the Mauerlat is made from boards or timber of the II grade, for the racks and girders, the material is taken from the II grade, the lathing is made of lumber of the II-III grade, it depends on the roof. Crossbars, tightenings are made of Grade I material. On linings, linings, you can use grade III material.

Note! The lumber must be dry with a moisture content of no more than 20%. Before installation, it should be treated with fire retardants and antiseptics against fungal diseases.

You need to store lumber under a canopy, providing protection from the sun and moisture. Level the storage area, shift the lumber with spacers for ventilation.

For installation, you will need fasteners: ties, plates, pins, bolts with washers and nuts, self-tapping screws with EPDM gaskets, 2.8 mm thick, mounting tape, galvanized brackets.

Brackets are used when attaching the Mauerlat, fasten them with nails or self-tapping screws.

KR corners are used to attach the rafters to the Mauerlat, prevent the rafters from moving.

All fasteners must be made of high quality material and protected against corrosion.

Tools for the construction of the rafter system

To install the gable roof rafter system, you will need the following set of tools:

• tape measures of various lengths 5, 10, 20 meters;
• markers, pencils;
• cord for stretching;
• hammers, various purposes, nail puller;
• scissors for cutting;
• roofing knife;
• putty knife;
• Scotch;
• hacksaws, electric saw, electric drill with various drills and attachments;
• screwdriver with nozzles;
• markings, horizontal and vertical levels;
• slats, rulers;
• mounting foam;
• safety strap and rope - for safe work.

All tools on the roof should be kept in a tool bag for safety reasons.

Types of rafter systems for a gable roof

Sent rafters

They are supported by a Mauerlat and racks installed on the inner wall, with an equal pitch to the rafters. To give rigidity with spans of 6 m, braces are additionally installed.

Diagram of layered rafters of a gable roof

Hanging rafters

If the building is small in width, you can arrange a rafter system when the rafters rest on the Mauerlat or walls, without intermediate supports. The maximum span is 9 meters. Sometimes such roofs can be arranged without a Mauerlat. The rafters are installed on the wall, using spacers, on the rafters in this version, a bending moment acts.

To unload, wooden or metal plates are placed. They securely reinforce the corner. For hanging rafters of a larger span, a headstock and struts are installed. For hanging systems, the rafters are arranged with a larger section, and the lumber is chosen at least I II grade.

Diagram of hanging rafters of a gable roof

Calculation of the rafter system

You can determine the cross-section of a gable roof beam required in the rafter system by collecting all the loads acting on it: the weight of the coating, lathing, snow, wind pressure, precipitation.

Constant loads can be determined by the weight of 1 m 2 of roofing, lathing. It is important that the weight per 1 m 2 of the roof is in the range of 40-45 kg.

Variable loads from snow, wind are calculated according to the tabular values ​​of the SNiP normative documents, depending on the height of the building, the temperature zone. The load from the snow is equal to its weight multiplied by a factor depending on the slope of the slope. All these calculations are carried out in the project.

And if there is no project, and the roof is being erected on a small building? You need to look at the construction of a house in the neighborhood, which is being carried out according to a project, the roof area is the same as your building. The gable roof rafter system will serve as a model.

Sizes of timber for rafters

At the top point, a ridge is laid, which connects the rafters. The height of the ridge depends on the slope of the roof. The slope is influenced by the choice of coating material. The minimum dimensions are:

• for tile roofs, slate 22 gr .;
• for metal tiles - 14 g.;
• ondulin - 6 gr.;
• corrugated board - 12 gr.

The optimal angle is 35-45 degrees. slope, provides a quick discharge of water and snow. In regions with strong winds, the roofs are made flat and then the angle of inclination is within 20-45 degrees.

You can determine the height by the formula: H = 1 / 2Lpr * tgA. Where A is the angle of inclination, L is the width of the building.

The task is simplified when using a ready-made table. The coefficient depends on the width of the building and the angle of inclination. Factor multiplied by 1⁄2 the width of the building.

The rafters are made from pine or spruce bars, with a section of 50 × 100 mm, 50 * 150 mm.

The size of the rafters depends on the pitch. The step of the rafters is smaller, a larger number is installed, the section will decrease. The distance between the rafters at a gable roof is in the range from 600 mm to 1800 mm, it all depends on the structure of the roof and the materials used for its construction.

Rafters size table, depending on the step of their installation

Length rafters, mm	Distance between rafters, mm	The size of the cross-section of the rafter beam, mm
up to 3000	1200	80 × 100
up to 3000	1800	90 × 100
up to 4000	1000	80 × 160
up to 4000	1400	80 × 180
up to 4000	1800	90 × 180
up to 6000	1000	80 × 200
up to 6000	1400	100 × 200

The roof does not end at the level of the walls, it is extended outward by 500 mm. The rafter leg can protrude, or a board or block is built up. In this case, moisture does not get on the wall, the foundation is not poured.

Step-by-step installation of the gable roof truss system

The gable roof rafter system consists of the following elements:

1. Mauerlat.
2. Beds.
3. Racks.
4. Rafters.
5. Braces.
6. Puffs.
7. Lathing.

Mauerlat installation

Mauerlat fasteners to a monolithic reinforced concrete belt

Mauerlat evenly distributes the load on the walls of the building, its installation can be done in several ways:

• to be attached to the wall through a reinforced concrete belt with studs;
• studs are inserted into the masonry;
• a simple and common method for simple roofs, wire rod fastening.

For him, take a bar with a section of 100 × 100 mm, 150 × 150 mm or 200 × 200 mm. Which section to choose depends on the size of the roof and its coverage. The Mauerlat is joined along the length, for this, make a wash down of 100 mm, 500 mm long, fold the bars and fasten with pins.

In the corners, the Mauerlat is tied with cuts into the floor of the timber, fastened with staples or bolts. At wooden buildings, this is the Mauerlat, the last crown. On brick walls, make a monolithic reinforced concrete belt with a section of 400 × 300 mm. Along the waist, place pins with a thread of 12 mm in diameter, every 120 mm, for fastening.

Drill holes with a diameter of 12 mm in the Mauerlat, lay them so that the pins go into the holes. Tighten with nuts from above. First, we put two layers of roofing felt or roofing felt under the block. On the outside of the wall, lay the Mauerlat with a brick. Lay the Mauerlat on a horizontal and vertical base. It is necessary to check the level of the horizontal surface. Check the diagonals. Align with shims if necessary.

Installation instructions for beds, racks, rafters, struts and puffs

The device of the rafter system of a gable roof with your own hands is performed in the following order:

1. Install the bed, with the rafters sent.
2. Mark the step of installing the rafter legs.
3. Prepare to fit the rack.
4. Install them, if necessary, unfasten with spacers.
5. Lay the purlin. Check geometry. Install the hardware.
6. Try on the first rafter leg, mark the trim points.
7. Make a marking of the points and install the rafters at the beginning and end of the roof, pull a cord between them in order to align the rest of the elements along it.
8. Having installed the rafter leg, we first attach it to the Mauerlat, then to the ridge run, to each other.
9. Wire every other leg to the Mauerlat.

Fastening the rafters to the Mauerlat is done using cuttings, persistent corners and a hemming support bar. Reinforce with nails or staples.

Methods for attaching the rafters to the Mauerlat

Place the support legs on the beds or pads and strips. Lezhen is a beam of 50 × 100 mm or 50 × 150 mm, laid on the middle wall along a roofing felt gasket. Lay brick columns under the lining, 2 bricks high.

The rafter legs are connected to each other on a skate. Consider the common joints of the rafter system:

1. They make cuts at one leg and washed down at the other. Insert one leg into the cut with the other and fasten it with a bolt.
2. Install lining, wood or metal.
3. With the help of cuttings in the girder, they are fixed with nails or bolts.

Methods for connecting rafters on a ridge

For the stability of the roof to wind loads, puffs, struts and girders are installed. Tightening is a bar of 100 × 150 mm, purlins and struts are made of a bar of 50 × 150 mm or 100 × 150 mm.

With the installation of contractions, the reliability of the rafter structure increases. The cross-sections of the timber are the same with the rafters. Attached to the legs with bolts or nails. The device of struts adds rigidity to the structure. They are installed tightly, to the surface of the rafters.

The lumber has a standard length of 6 m. The rafters can be longer. Then you need to dock them. There are several ways to connect:

1. Fasten by putting the bars on both sides at the junction, connect them with nails in a checkerboard pattern.
2. Overlap, one part of the rafter to the other, at a distance of 1 meter, fasten with nails in a variable order.
3. Cut obliquely, cut out part of the rafter legs, connect them, fastening them with bolts.

Sheathing device

A crate is arranged along the roof rafters. It serves to distribute the load from the roofing material, snow onto the rafters. Plays the role of an air gap between the roof and the rafter system.

The design of the lathing depends on the adopted roofing material:

• under the soft tiles, the sheathing should be made solid, an anti-condensation film is laid on the rafters, the counter rail is pressed on top, the sheathing is nailed onto it, then OSB boards and a lining carpet, we put the tiles on the top.
• under the roof of the corrugated board, the crate should be sparse. The step of the lathing depends on the brand of the corrugated board, its thickness and the angle of inclination of the roof.
• the crate for standard slate should be made with a step of 500 mm from a bar of 75 × 75 mm or 50 × 50, as well as boards from 30 × 100 mm. The design features of the roof should be taken into account when making the final choice of a suitable option.

The lumber from which the crate is made is pine of the first or second grade. It is advisable to take the width no more than 14 cm. When the width is more, the boards can warp and damage the roofing. The length of the nails should be three times the thickness of the sheathing. Lay the boards along the ridge. Install the first board with a greater thickness to the height of the roofing.

Arrange a continuous crate along the roof slope.

With the first layer, lay a board along the ridge at a distance of 500-1000 mm from the next one, and so on. With the second layer, lay the crate along the rafters. Arrange the joint between the boards only on the rafters in a run. Insert the nail completely with the head into the pulp of the wood.

Eaves overhangs

They are installed to protect from atmospheric precipitation, play an aesthetic role. Eaves overhangs are arranged tightly without cracks. The final stage of roofing.

Diagram of the device for the eaves overhang of a gable roof

Gable

The gable roof has two gables. They have the shape of a triangle, with an apex at the ridge and the sides coincide with the roof slopes. The gables support the rafters and enclose the attic space. Protect from wind and precipitation, give stability to the roof.

In wooden buildings, the pediment is made frame. In brick buildings, frame or brick. The gables are made of brick or aerated block, erected before the roofing device. They require very precise execution.

The frame gables are inserted into the finished opening when the rafter system is already assembled.

The frame is made from bars or boards. The elements of the frame are connected on thorns or in the floor of a tree, all fastened with nails. Sheathed by nailing boards, lining or siding, maintaining the color scheme in the decoration of the facade of the building. For the device of a window opening, an additional frame is made for it according to the size of the window. If the attic is insulated, then the pediment also needs to be insulated. Insulation is laid in the middle of the frame. Mineral wool insulation with low combustibility is used. From the outside, the frame is upholstered with a hydro-windproof film or a windproof membrane, from the inside, a vapor-proof film or a vapor-proof membrane is nailed under the finishing material.

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The simplest gable roof is at the same time the most reliable. The availability of do-it-yourself execution does not give rise to self-confidence - before starting work, you need to thoroughly familiarize yourself with the design features in order to make decisions and execute them in a qualified manner.

Diagram and features of the gable roof device

A gable roof is called a roof formed by the intersection of two rectangular slopes at a certain angle. Such a device is the most reliable and simplest, therefore, even a person with average carpentry skills can independently mount a gable roof.

The base of the roof is a rafter system that acts as a support for the roofing cake and topcoat. The service life of the roof and the comfort of living in the house depend on its strength and reliability. The rafter system, subject to regular wind and snow loads, must be securely attached to the building body. This task is solved with the help of a Mauerlat, which is firmly fixed to the upper plane of the walls of the house. Thus, an almost monolithic system is created that reliably protects the internal space of the house from any manifestations of the external environment.

Photo gallery: how you can use the space under a gable roof

A residential attic can be arranged under a gable roof A gable roof with a Danish half-hip improves the exterior of the building and allows you to increase the size of the attic The attic above the garage can be used to store spare parts, set up a break room or equip a warehouse for household equipment The area of ​​the attic under a gable roof depends on the height of the ridge and the angle of inclination of the slopes

The structure of the gable roof truss system

A roof with two opposite slopes is the most common construction used in individual housing construction. The intersection line forms a ridge, and the side openings of the extreme rafter legs serve for the device of gables - vertically located walls that create a closed under-roof space. To obtain a strong and durable structure, many retaining and reinforcing elements are used, giving additional rigidity to the entire structure. The gable structure is based on a triangle - the most rigid geometric figure. The rafter system consists of the following main elements:

1. Mauerlat is a wooden beam that acts as a connecting element between the frame of the house and its rafter system. It is attached to the walls with threaded rods, anchor screws or wire harnesses. The size of the cross-section of the timber is from 100x100 to 150x150 mm and depends on the size of the building, its number of storeys and the shape of the roof.
2. Rafter leg - a wooden beam measuring 50x150 or 100x150 mm, connected at the top of the roof with the ridge and resting on the opposite end on the Mauerlat. Rafters are the main bearing element of the roofing system, which perceives all types of external loads: wind, snow, rain and the dead weight of the structure.

   Roof trusses form the load-bearing frame of the roof and determine its geometric shape

3. Lezhen - timber made of wood, laid horizontally with support on the internal load-bearing wall. The size of the bed, as a rule, is equal to the size of the Mauerlat. Supports roof racks.
4. Tightening is an element used in hanging rafter systems. Its purpose is to compensate for the tensile forces that occur at the lower ends of the rafter legs.
5. Racks - square beams that transfer part of the load from the rafters to the beds.
6. Struts are structural elements that transfer part of the load from the rafter legs to the tightening. Thus, a farm with increased strength characteristics is formed.
7. Counter lattice - wooden bars ranging in size from 25x50 to 50x50 mm, stuffed onto the upper edge of the rafters. The purpose of the counter-lattice is to form a ventilation gap between the lathing and the waterproofing film. This element is required when constructing a roofing pie in the attic.
8. Sheathing is a support base for installing a finishing roof covering. The sheathing can be solid or sparse and can be made of 25 mm thick boards, waterproof plywood, OSB sheets and other similar materials. The choice of lathing design depends on the characteristics of the topcoat.
9. A ridge is a horizontally located beam along which opposite slopes intersect.
10. Roof overhang - is a continuation of the rafters at a distance of up to 40 cm from the walls of the building. Protects walls from getting wet, and also serves to place spotlights, which are an integral part of the ventilation system of the under-roof space. With insufficient rafter length, the overhang is formed by additional parts for their lengthening - filly.

    The rafter system of a gable roof consists of triangular trusses, supported by a Mauerlat and a ridge, lathing and several auxiliary elements that reinforce the structure

Calculation of the load on the rafter system of a gable roof

The rafter system experiences certain loads, which can be divided into two types.

1. Constant loads acting independently of any other factors. Their size is determined by the design of the roofing pie and consists of the weight of waterproofing and vapor barrier films, insulation, additional elements, fasteners and any other elements of the roofing covering, including the finishing one. In practice, the average weight of all components of the roof of a house is about 40–45 kg / m 2. More precisely, this value can be calculated by summing the specific load values ​​of each material used, which can be taken from the look-up tables. When calculating the weight of the roof, it is recommended to lay a safety margin of 10%.

   When calculating the load, the weight of each element of the roofing cake is taken into account

2. Variable loads. These include the effects of wind and snow, depending on their intensity. In fact, the roof of the house is a sail that takes up the load from the wind. The force of direct impact on the roof along the normal depends on the angle of inclination of the slope - the smaller it is, the lower the load. At the same time, eddies arise on the leeward slope, and a load on the roof appears with an inverse impact vector. With hurricane winds, the separation force can reach 630 kg / m 2. Snow influences also belong to variable loads. It should be noted that they also have clearly defined regional indicators.

   Wind loads are a risk factor for roofs as they create large tearing and overturning forces.

Obviously, careful calculation of snow and wind loads, taking into account local climatic conditions, is vital when choosing a roof structure and materials. These loads can be determined from the map drawn up on the basis of SNiP 2.01.07–85.

The map can be used to determine the value of wind and snow load in the construction region.

The values ​​of snow and wind loads marked on the maps for each region are called normative. In order to obtain the calculated snow load, the standard value must be multiplied by a special coefficient that takes into account the angle of inclination of the roof. This coefficient is equal to:

• 1 with a slope of less than 25 o;
• 0.7 at an angle of inclination from 25 to 60 o;
• 0 for steeper slopes.

The calculated wind load is determined by multiplying the standard value by a factor that takes into account the height of the building and the type of terrain in which the construction is being carried out.

Table: Correction factor for calculating wind load (taking into account building height and type of terrain)

The specific load of the most popular roofing materials can be taken from the following table.

Table: Weights of some roof materials

It is possible to take into account the features of the impact of different types of loads only in aggregate, therefore, calculations of this nature should be entrusted to an experienced specialist.

Video: calculation of the rafter system

Types of gable roof truss systems

According to the principle of the device, rafter systems are of two types:

1. Hanging.
2. Forced.

Hanging rafters are used for buildings in which the bearing supports are located at a distance of up to 10 meters in the absence of an intermediate wall inside the building box. For other cases, it is necessary to use a layered rafter system.

Features of the device of the hanging rafter system

The hanging rafters are supported by the outer walls. Since the arch has a joint at the upper point, when vertical loads are applied to it, expanding loads are created on the lower supports. To compensate for them, puffs are used - horizontal ligaments between the lower ends of the rafter leg. The result is a rigid force triangle. When arranging an attic room, floor beams are used as a tightening. Various constructive solutions for the hanging rafter system are possible:

1. Simple three-articulated arch. It is a triangle-shaped structure. In this case, the tightening works only in tension and is not a supporting one. Therefore, it can be replaced with a conventional metal beam. In this case, the connection of the cornice joint is performed with a simple orthogonal cut using wooden plates or metal plates.

   The three-pivot arch is the simplest truss structure for a gable roof

2. Reinforced three-articulated arch. This scheme was used earlier in the construction of industrial buildings, when the span exceeded 6 meters. In this case, the tightening is suspended on a wood headstock. The assemblies are connected using metal parts and equipped with devices for adjusting the tension. The main load in such a system falls on the ridge of the roof. In individual housing construction, such rafter systems are not used.

   A three-articulated arch with reinforcement differs from a simple one by the presence of a vertical stiffener (headstock) and the ability to adjust the tension at the joints

3. Hinged arch with a raised latch. In this version, the rafter leg is partially unloaded through the roof ridge by the suspension to the raised puff. It rises to a height of at least 2.2 m from the attic floor level. Such a system is ideal for the construction of an attic room in the under-roof space. The connection of the tightening with the rafters is made by a tie-in, as a result of which the connection in the unit becomes fixed.

   A hinged arch with a raised latch is ideal for installing an attic under-roof space

4. A three-pivot arch with a deadbolt is used to strengthen the rafter system by creating an additional power triangle. The system is used for significant bursting loads. The connection of the crossbar to the rafter must be fixed, otherwise the entire system will not have the required rigidity.

   An additional horizontal element (transom) gives the system greater resistance to bursting loads

The crossbar, in contrast to the lower tightening, operates in compression, not tension.

In addition to those listed, other elements are also used to strengthen the roofing skeleton. Very popular are struts and struts located in the system at the places where the rafters are most loaded.

In the most loaded places, roof trusses can be reinforced with struts and struts

Video: rafter system step by step

Roof systems of the layered type

Reinforced rafters are used for buildings with a width of more than 10 meters. They are characterized by the presence of a load-bearing wall inside the building, which is an additional support for the rafter system. Nesting structures are of several types:

In non-expansion layered systems, the main load from the roof frame is transferred to the Mauerlat

Determination of the pitch of the rafters of a gable roof

The task of ensuring sufficient strength of the rafter system is solved by selecting the material for the manufacture of its elements and calculating the parameters of their installation. The pitch of the rafters is one of these elements and is selected depending on the weight of the roofing cake. The distance between the support beams is usually set in the range of 0.6-1.5 m. The actual pitch between the rafters depends on the geometry of the roof and is calculated as follows:

1. The number of rafter legs is determined. To do this, you need to use the ratio n = L / d 1 + 1, where n is the number of rafter legs, L is the length of the roof along the ridge, d 1 is the desired distance between the rafters.
2. The calculated distance between the rafters is calculated, for which the length of the roof along the ridge is divided by the amount obtained in the previous paragraph: d = L / n.

For example, consider an option with a roof length of 13 m with a preferred distance between rafters of 750 mm (option for a roof with ceramic tiles).

1. The number of rafter legs n = 13000/750 +1 = 18.33. Since the number of rafters must be sold in whole, round this value to 19.
2. The rafter pitch d = 13000: 19 = 684 (mm).

Thus, on the roof we have chosen, the rafters must be installed with a pitch of 68.4 mm.

It should be remembered that the result obtained is the distance between the axes of the rafters.

Gable roof truss system units

We have already discussed the main types of joints in the nodes of the roof supporting structure above. But it makes sense to dwell in more detail on the auxiliary materials that make the rafter system more reliable and durable.

You can strengthen the fastening of parts when installing the rafter system using metal plates and corners of various shapes

Such products are made of galvanized steel up to 1.5 mm thick. They have various configurations and can be installed on any kind of connection.

Photo gallery: types of connections in the nodes of the rafter system of a gable roof

In the ridge part, the rafter legs are usually connected by flat bolted plates To strengthen the structure of the rafter system, it is necessary to select metal plates that correspond to the configuration of the fastening unit Sliding knot mates relieve the rafter structure Junction points in the rafter system can be additionally reinforced with metal inserts Depending on the type of rafter system used, there are different ways of attaching the ridge knot On flat joints operating under heavy loads, it is convenient to use nail plates

All docking nodes of the rafter system have the function of strengthening the rafters by redistributing the loads and strengthening the bearing elements. So, in the lower part, the rafter is supported on the Mauerlat at a right angle, for which the corresponding inserts are made.

To strengthen the rafter system, they try to use connections with the maximum bearing capacity, for example, cutting the rafters into the Mauerlat at a right angle

In addition, metal mounting plates are used for additional reinforcement in the docking points. The same principle is used when installing struts to the rafters. In any case, the mating parts must work "on the stop" and not move during operation.

Any parts must be loaded along their axis

There are three main types of nodes in the rafter system:

1. Ridge connections. This is the joining of two rafter legs at a given angle along the line of intersection of the slopes. They can be hinged or blind. The first ones are used when installing a rafter system on log or log houses, which tend to sag and rise, depending on the season, during almost the entire service life. Blind joints are used in the truss systems of houses made of building stone. In such structures, a reinforced belt is installed on top of the wall, which takes on the lateral loads.
2. Fastening the lower ends of the rafter legs to the Mauerlat. Since they are at an angle to the support bar, a sliding vector is created that is directed outward from the structure. To compensate for it, a tie-in is made in the Mauerlat, and a heel is made on the rafter. The rafter is inserted into the groove with an emphasis on it and is fastened with a nail through the edge of the beam into the Mauerlat. Additional support parts made of bars are also used. In cases where the rafter has to move (on wooden log cabins), sliding fasteners are used. They make it possible to compensate for seasonal changes in the height of the walls.
3. Other nodes. All other parts of the rafter systems are essentially stubborn elements working in compression, rarely in tension. They are installed by cutting into the mating parts to prevent them from displacement under load. Such details include crossbars, struts, struts, stops and other similar parts.

For a stronger connection, the additional elements mentioned above are used.

Installation of a gable rafter system

Currently, the construction market offers services for the manufacture of individual roof trusses for specific buildings. It should be noted that this service has a number of advantages:

1. Guaranteed product quality, ensured by the use of special equipment and assembly technologies.
2. Fire safety, since all truss parts are flame retardant.
3. Longer service life, which is achieved by antibacterial treatment of products with special compounds.
4. Easy to install ready-made trusses.

The only drawback of this method of installing a rafter system is the relatively high cost of products.

For self-erecting a gable roof, you can use ready-made roof trusses ordered from professional manufacturers

Assembling roof trusses on the ground

The assembly of rafters on the ground is used in cases where there is a flat area of ​​sufficient size right next to the house for the manufacture of trusses. In this case, not complete trusses are mounted, but rigid structures of three or four parts, which can be lifted to the installation site by the efforts of two or three people. Lifting is carried out with the help of ropes along the slopes. The advantage of this assembly method is the possibility of using a single template, which ensures high precision in the manufacture of each structural element. A possible option for partial installation of trusses below is as follows:

1. Make a slipway for assembling trusses. It consists of three platforms, the distance between which corresponds to the length of the mating parts. They can be assembled from several boards or beams located in one horizontal plane.

   For the convenience of assembling the rafter frame on the ground, you need a free area of ​​a certain size and auxiliary elements on which you can place structural details

2. To assemble the first truss, you need to take two rafter legs and a tightening - lower or upper.
3. Having laid out the parts on the slipway, place them in accordance with the truss drawing and fasten them with nails. Check the truss blank for compliance with the dimensions specified in the technical documentation. Correct the location of the components if necessary.
4. Carry out the final fixation of the parts in the truss nodes using additional fixing plates. The nail plates can be installed using a power clamp, using additional heavy plate shims under its jaws.

   The power clamp allows you to pre-tighten the nail plates, and then fix them in any convenient way

5. Lay the details of the second truss on top of the first and fix with clamps, exactly following the contours of the lower truss, which acts as a template. After assembling the second truss, move it to the side.
6. Make the required number of trusses by repeating the operations from the previous paragraph. This ensures full compliance of all manufactured trusses.

   When making trusses according to one template, they will exactly repeat the size and shape of each other.

Installation of the rafter system at the installation site is as follows:

1. The first two trusses rise to the roof. To do this, you can use an inclined deck of several beams and fairly strong ropes.
2. The first to install gable trusses at the ends of the roof. They need to be set strictly vertically and fixed to the Mauerlat with temporary jibs.

   Gable trusses need to be installed first

3. A construction cord is stretched between the gable trusses perpendicular to the location of the rafter legs.
4. Each subsequent truss is installed in compliance with the previously calculated rafter pitch.

   In order for all trusses to be installed evenly, twine is pulled between the extreme structures

5. After the installation of the last truss, the entire structure of the rafter system is reinforced with girders, after which the temporary fasteners are dismantled.
6. Further, the rest of the structural elements are mounted - jibs, ridge beams, beds, racks, etc., provided for in the project of the rafter system.

The lathing, which is stuffed last, gives additional strength to the roof.

Assembling the rafter legs directly at the installation site

On-site rafter assembly is used on small roofs. At the same time, billets are fed upward, from which the necessary parts are cut. Installation is carried out from the bottom up, starting with the installation of the rafter legs. The horizontal level of the rafter system is controlled by stretched cords, and the verticality of the truss assembly is controlled by a construction plumb line. The installation procedure is the same: first, gable trusses are mounted, then the rest in any convenient order.

The assembly of the rafter system directly on the roof begins with the installation of racks and a ridge girder on which the rafters are laid

Accurately following the requirements of the drawings, you can mount the rafter system yourself. It is almost impossible to do this alone, so the participation of one or two assistants is mandatory.

Video: installing rafters with your own hands

When assembling a rafter frame for a gable roof, it is important to adhere to certain rules:

1. All wood used for the installation of the truss system must be treated with antiseptic and fire-fighting compounds.
2. When working with a hand-held power tool, the safety requirements specified in the instructions must be observed.
3. Installation of nail plates cannot be done by hammering in, this leads to their deformation. A clamping tool must be used during installation.
4. A waterproofing layer must be laid under the Mauerlat. Roofing material is traditionally used for this.
5. When installing the rafter system, you must use fasteners with a protective coating.
6. Installation of the rafter system should be done in dry, calm weather.

Video: gable roof for metal tiles

Like any roofing system, a gable roof requires careful and responsible attitude. Mistakes in the construction of such roofs are usually costly. Not only a careful selection of materials is important, but also their competent use. Nevertheless, the main part of the work can be done independently. I wish you success!

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Step-by-step installation of a gable roof - DIYer's guide

Professionals consider the gable system to be the simplest and most affordable, this is partly true, but for a home craftsman, self-assembly of a roof of any configuration can be a problem. Therefore, further we will analyze step by step all the stages of the construction of a gable structure, starting with professional terminology and ending with the arrangement of the roofing pie.

Basic concepts and subtleties

Before you go to the store for material and try to do something with your own hands, it will be useful to figure out what exactly you want, because there are several types of gable systems. And in order to compose an elementary project, you need to know the basic principles and terminology.

What and how is it called

• Mauerlat- this is a bar that serves as a support for the rafter legs and is mounted along the perimeter of the outer load-bearing wall. The minimum section of such a bar is 100x100 mm. It can be monolithic or type-setting, that is, it consists of 2 bars of a smaller section;
• Rafter leg- this is an inclined beam with the lower side resting on the Mauerlat, and the upper connection of such beams forms a ridge, in a gable system there are 2. The minimum thickness of the rafter leg is 50 mm. The width of the beams can be from 150 mm and more;
• Farm- the connection of two rafter legs (triangle), called a truss. The number of trusses depends on the length of the structure, the minimum pitch of the trusses is 600 mm, the maximum is 1200 mm. The choice of step depends on the weight of the roofing cake, as well as on what the snow and wind load is in the area;
• Ridge- the upper line of the connection of the rafter legs and two planes of the roof, it is also called the ridge run;
• Filly- overhangs from the edge of the rafter leg to the outer load-bearing wall. A frontal board is stuffed on the front side of the overhang, which often serves as a support for the installation of roof drainage gutters;

• Racks- vertical supports, which take on a significant part of the weight of the rafter structure. In small houses, the rack is placed only in the center, and supports the ridge. With significant roof sizes, as well as in houses with a residential attic, intermediate racks are mounted;
• Braces- small beams, which are mounted at an angle and provide additional stability for roof trusses;
• Tightening- a horizontal beam, pulling together 2 adjacent rafter legs. It can also be called a fight or a crossbar;
• Sill- this is to some extent an analogue of the Mauerlat, only here the beam is mounted on top of an internal load-bearing wall or several internal walls;

• Lathing- boards stuffed on top, perpendicular to the rafters. The lathing can be solid and with gaps, it all depends on the weight and device of the roofing cake;
• Run- an analogue of a ridge beam, but ordinary purlins are mounted over the entire plane of the roof, they strengthen the trusses and serve as additional support for the rafter legs.

Types of gable structures

Illustrations	Explanations
	Symmetrical system. The symmetrical rafter system is considered the most reliable and easiest to install. The loads are evenly distributed here, so the thickness of the roofing cake does not play a big role.
	Asymmetric system. Asymmetry is good not only for its original appearance, it is easier to equip a living space under such a roof. But, at the same time, much more calculations will be required, because the loads on the base and the roofing cake differ greatly.
	Broken roof. Formally, there are already more than 2 slopes in such a roof, but the installation procedure for broken and classic structures is similar. Therefore, they are united in one direction.

What is the difference between layered and hanging systems

If the distance between the outer walls does not exceed 10 m, and there is no major wall inside the house, then hanging rafters are installed. They rest on the Mauerlat and are pulled together at the bottom by ceiling beams, plus, in some cases, additional transverse tightenings are mounted.

Installation of layered rafters can be carried out only if there are capital walls inside the house. At the same time, the size of the building does not matter much. The overhead system is much more practical and durable, because the partition takes on a significant part of the total load.

A few words about calculations

When calculating any roof, 3 main components are taken into account - these are constant, variable and special loads.

1. Permanent loads include, first of all, the weight of the roofing and the rafter system itself. In unheated attics, this weight often does not exceed 30 kg per 1 m², and if you equip a full-fledged roofing pie with insulation, then here the weight can reach up to 50 kg;

1. The variables include snow and wind loads. To calculate, you need a wind rose and an average rainfall for the region. Here SNiP 2.01.07-85 will help you, according to which in Russia the snow load ranges from 80 to 320 kg / m². Both snow and wind loads are multiplied by a coefficient depending on the angle of inclination of the roof, and this coefficient is constant;

If your gable roof has an angle of inclination equal to or greater than 60º, then the snow load can be ignored, the snow does not stay on such a roof. But the wind pressure is much higher here.

1. Particular pressures include natural disasters such as earthquakes and hurricanes. Fortunately, there are not many such places in our country, so they are rarely taken into account in the calculations. Below in the video in this article, detailed instructions for calculating the roof are given.

Stages of installation of a gable roof

The entire installation can be divided into Mauerlat fastening, then the rafters, racks and struts are laid, and everything ends with the arrangement of the roofing pie.

How the Mauerlat is mounted

Mounting the Mauerlat, first of all, depends on what material your house is built from. So if the house is brick or made of cinder block, then a couple of layers of roofing material are rolled out over the wall and the Mauerlat bar is screwed on top with anchor bolts or any other studs.

With houses made of aerated concrete (foam or aerated concrete), everything is a little more complicated. Neither the anchor bolt nor the stud in such a block will hold, therefore, a reinforced concrete belt is poured around the entire perimeter of the wall, into which iron studs are initially embedded under the Mauerlat mount.

In wooden houses, the rafter system is mounted without a Mauerlat at all, more precisely, the upper beam plays the role of the Mauerlat.

Rafter legs in wooden houses are connected to the upper beam (Mauerlat) on a sliding principle, that is, not rigidly. This installation allows the rafters to move when the house shrinks.

We mount a simple truss system

Illustrations	Recommendations
	Mauerlat. In this case, the installation of the Mauerlat was performed on a built-in threaded pin, the pin is locked from above through the washer. Plus, for strength, they drove an anchor bolt.
	Extreme farms. To keep the outer trusses in the desired position, they were bolted in the center and additionally secured with struts and struts. These racks are needed only during the installation of the rafter system, then they are dismantled.
	Connection of rafters with Mauerlat. Stage 1. Vertical racks are installed first on the Mauerlat. They are cut from the same timber as the rafter legs. The extreme racks are fixed with two corners, 8 self-tapping screws in each, and the middle ones are fixed in the same way, only with 1 corner.
	Stage 2. On the reverse side of the rafter leg, exactly the same rack with a corner is installed. The rafter leg itself is connected to the racks with long self-tapping screws and through pins with a diameter of 12 mm.
	Stage 3. On the extreme farms, in addition to mounting on the Mauerlat, intermediate racks are also installed (they are not subsequently removed).
	Stage 4. A triangle is rigidly attached between the two racks holding the rafter legs on the Mauerlat.
	Ridge run. Stage 1. The ridge bar must run exactly under the connection of all trusses. To fix this beam on the outer farms, 2 puffs were installed, and the beam itself was screwed to the puffs with corners. Bars of this section are usually 6 m long, therefore, if necessary, they are increased. To make the connection strong, we attached the same bars on both sides and pulled all 4 with 12 mm pins.
	Stage 2. For reliability, the connections of the rafter legs were tightened with metal overlays on 6 studs 12 mm, 3 studs in each beam. If there are not enough pads with pins for each truss, then pull off at least the extreme ones, and fix the rest on both sides with plates for self-tapping screws.
	Puffs on extreme farms. On the extreme trusses, the puffs are installed inward, between the rafter legs and are fixed on both sides with metal plates.
	Tightening on intermediate trusses. Two puffs are placed on the intermediate trusses, they are applied on both sides and pulled together with two studs (12 mm) and four self-tapping screws.
	Reference point. In order to set the intermediate trusses in one plane, immediately after the installation of the extreme trusses, a cord is pulled between them and the rest of the trusses are mounted along it.
	Rafter cut. In order for the rafter legs to lean more firmly on the Mauerlat, triangular cutouts are made in them. But such cuts are made only in block houses, in wooden houses there are no cutouts, there the rafters should slide.
	Filly. From the edge of the rafter leg to the wall, there should be at least 30 - 40 cm. In this case, 50 cm was made. A 10 cm tolerance was left for insulation and siding of the walls.
	Rafter system - the result. We got a lightweight hanging-type rafter system. We did not put the central pillars, so the attic can be made living. Puffs on medium farms are paired, and on extreme ones, single. A single ridge bar runs at the top of the trusses. Since the system is hanging, the rafter legs are double reinforced.

There is one more important point: in wooden houses, in addition to the sliding attachment of the rafter legs to the Mauerlat, it is advisable to make the ridge connection also movable. The easiest way is to fasten metal plates on both sides of the rafter leg and “sew” these plates with a central pin, as in the photo below.

How a roofing pie works

The scheme of the roofing pie on all pitched roofs is similar, but the installation technology and the sequence of actions may be slightly different. If there are enough funds for a quick arrangement, then the pie is mounted from the bottom up and the entire roof is made in a maximum of a week. But if the house is being built gradually, then they act differently.

With limited financial resources, you can first equip a roof for a cold attic, and then (when money and time appear) you can insulate everything with your own hands.

To begin with, a vapor barrier is mounted on top of the rafter system. The rolls are rolled out perpendicular to the rafters and cover each other from bottom to top. As the roll is rolled out, the membrane is nailed to the rafters with counter battens (50x50 mm), and on top of these bars the main batten is stuffed.

After the first roll is unrolled and secured, the next roll is rolled on top of it with an overlap of 150 mm. After that, it is also fixed with a counter lattice, on which the lathing is stuffed. It is not worth measuring the overlap of the next roll, there is a line on it for this.

The pitch of the roof lathing can be different, for example, the slats are packed under the metal tile with a gap of about half a meter, and if you have ceramic tiles, then you need to focus on the size of the plates.

It is also easy to insulate the roof from the inside. Mineral wool slabs are simply inserted from below between the rafters. Further, the insulation is hemmed with another membrane, on which you can already sew on the final finishing of the attic.

If you prefer soft bituminous shingles, then the diagram below gives step-by-step instructions for arranging it.

Conclusion

A gable roof is a good choice for a novice DIYer. I tried to highlight the main stages and subtleties of its arrangement. If you still have questions, write in the comments, I will try to help.

October 9, 2017

If you want to express gratitude, add clarification or objection, ask the author something - add a comment or say thank you!

At the heart of each roof is a large number of beams, rafters, uprights and purlins, which are collectively referred to as the rafter system. Over the centuries-old history of species and methods of its organization, a lot has accumulated, and each has its own characteristics in the construction of nodes and cuts. We'll talk in more detail about what the rafter system of a gable roof can be and how the rafters and other elements of the system should be attached.

The structure of the gable roof truss system

In section, the gable roof is a triangle. It consists of two rectangular inclined planes. These two planes are connected at the highest point into a single system by a ridge bar (run).

Gable roof scheme

Now about the components of the system and their purpose:

• Mauerlat - a beam that connects the roof and walls of the building, serves as a support for the rafter legs and other elements of the system.
• Rafter legs - they form the inclined planes of the roof and are the support for the lathing under the roofing material.
• Ridge girder (bead or ridge) - unites two roof planes.
• Tightening is a transverse piece that connects opposing rafter legs. Serves to increase the rigidity of the structure and compensate for bursting loads.
• Beds are bars located along the Mauerlat. Redistribute the load from the roof.
• Side Girders - Supports the rafter legs.
• Racks - transfer the load from the girders to the benches.

Filly may still be present in the system. These are boards that lengthen the rafter legs to form an overhang. The fact is that to protect the walls and foundations of the house from precipitation, it is desirable that the roof ends as far as possible from the walls. To do this, you can take long rafter legs. But the standard length of lumber of 6 meters is often not enough for this. Ordering a non-standard is very expensive. Therefore, the rafters are simply grown, and the boards with which they do it are called "filly".

There are quite a few constructions of truss systems. First of all, they are divided into two groups - with layered and hanging rafters.

The difference in the design of the layered and hanging rafters

With hanging rafters

These are systems in which the rafter legs rest only on the outer walls without intermediate supports (load-bearing walls). For gable roofs, the maximum span is 9 meters. When installing a vertical support and a system of struts, it can be increased up to 14 meters.

The hanging type of gable roof rafter system is good because in most cases there is no need to install a Mauerlat, and this makes the installation of rafter legs easier: you do not need to make cuts, it is enough to mow the boards. To connect the walls and rafters, a lining is used - a wide board, which is attached to studs, nails, bolts, and crossbars. With such a structure, most of the bursting loads are compensated, the impact on the walls is directed vertically downward.

Types of rafter systems with hanging rafters for different spans between load-bearing walls

Gable roof rafter system for small houses

There is a cheap version of the rafter system when it is a triangle (photo below). Such a structure is possible if the distance between the outer walls is no more than 6 meters. For such a rafter system, you can not do the calculation by the angle of inclination: the ridge must be raised above the puff to a height of at least 1/6 of the span length.

But with this construction, the rafters experience significant bending loads. To compensate for them, either rafters of a larger section are taken or the cut of the ridge part is made so as to partially neutralize them. To give greater rigidity in the upper part, wooden or metal strips are nailed on both sides, which securely fasten the top of the triangle (also see not the picture).

The photo also shows how to extend the rafter legs to create a roof overhang. A cut is made, which should go beyond the line drawn up from the inner wall. This is necessary in order to displace the notch and reduce the likelihood of the rafter breaking.

Ridge knot and fastening of rafter legs to the backing board with a simple system version

For mansard roofs

The option with the installation of a crossbar is used when organizing a living room under the roof - an attic. In this case, it is the basis for filing the ceiling of the room below. For reliable operation of this type of system, the crossbar cut must be non-hinged (rigid). The best option is semi-rotten (see the picture below). Otherwise, the roof will become unstable to loads.

Raised gable roof rafter system and girder notch assembly

Please note that a Mauerlat is present in this scheme, and the rafter legs should extend beyond the walls to increase the stability of the structure. To fix them and dock with the Mauerlat, a cut is made in the form of a triangle. In this case, with an uneven load on the slopes, the roof will be more stable.

With such a scheme, almost all the load falls on the rafters, therefore they must be taken of a larger section. Sometimes the raised tie is reinforced with a suspension bracket. This is to prevent it from bending if it supports the ceiling sheathing materials. If the tightening is short, it can be secured in the center on both sides with boards nailed to the nails. With a significant load and length, there may be several such belayings. In this case, too, planks and nails are enough.

For large houses

With a significant distance between the two outer walls, a headstock and struts are installed. This design has high rigidity, since the loads are compensated.

Gable roof rafter system for a large span and cuttings for ridge and rafters

With such a long span (up to 14 meters), it is difficult and expensive to make an integral tightening, therefore it is made of two beams. It is connected with a straight or oblique cut (figure below).

Straight and oblique notch for tightening connection

For a secure fit, the joint is reinforced with a bolted steel plate. Its dimensions should be larger than the dimensions of the cut - the extreme bolts are screwed into solid wood at a distance of at least 5 cm from the edge of the cut.

In order for the circuit to work normally, it is necessary to make the braces correctly. They transmit and distribute part of the load from the rafter legs to the tightening and ensure the rigidity of the structure. Metal pads are used to reinforce the connections.

Attaching the struts for the truss system with hanging rafters

When assembling a gable roof with hanging rafters, the cross-section of lumber is always larger than in systems with layered rafters: there are fewer load transfer points, therefore, each element has a large load.

How the attic roof is arranged (with drawings and diagrams) read here.

With layered rafters

In gable roofs with layered rafters, their ends rest on the walls, and in the middle part they rest on load-bearing walls or columns. Some schemes burst the walls, some don't. In any case, the presence of a Mauerlat is required.

The simplest version of layered rafters

Spreader-free schemes and cutting units

Houses made of logs or beams do not respond well to spacer loads. For them, they are critical: the wall can fall apart. For wooden houses, the rafter system of a gable roof must be non-thrustable. Let's talk about the types of such systems in more detail.

The simplest spreader-free diagram of the rafter system is shown in the photo below. In it, the rafter leg rests on the Mauerlat. In this version, it works for bending without bursting the wall.

Simple spreadless gable roof system with layered rafters

Pay attention to the options for attaching the rafter legs to the Mauerlat. In the first, the support area is usually beveled, while its length is no more than the cross-section of the beam. The depth of the cut is no more than 0.25 of its height.

The top of the rafter legs is laid on the ridge beam, without fastening it to the opposite rafter. The structure turns out to be two pitched roofs, which in the upper part adjoin (but do not connect) one to the other.

It is much easier to assemble the version with rafter legs fastened in the ridge part. They almost never give space to the walls.

Option for attaching rafters without spacer on the walls

For this scheme to work, the rafter legs at the bottom are attached using a movable joint. To secure the rafter leg to the Mauerlat, one nail is hammered from above or a flexible steel plate is placed from below. See the photo for the options for attaching the rafter legs to the ridge girder.

If the roofing material is planned to be used heavy, it is necessary to increase the bearing capacity. This is achieved by increasing the cross-section of the elements of the rafter system and strengthening the ridge assembly. It is shown in the photo below.

Reinforcement of the ridge knot for heavy roofing material or with significant snow loads

All of the above gable roof schemes are stable in the presence of uniform loads. But in practice, this practically does not happen. There are two ways to prevent the roof from sliding towards a higher load: by installing a scrum at a height of about 2 meters or with struts.

Variants of rafter systems with scrapes

Installation of scrapes increases the reliability of the structure. In order for it to work normally, in the places where it intersects with the drains, you need to fasten it to them with nails. The cross-section of the timber for the fight is used the same as for the rafters.

Diagrams of gable roof truss systems with skirmishes

Attached to the rafter legs with bots or nails. Can be installed on one or two sides. See the figure below for attaching the scrum to the rafters and ridge girder.

Attaching the scrum to the rafter legs and ridge bar

In order for the system to be rigid and not "crawl" even under emergency loads, it is sufficient in this version to provide a rigid fastening of the ridge bar. In the absence of the possibility of its displacement horizontally, the roof will withstand even significant loads.

How to make a gable roof (photo report) read here.

Systems of layered rafters with struts

In these options, for greater rigidity, rafter legs are added, which are also called struts. They are installed at an angle of 45 ° to the horizon. Their installation allows you to increase the length of the span (up to 14 meters) or reduce the cross-section of the beams (rafters).

The brace is simply placed at the required angle to the beams and nailed from the sides and bottom. An important requirement: the brace must be cut accurately and fit tightly to the uprights and rafter leg, excluding the possibility of its deflection.

Systems with rafter legs. Above the spacer system, from the bottom - non-spacer. The nodes of the correct felling for each are located next to each other. Below - possible schemes for attaching the strut

But not all houses have the middle load-bearing wall in the middle. In this case, it is possible to install struts with an angle of inclination relative to the horizon of 45-53 °.

Off-center vertical purlins rafter system

Strut systems are necessary if significant uneven shrinkage of the foundation or walls is possible. Walls can sit in different ways on wooden houses, and foundations on layered or heaving soils. In all these cases, consider the device of this type of rafter system.

System for houses with two internal load-bearing walls

If the house has two load-bearing walls, install two truss beams, which are located above each of the walls. Benches are laid on the intermediate bearing walls, the load from the rafter beams is transferred to the benches through the racks.

Systems with truss beams

In these systems, the ridge girder is not installed: it provides thrust forces. The rafters in the upper part are connected to one another (cut and docked without gaps), the joints are reinforced with steel or wooden lining, which are nailed.

In the upper non-thrust system, the tightening force is neutralized by the tightening. Please note that the tightening is placed under the purlin. Then it works efficiently (top diagram in the figure). Stability can be provided by uprights, or jointing - beams installed obliquely. In the spacer system (in the picture it is at the bottom), the cross member is the crossbar. It is installed over the purlin.

There is a variant of the system with racks, but without the rafter beams. Then a stand is nailed to each rafter leg, which rests on the intermediate load-bearing wall with the second end.

Fastening the rack and tightening in the rafter system without a rafter girder

For fastening the uprights, 150 mm nails and 12 mm bolts are used. Dimensions and distances in the figure are in millimeters.

Rafters perform a number of significant roofing functions. They set the configuration of the future roof, perceive atmospheric loads, and hold the material. Among the rafter duties, the formation of flat planes for laying the coating and providing space for the components of the roofing pie. In order for such a valuable part of the roof to flawlessly cope with the listed tasks, information is needed about the rules and principles of its construction. The information is useful both for those who construct the gable roof rafter system with their own hands, and for those who decide to resort to the services of a hired team of builders.

Roof rafters for gable roofs

In the device of the rafter frame for pitched roofs, wooden and metal beams are used. The starting material for the first option is a board, a log, a bar. The second is built from rolled metal: a channel, a profile pipe, an I-beam, a corner. There are combined structures with the most loaded steel parts and timber elements in less critical areas.

In addition to the "iron" strength, the metal has a lot of disadvantages. These include heat engineering qualities that do not satisfy the owners of residential buildings. The need for welded joints is disappointing. Most often, industrial buildings are equipped with steel rafters, less often private cabins assembled from metal modules.

In the case of independent construction of truss structures for private houses, wood is a priority. It is not difficult to work with it, it is lighter, "warmer", more attractive in terms of environmental criteria. In addition, to make nodal connections, a welding machine and welder skills are not required.

Rafters - a fundamental element

The main "player" of the frame for the construction of the roof is the rafter, among the roofers called the rafter leg. Beds, braces, headstock, purlins, tightenings, even a Mauerlat may or may not be used depending on the architectural complexity and dimensions of the roof.

The rafters used in the construction of the frame of gable roofs, according to technical characteristics and the method of laying, are divided into:

• Fortified rafter legs, both heels of which have reliable structural support under them. The lower edge of the layered rafter rests against the Mauerlat or the ceiling crown of the frame. The support for the upper edge can be a mirror analogue of the adjacent rafters or a girder, which is a beam horizontally laid under the ridge. In the first case, the rafter system is called spacer, in the second it is non-spacer.
• Hanging rafters, the top of which rests against each other, and the bottom is based on an additional beam - a tightening. The latter connects the two lower heels of adjacent rafter legs, resulting in a triangular module called a rafter truss. The tightening dampens the stretching processes, due to which only the vertically directed load acts on the walls. The structure with hanging rafters, although it is a spacer, does not transfer the spacer itself to the walls.

In accordance with the technological specifics of rafter legs, structures constructed from them are divided into layered and hanging. For the stability of the structure, they are equipped with struts and additional struts. For the device of the supports for the top of the layered rafters, the beds and girders are mounted. In reality, the rafter structure is much more complex than the described elementary templates.

Note that the formation of a gable roof frame can generally be performed without a rafter structure. In such situations, the supposed planes of the slopes are formed by slugs - beams laid directly on the bearing gables. However, we are now specifically interested in the device of the gable roof rafter system, and it can involve both hanging or layered rafters, or a combination of both types.

The subtleties of attaching the rafter legs

The rafter system is fastened to brick, foam concrete, aerated concrete walls through the Mauerlat, which in turn is fixed with anchors. Between the Mauerlat, which is a wooden frame, and the walls made of these materials, a waterproofing layer of roofing material, waterproofing, etc. is necessarily laid.

The top of the brick walls is sometimes specially laid out so that something like a low parapet is obtained along the outer perimeter. So it is necessary that the Mauerlat placed inside the parapet and the walls do not burst the rafter legs.

The rafters of the roof frame of wooden houses rest on the upper crown or on the ceiling beams. The connection in all cases is made by cuts and duplicated with nails, bolts, metal or wooden plates.

How to do without furious calculations?

It is highly desirable that the cross-section and linear dimensions of wooden beams are determined by the project. The designer will give clear design justifications for the geometric parameters of the board or timber, taking into account the entire spectrum of loads and weather conditions. If the home foreman does not have design development at his disposal, his path lies on the construction site of a house with a similar roofing structure.

You can ignore the number of storeys of the building being erected. It is easier and more correct to find out the required dimensions from the foreman than to learn them from the owners of shaky unauthorized construction. Indeed, in the hands of the foreman, the documentation with a clear calculation of the loads on 1m² of the roof in a particular region.

The step of installing the rafters determines the type and weight of the roofing. The heavier it is, the less the distance between the rafter legs should be. For laying clay tiles, for example, the optimal distance between the rafters will be 0.6-0.7 m, and for the installation of metal tiles and profiled sheets, 1.5-2.0 m are permissible.However, even if the step required for the correct installation of the roof is exceeded, there is a way out ... This is a reinforcing counter-grid device. True, it will increase both the weight of the roof and the construction budget. Therefore, it is better to understand the step of the rafters before the construction of the rafter system.

Craftsmen calculate the pitch of the rafters according to the design features of the building, banally dividing the length of the ramp into equal distances. For insulated roofs, the step between the rafters is selected based on the width of the thermal insulation plates.

On our website you can find a calculator for calculating a gable roof, which may also help you a lot during construction.

Roof structures of layered type

The rafter structures of the layered type are much simpler in execution than their hanging counterparts. A reasonable plus of the layered scheme is to provide full ventilation, which is directly related to the long-term service.

Distinctive design features:

• Mandatory support under the ridge heel of the rafter leg. The role of a support can be played by a girder - a wooden beam resting on racks or on the inner wall of a building, or the upper end of an adjacent rafter.
• The use of Mauerlat for the construction of a truss structure on walls made of brick or artificial stone.
• The use of additional girders and racks where rafter legs, due to the large size of the roof, require additional support points.

The disadvantage of the scheme is the presence of structural elements that affect the layout of the internal space of the operated attic. If the attic is cold and it is not supposed to organize useful premises in it, then the layered structure of the rafter system for the device of a gable roof should be preferred.

Typical work sequence for the construction of a layered rafter structure:

• First of all, we measure the height of the building, the diagonals and the horizontality of the upper cut of the frame. If vertical deviations of brick and concrete walls are detected, we eliminate them with a cement-sand screed. We reduce the excess of the heights of the log house. By placing wood chips under the Mauerlat, vertical flaws can be dealt with if their size is insignificant.
• The overlap surface for laying the bed must also be leveled. He, the Mauerlat and the girder should be clearly horizontal, but the arrangement of the listed elements in the same plane is not necessary.
• We process all wooden parts of the structure before installation with fire retardants and antiseptic preparations.
• On concrete and brick walls, we lay waterproofing for the installation of the Mauerlat.
• We lay the Mauerlat timber on the walls, measure out its diagonals. If necessary, slightly move the bars and turn the corners, trying to achieve the perfect geometry. Align the frame horizontally if necessary.
• We mount the Mauerlat frame. The splicing of the beams into a single frame is carried out by means of oblique cuts, the joints are duplicated with bolts.
• We fix the position of the Mauerlat. Fastening is made either with staples to the wooden plugs laid in the wall ahead of time, or with anchor bolts.
• We mark the position of the bed. Its axis should recede from the Mauerlat bars at equal distances on each side. If the girder rests only on racks without a bed, the marking procedure is carried out only for these posts.
• We install the bed on a two-layer waterproofing. We fasten it to the base with anchor bolts, and connect it to the inner wall with wire twists or staples.
• We mark the installation points of the rafter legs.
• We cut the racks to the same size, because The bed is on the horizon. The height of the racks should take into account the dimensions of the cross-section of the purlin and the bed.
• We install racks. If provided by the project, we fasten them with spacers.
• We put the run on the racks. Check the geometry again, then install the brackets, metal plates, wooden fixing plates.
• We install a test rafter board, mark the cutting points on it. If the Mauerlat is set strictly to the horizon, there is no need to adjust the roof rafters in fact. The first board can be used as a template for making the rest.
• We mark the installation points of the rafters. For marking, folk craftsmen usually prepare a pair of rails, the length of which is equal to the gap between the rafters.
• According to the markings, we install the rafter legs and fasten them first at the bottom to the Mauerlat, then at the top to the girder to each other. Every second rafter is screwed to the Mauerlat with a wire bundle. In wooden houses, the rafters are screwed to the second crown from the top row.

If the rafter system is made flawlessly, the planks are mounted in no particular order. If there is no confidence in the ideal structure, then the extreme pairs of rafters are first installed. A control twine or fishing line is pulled between them, according to which the position of the newly installed rafters is adjusted.

The installation of the rafter structure is completed by installing the fillies, if the length of the rafter legs does not allow the formation of an overhang of the required length. By the way, for wooden buildings, the overhang should "go out" beyond the contour of the building by 50 cm. If the organization of the visor is planned, separate mini-rafters are installed under it.

Another useful video about building a gable rafter base with your own hands:

Hanging truss systems

The hanging type of rafter systems is a triangle. The two upper sides of the triangle are folded by a pair of rafters, and the tightening that connects the lower heels serves as the base. The use of a tightening allows you to neutralize the action of the thrust, therefore, only the weight of the sheathing, the roof, plus the weight of precipitation, depending on the season, acts on the walls with hanging rafter structures.

The specifics of hanging rafter systems

Characteristic features of hanging rafter structures:

• Mandatory presence of a puff, made most often from wood, less often from metal.
• Ability to refuse to use Mauerlat. The timber frame will be successfully replaced by a board laid on a two-layer waterproofing board.
• Installation of ready-made closed triangles on the walls - roof trusses.

The advantages of the hanging scheme include the space under the roof free of racks, which allows you to organize an attic without pillars and partitions. There are disadvantages. The first of them is restrictions on the steepness of the slopes: the angle of their slope can be at least 1/6 of the span of a triangular truss, steeper roofs are strongly recommended. The second disadvantage is the need for thorough calculations for the competent device of the cornice nodes.

Among other things, the corner of the truss will have to be set with pinpoint accuracy, since the axes of the connected components of the hanging rafter system must intersect at a point, the projection of which must fall on the central axis of the Mauerlat or the lining board replacing it.

Subtleties of large-span hanging systems

The brace is the longest element of the hanging truss structure. Over time, as is typical for all sawn timber, it deforms and sags under the influence of its own weight. The owners of houses with spans of 3-5 m are not too worried about this, but the owners of buildings with spans of 6 or more meters should think about installing additional parts that exclude geometric changes in tightening.

There is a very significant component to prevent sagging in the rafter system installation scheme for a large-span gable roof. This is a suspension called a headstock. Most often, it is a block attached with wooden beads to the top of a truss. The headstock should not be confused with the racks, because its lower part should not come into contact with the puff at all. And the installation of racks as supports in hanging systems is not used.

The bottom line is that the headstock seems to hang on the ridge knot, and a tightening is already attached to it with the help of bolts or nailed wooden linings. Threaded or collet type clamps are used to correct slack.

Adjustment of the tightening position can be arranged in the area of ​​the ridge assembly, and the headstock is rigidly connected to it with a cut. Instead of a bar in non-residential attics, reinforcement can be used to manufacture the described tightening element. It is recommended to arrange a headstock or a suspension also where the tightening is assembled from two bars to support the connection section.

In an improved hanging system of this type, the headstock is supplemented by strut beams. The stress forces in the resulting rhombus are extinguished spontaneously due to the competent arrangement of the vector loads acting on the system. As a result, the rafter system pleases with stability with minor and not too expensive modernization.

Hanging type for attics

In order to increase the usable space, the tightening of the truss triangles for the attic is moved closer to the ridge. A perfectly reasonable move has additional benefits: it allows puffs to be used as a basis for stitching the ceiling. It joins the rafters by cutting with a semi-rotary screw with a duplicating bolt. It is protected from sagging by installing a short headstock.

A tangible disadvantage of the hanging attic structure is the need for accurate calculations. It is too difficult to calculate it yourself, it is better to use a ready-made project.

Which design is more cost effective?

Cost is an important argument for an independent builder. Naturally, the price of a structure for both types of truss systems cannot be the same, because:

• In the construction of a layered structure for the manufacture of rafter legs, a board or a beam of a small section is used. Because layered rafters have two reliable supports under them, the requirements for their power are lower than in the hanging version.
• In the construction of a hanging structure, rafters are made of thick timber. For the manufacture of a puff, a material similar in cross-section is required. Even taking into account the abandonment of the Mauerlat, the consumption will be noticeably higher.

It will not work to save on the grade of the material. For the load-bearing elements of both systems: rafters, girders, stanchions, mauerlat, attendants, racks, 2nd grade sawn timber is needed. For crossbars and tension rods, grade 1 is required. In the manufacture of less critical wooden linings, the 3rd grade can be used. Without counting, we can say that in the construction of hanging systems, expensive material is used to a greater extent.

Hanging trusses are assembled in an open area next to the object, then transported assembled upstairs. To lift weighty triangular arches from a bar, you will need equipment, which you will have to pay for rent. And the project for complex nodes of the hanging version is also worth something.

Video instruction on the construction of the truss structure of the hanging category:

There are actually much more methods for constructing truss systems for roofs with two slopes. We have described only the basic varieties, which in reality are applicable for small country houses and buildings without architectural undertakings. However, the information provided is sufficient to cope with the construction of a simple truss structure.

Design options Roof systems

• Roof or hanging
• Spacer or non-spacer
• Mounting methods

Modern buildings sometimes amaze our imagination with the most unusual forms of roofs. They owe their stylish and effective look to the variety of truss structures. However, all of them in the skilful hands of the architect-designer are "assembled" like a constructor, connected in a certain order from standard elements.

Design options

The rafter systems of pitched roofs depend on their characteristics.

Mono-pitched- the simplest option to manufacture. The peculiarity of its design is the absence of a ridge, struts and struts. Such roofs are usually used for buildings with 6–8 m spans. Despite the simplicity of the design, with a reasonable approach, even such a simple design has its advantages. For example, on the south side facing north, fairly large windows can be installed. This is the most convenient rafter system for an extension, a garage, etc., especially since it allows you to "assemble" a roof from large-sized sheet materials.

Another simple and cheap design is considered to be a gable. However, it is not without its drawbacks. For example, in a conventional roof of this type, there is too little space for the attic.

Hip- not two, but four-slope. From a certain angle, it resembles an ordinary gable. However, its slopes do not completely cover the surface of the house - the space remaining on the sides is closed by lateral triangular hips. Thus, the roof is hipped and two types of rafters are used for its construction.

Multi-pliers- this is a structure, which, as it were, consists of a set of gable roofs with multidirectional ridges. The rafter system of such roofs is the most expensive, but it makes it possible to arrange additional space in the attic.

Tent, due to its shape, reminiscent of a pyramid, it is maximally resistant to wind load. Moreover, snow does not linger on it. And this despite the fact that her rafter system is one of the simplest. True, the absence of gables does not allow equipping even a small room in the attic.

Rafter systems

Roof or hanging

The frame for the device consists of triangular-shaped elements, due to which, even when experiencing a large number of alternating loads, the structure does not lose its rigidity. The rafter systems of pitched roofs are divided into hanging and layered.

The choice of this or that type, method of fastening is based on the following parameters:

• the size of the structure itself;
• the slope and shape of the roof;

Rafters

For buildings with a single or gable roof, the use of layered rafters is more typical. This is a structure assembled from short beams or planks with two or three points of rigid attachment. In the first version, these are the walls of the building, in the case of a gable, a ridge is added, and the ridge bar in this case must be reinforced with uprights. The beds are used as supports for the latter. The length of the rafters in buildings with large dimensions exceeds 6 m. It is quite possible that additional support structures will need to be installed here. For example, build solid walls or columnar supports inside.

Hanging

This design is characterized by the absence of intermediate supports. Such rafters often cover spans exceeding 7 m. The wall remains the only reference point for the rafter leg. As for the second end, in this case, the upper parts of the rafter bar and the opposite leg dock. For this, various methods are used: by means of a slotted spike or metal plates, a connection in half a tree.

Spacer or non-spacer

The reliability of the roof, first of all, provides a careful calculation of the loads under the influence of which its frame is located. The rafters become, as it were, "conductors" of these loads on the external supports of the structure. The load that the rafter legs put on their supports is of two types - expansion and non-expansion.

Spacer

The rafter beams in this design work in compression and bending, which causes a significant horizontal expansion force. It is naturally transferred to the walls. When installing a horizontal tightening, it will take over this thrust, and this force will decrease. This truss element has several functions:

• connects the rafters,
• serves as a support for them,
• does not allow the bases of the beams to part.

The brace can be installed at the base of the rafters, then it will act as a floor beam. It can be set higher. With such a device, the tightening is called a deadbolt. For large spans, as a rule, a complication of the structure of the trusses is required, that is, not only tightenings are installed, but other additional elements are installed.

Spreadless

The support of the lower ends of the rafter legs in this system are:

• walls, and with their upper ends they are connected to each other by a girder, which, in turn, rests on racks or
• support frames formed by upper and lower girders, struts and struts

The elements of the system function like beams, that is, exclusively for bending.

Mounting methods

Non-thrust systems. Rafters of this type are installed in such a way that one support turned out to be fixed, and the other - movable, and both of them should be able to rotate freely. In practice, there are three ways to eliminate dangerous loads acting on the walls in this case. The rafter leg is resting with its lower end against the Mauerlat. It is hemmed with a bar and fixed using a notch with a tooth. It is also advisable to insure additional wire fastening. The upper part of the beam is mounted on a ridge girder. For fasteners, the principle of sliding support is used. An example is the veranda rafter system.

• The bottom of the rafter is fixed using a movable joint. To fix the upper part after laying it on the ridge girder, use a bolt, nails, etc. This is the most common option for gable roofs.
• Rigid fastening to the purlin with nails, pins or other fasteners.

In any case, the following principle is observed: with one end, the rafter leg is fixed on a support acting according to the sliding principle, which allows rotation, with the other - on a hinge that allows only rotation.

Spacers... Both supports, in contrast to the non-thrust ones, are fixed. The installation is carried out according to the same building diagrams, only in this case, the lower supports are fixed not on the sliders, but on a hinge that allows one degree of freedom. Support bars about a meter long can be nailed to the bottom of the rafter, or the support on the Mauerlat can be attached to the "tooth".

For small light roofs, it can be arranged without a Mauerlat, but it should be borne in mind that in this case the load on the wall is distributed unevenly.

© 2018 stylekrov.ru

A gable roof or gable roof is a roof with two slopes, i.e. having 2 inclined surfaces (slopes) of a rectangular shape.

The gable roof frame, due to its design features, ideally combines simplicity of construction and maintenance with reliability and durability. These and many other parameters make the construction of a gable roof a practical and rational solution for private and commercial housing construction.

As part of this article, we will consider how to make a gable roof rafter system with your own hands. For effective perception of the material, it is presented in the form of step-by-step instructions from A to Z, from selection and calculations, to the installation of the Mauerlat and the lathing under the roof. Each stage is accompanied by tables, diagrams, drawings, pictures and photos.

The popularity of the roof of the house is due to a number of advantages:

• design variability;
• simplicity in calculations;
• natural water flow;
• the integrity of the structure reduces the likelihood of leaks;
• profitability;
• preservation of the usable area of ​​the attic or the possibility of arranging the attic;
• high maintainability;
• strength and durability.

Types of gable roof

Installation of the gable roof truss system depends primarily on its design.

There are several options for gable roofs (types, types):

1. Simple gable roof - symmetrical

Simple gable roof - symmetrical The most common version of the roof device due to its simplicity and reliability. Thanks to symmetry, an even distribution of loads on the load-bearing walls and the Mauerlat is achieved. The type and thickness of the insulation do not affect the choice of material.

The cross-section of the timber makes it possible to provide a reserve of bearing capacity. There is no chance of bending the rafters. Supports and spacers can be placed almost anywhere.

An obvious drawback is the impossibility of arranging a full-fledged attic floor. Sharp corners create blind spots that are unusable.

2. Simple asymmetrical gable roof

Simple asymmetrical gable roof Designing one angle greater than 45 ° results in less unused space. It becomes possible to make living rooms under the roof. At the same time, the requirements for the calculation are increasing, since the load on the walls and foundation will be unevenly distributed.

3. Sloped gable roof, with an external and / or internal break

Sloped gable roof, with an external and / or internal break This roof structure allows you to equip a full second floor under the roof.

Naturally, a simple gable roof rafter differs from a broken one, not only visually. The main difficulty lies in the complexity of the calculations.

The structure of the rafter system of a gable roof

Do-it-yourself roof construction of any complexity presupposes knowledge of the purpose of the main structural elements.

The locations of the elements are shown in the photo.

Elements of the rafter system of a gable roof Elements of the rafter system of a gable roof - scheme 2
Elements of the rafter system of a gable roof - scheme 3

• Mauerlat... Designed to distribute the load from the rafter system to the load-bearing walls of the building. For the arrangement of the Mauerlat, a bar of solid wood is selected. Preferably larch, pine, oak. The cross-section of the timber depends on its type - solid or glued, as well as on the supposed century of the construction. The most popular sizes are 100x100, 150x150 mm.

  Advice. For a metal rafter system, the Mauerlat must also be metal. For example, a channel or I-profile.

• Rafter leg... The main element of the system. For the manufacture of rafter legs, a durable beam or log is used. Legs connected from above form a truss.

The silhouette of the truss determines the appearance of the structure. Examples of farms in the photo.

Truss options for roof truss system

The parameters of the rafters are important. They will be discussed below.

• Tightening- connects the rafter legs and gives them rigidity.

• Run:

• Ridge run, mounted at the junction of one rafter to another. In the future, a roof ridge will be installed on it.

• Side girders, they provide the truss with additional rigidity. Their number and size depend on the load on the system.

• Rafter rack- vertically located timber. Part of the load from the weight of the roof is also taken over. In a simple gable roof, it is usually located in the center. With a significant span - in the center and on the sides. In an asymmetrical gable roof - the installation location depends on the length of the rafter. With a broken roof and the arrangement of one room in the attic, the racks are located on the sides, leaving free space for movement. If there are two rooms, the racks are located in the center and on the sides.

The position of the pillar depending on the length of the roof is shown in the figure.

The location of the rack depending on the length of the roof

• Brace... Serves as a support for the rack.

Advice. Installing the brace at an angle of 45 ° significantly reduces the risk of deformation from wind and snow loads.

In regions with significant wind and snow loads, not only longitudinal struts (located in the same plane with the rafter pair) are installed, but also diagonal ones.

• Sill... Its purpose is to serve as a support for the rack and as an attachment point for the strut.

• Lathing... Designed for movement during construction work and for fixing the roofing material. Installed perpendicular to the rafter legs.

Advice. An important purpose of the lathing is to redistribute the load from the roofing material to the rafter system.

The presence of a drawing and a diagram indicating the location of all the listed structural elements will help in the work.

Advice. Be sure to add data on the device for the passage of the ventilation shaft and chimney to the gable roof truss system diagram.

The technology of their device is determined by the type of roof.

The choice of material for rafters

When calculating the material for a gable roof, you need to choose high-quality wood without damage and wormholes. The presence of knots for beams, mauerlat and rafters is not allowed.

For boards, there should be a minimum of knots, and they should not fall out. The wood must be durable and treated with the necessary preparations that will enhance its properties.

Advice. The length of the knot should not exceed 1/3 of the thickness of the bar.

Calculation of the rafter system of a gable roof

The calculation of the parameters of the material is an important stage, therefore, we present the calculation algorithm step by step.

Calculation of the rafter system It is important to know: the entire rafter system consists of many triangles, as the most rigid element. In turn, if the slopes have a different shape, i.e. are an irregular rectangle, then you need to divide it into separate components and calculate the load and the amount of materials for each. Summarize the data after calculations.

1. Calculation of the load on the rafter system

The load on the rafters can be of three types:

• Constant loads... Their action will always be felt by the rafter system. These loads include the weight of the roof, lathing, insulation, films, additional roof elements, finishing materials for the attic floor. The weight of the roof is the sum of the weight of all its constituent elements; such a load is easier to take into account. On average, the value of the constant load on the rafters is 40-45 kg / sq.

Advice. To make a margin of safety for the rafter system, it is better to add 10% to the calculation.

For reference: The weight of some roofing materials per 1 sq. M. presented in the table

Advice. It is desirable that the weight of the roofing material per 1 sq. roof area, did not exceed 50 kg.

• Variable loads... They act in different periods and with different strengths. Such loads include: wind load and its strength, snow load, precipitation intensity.

Basically, a roof slope is like a sail and when wind load is taken into account, the entire roof structure can be destroyed.

Wind load on the roof

The calculation is carried out according to the formula: the wind load is equal to the indicator for the region, multiplied by the correction factor. These indicators are contained in the SNiP "Loads and Impacts" and are determined not only by the region, but also by the location of the house. For example, a private house surrounded by multi-storey buildings has less stress. A detached country house or summer cottage is experiencing increased wind loads.

2. Calculation of snow load on the roof

The calculation of the roof for snow load is carried out according to the formula:

The total snow load is equal to the weight of the snow multiplied by the correction factor. The coefficient takes into account wind pressure and aerodynamic influence.

The weight of snow, which falls on 1 sq. roof area (according to SNiP 2.01.07-85) is in the range of 80-320 kg / sq.

The coefficients showing the dependence on the slope of the slope are shown in the photo.

Scheme for calculating the snow load on the roof

Nuance. At an angle of inclination of the slope over 60 ° the snow load does not affect the calculation. Since the snow will quickly slide down and will not affect the strength of the timber.

• Special loads... Such loads are taken into account in places with high seismic activity, tornadoes, and stormy winds. For our latitudes, it is enough to make a margin of safety.

Nuance. The simultaneous action of many factors causes a synergistic effect. This is worth considering (see photo).

Assessment of the condition and bearing capacity of walls and foundations

It should be borne in mind that the roof has a significant weight that can harm the rest of the building.

Determination of the roof configuration:

• simple symmetrical;
• simple asymmetric;
• broken line.

The more complex the shape of the roof, the greater the number of trusses and trusses needed to create the necessary safety margin.

3. Calculation of the angle of inclination of the roof

The angle of inclination of a gable roof is determined primarily by the roofing material. After all, each of them puts forward its own requirements.

• soft roof - 5-20 °;
• metal tile, slate, corrugated board, ondulin - 20-45 °.

It should be noted that increasing the angle increases the area of ​​space under the roof, but also the amount of material. What affects the total cost of work.

Calculation of the angle of inclination of the roof

Nuance. The minimum angle of inclination of the gable roof must be at least 5 °.

5. Calculation of the step of the rafters

The pitch of the rafters of a gable roof for residential buildings can be from 60 to 100 cm. The choice depends on the roofing material and the weight of the roof structure. Then the number of rafter legs is calculated by dividing the length of the ramp by the distance between the rafter pairs plus 1. The resulting number determines the number of legs per ramp. For the second, the number needs to be multiplied by 2.

6. Calculation of the length of the roof rafters

The length of the rafters for the attic roof is calculated according to the Pythagorean theorem.

Parameter "a"(roof height) is set independently. Its value determines the possibility of arranging a dwelling under the roof, the convenience of being in the attic, and the consumption of material for the construction of the roof.

Parameter "b" equal to half the width of the building.

Parameter "c" represents the hypotenuse of the triangle.

Advice. To the resulting value, you need to add 60-70 cm. For sawing and carrying the rafter leg over the wall.

It should be noted that the maximum length of the bar is 6 lm. Therefore, if necessary, the rafter beam can be spliced ​​(building, joining, joining).

The method of splicing the rafters along the length is shown in the photo.

Methods for splicing rafters in length

The width of the roof rafters depends on the distance between the opposing load-bearing walls.

7. Calculation of the cross-section of the rafters

The cross-section of the gable roof rafters depends on several factors:

• load, we have already written about it;

• type of material used. For example, a log can withstand one load, a beam - another, a glued beam - a third;

• rafter leg length;

• the type of wood used in construction;

• distance between rafters (rafter pitch).

You can determine the cross-section of the timber for the rafters, knowing the distance between the rafters and the length of the rafters, using the data below.

Rafters section - table

Advice. The larger the step of installing the rafters, the greater the load falls on one rafter pair. This means that the cross-section of the rafters needs to be increased.

Dimensions of lumber (timber and boards) for a gable rafter system:

• thickness (section) of the Mauerlat - 10x10 or 15x15 cm;

• the thickness of the rafter leg and tightening is 10x15 or 10x20 cm. Sometimes a 5x15 or 5x20 cm bar is used;

• run and brace - 5x15 or 5x20. Depending on the width of the leg;

• rack - 10x10 or 10x15;

• bed - 5x10 or 5x15 (depending on the width of the rack);

• thickness (section) of the roof lathing - 2x10, 2.5x15 (depending on the roofing material).

Types of gable roof truss system

For the roof structure under consideration, there are 2 options: layered and hanging rafters.

Roof system types: with layered and hanging rafters

Let's consider each type in detail in order to make an informed choice.

Hanging rafters

They are used with a roof width of no more than 6 lm. Installation of hanging rafters is carried out by attaching the leg to the load-bearing wall and ridge girder. The design of the hanging rafters is special in that the rafter legs are under the influence of a bursting force. Hanging rafters with a tie between the legs reduce its influence. The tightening in the rafter system can be wooden or metal. Often the braces are placed at the bottom, then they play the role of load-bearing beams. It is important to ensure that the fastener is securely attached to the rafter leg. Because a bursting force is also transmitted to it.

Advice.
The higher the tightening is, the more strength it should have.
If the tightening is not installed, the load-bearing walls can simply "disperse" from the pressure created by the rafter system.

Rafters

They are used for arranging roofs of any size. The design of the layered rafters provides for the presence of a bed and a stand. The bed lying parallel to the Mauerlat takes on part of the load. Thus, the rafter legs are, as it were, inclined to each other and are supported by a stand. The rafter legs of the layered system work only for bending. And the ease of installation also tilts the scales in their favor. The only drawback is the presence of a rack.

Combined

Due to the fact that modern roofs are distinguished by a large variety of shapes and complexity of configurations, a combined type of rafter system is used.

Combined view of the rafter system

After choosing the type of rafter system, you can accurately calculate the amount of materials. Record the calculation results. At the same time, professionals recommend drawing up drawings for each element of the roof.

Installation of the rafter system of a gable roof

After the rafters of the gable roof have been calculated, you can proceed with the installation. We will divide the process into stages and give a description of each of them. You will get a kind of step-by-step instructions containing additional information on each stage.

1. Mounting the Mauerlat to the wall

The beam is installed along the length of the wall on which the rafters will rest.

In log cabins, the upper crown plays the role of Mauerlat. In buildings constructed of porous material (aerated concrete, foam concrete) or brick, the Mauerlat is installed along the entire length of the load-bearing wall. In other cases, it can be installed between the rafter legs.

Material prepared for the site www.moydomik.net

Splicing the Mauerlat with each other (straight bolt lock) Since the Mauerlat is longer than the standard dimensions of lumber, it has to be spliced.

The connection of the Mauerlat to each other is done as shown in the figure.

How to connect the Mauerlat?

The bars are washed down only at an angle of 90 °. The connection is made using bolts. Nails, wire, wooden pins are not used.

How to mount the Mauerlat?

The Mauerlat is installed on the top of the wall. The mounting technology provides for several ways of attaching the Mauerlat:

• strictly in the center of the bearing wall;
• offset to one side.

Advice.
Mauerlat cannot be placed closer than 5 cm to the outer edge of the wall.

To protect the timber for the Mauerlat from damage, it is laid on a layer of waterproofing material, which is most often an ordinary roofing material.

The reliability of the Mauerlat fastening is an important aspect of construction. This is because the roof slope is like a sail. That is, it is experiencing a strong wind load. Therefore, the Mauerlat must be firmly fixed to the wall.

Methods for attaching the Mauerlat to the wall and rafters

Mauerlat fastening with anchors Anchor bolts. Ideal for monolithic construction.

Mauerlat fastenings with wooden pins They are used for log cabins and beams. But, they are always used with additional fasteners.

Mauerlat fastening with staples

Mauerlat fastening to studs or fittings It is used if the cottage is built of porous materials (aerated concrete, foam concrete).

Mauerlat mounts with a sliding mountSlip mount (articulated). A bundle in this way allows you to ensure the displacement of the rafter legs when the house shrinks.

Mauerlat fastening with wire Annealed wire (knitting, steel). Used as an additional mount in most cases.

2. Manufacturing of roof trusses or pairs

Installation is carried out in two ways:

• installation of beams directly on the roof. It is not often used, since it is problematic to carry out all work, measurements, trimming at height. But it allows you to completely complete the installation yourself;

• assembly on the ground. That is, individual elements (triangles or pairs) for the rafter system can be assembled below, and then raised to the roof. The advantage of such a system is the faster execution of work at heights. And the disadvantage is that the weight of the assembled truss structure can be significant. To lift it, you need special equipment.

Advice. Before assembling the rafter legs, you need to apply the markings. It is very convenient to use templates for these purposes. The rafter pairs assembled according to the template will be exactly the same. To make a template, you need to take two boards, the length of each of which is equal to the length of one rafter, and are connected to each other.

3. Installation of rafter legs

The collected pairs go upstairs and are installed on the Mauerlat. To do this, at the bottom of the rafter legs, you need to make a wash.

Advice. Since the slots on the Mauerlat will weaken it, you can only make cuts on the rafter leg. In order for the saw to be the same and fit snugly to the base, you need to use a template. It is cut from plywood.

The ways of attaching the rafter leg are shown in the figure.

Methods for attaching the rafter leg

You need to start the installation of rafter pairs from opposite ends of the roof.

Advice. To properly position the rafter legs, it is best to use temporary struts and struts.

A string is stretched between the rafter pairs A twine is stretched between the fixed pairs. It will simplify the installation of subsequent rafter pairs. And also, it will indicate the level of the skate.

If the rafter system is mounted directly on the roof of the house, then after installing the two outer rafter legs, the ridge support is installed. Further, half of the rafter pairs are attached to it.

It is worth noting that the opinions of professionals differ on this issue. Some advise using a staggered fastening order, which will evenly distribute the increasing load on the walls and foundation more evenly. This procedure involves the installation of one rafter in a checkerboard pattern. After part of the rafter legs are installed, the missing parts of the pair are mounted. Others insist that you need to do sequential editing of each pair. Depending on the size of the structure and the configuration of the truss, the rafter legs are reinforced with struts and uprights.

Fixing with rafter brackets Additional structural elements are connected by cutting. It is preferable to fix them with construction brackets.

If necessary, you can lengthen the rafter leg.

Methods for splicing rafter legs are shown in the photo.

Methods for splicing rafter legs

Advice. The way in which the Mauerlat is lengthened (washed down at 90 °) cannot be used in this case. This will loosen the rafter.

4. Installation of the gable roof ridge

The roof ridge assembly is made by connecting the rafter legs at the top.

Roof ridge device:

• Method without using a support bar (see fig.).

Installing the roof ridge without using a support bar

• The method using a rafter bar. The beam is needed for large roofs. In the future, it can become a support for the rack.

• Timber overlay method.

Installation of the roof ridge by overlay on the timber
Installation of the roof ridge by overlay on the timber

• A more modern version of making a ridge knot can be considered the method shown in the photo.

A method for making a ridge knot

• Cutting method.

Installation of the roof ridge by cutting

After the rafter system has been installed, we make the capital fastening of all structural elements.

5. Installation of roof battens

The lathing is mounted in any case, and is designed for more convenient movement on the roof during work, as well as for fastening the roofing material.

The pitch of the lathing depends on the type of roofing material, for example:

• for metal tiles - 350 mm (the distance between the two lower boards of the sheathing should be 300 mm).
• for corrugated board and slate - 440 mm.
• we lay a continuous crate under the soft roof.

The rafter system of a gable roof with an attic - video:

Conclusion

As you can see, despite the apparent simplicity, the installation of the gable roof truss system contains many pitfalls. But, based on the recommendations given, you can easily build a reliable structure with your own hands.

Tags: Roof Gable roof Rafters