Attic roof frame nodes dimensions between the rafters. Mansard roof rafter system: diagram, design and installation features. Installation of roof rafters

Device mansard roof allows you to significantly increase useful area and rationally organize the space of a low-rise building. However, its construction often frightens home craftsmen with too complex and time-consuming process.

You should not be afraid, because the result will provide a beautiful roof and comfortable additional rooms... And in order for the result of the work to please the owner and the household, you need to know by what rules the rafter system of the attic roof is being built, in what way it is easier and better to arrange it.

At the mention of mansard roofs, we instantly recall the pentagonal gable structure impressive dimensions above a log house, concrete or brick walls. Visual memory suggests that its slopes must certainly have a different-sized bias, i.e. Bottom part the roof just has to be much steeper than the top. Due to the difference in the angles of inclination, a convex fracture is formed, which gave the roof the popular name "broken". The term reasonably migrated into the technical definitions of mansard structures. It reflects the essence of the usual standard in the device, but often has nothing to do with the configuration. Despite the fact that the construction of all mansard roofs in mandatory includes two parts, visually their presence cannot always be determined.

Purely in terms of external indicators, the prevailing number of attic structures can be divided into:

Triangular roofs, the bottom and top of which have an equal slope. Outwardly, they resemble traditional gable structures without kinks in the plane of the slopes.
Pentagonal roofs with slopes with convex corners. This category clearly demonstrates the presence of two joined parts in the structure.

In both of these varieties, the rafter system consists of two tiers stacked on top of each other. The lower structure forms a useful space of a residential attic with a height of 2 to 2.5 m, so that it is not difficult to move inside it. The second tier creates the shape of the top of the roof, it is allowed to be of arbitrary height.

By varying the angle of inclination of the upper and lower rafter legs, you can get the optimal shape of the roof in your own opinion. It is believed that the best looks is a pentagonal attic, the corners of which are in contact with an imaginary circle.

Note that the principle of building a broken roof is suitable not only for gable rafter systems. Interpreting the basic method, the attic can be organized in hip, shed, hipped and other roof structures.

Sometimes an already existing structure is remodeled under the attic, the construction of which did not use "broken" technology. However, these roofs a priori cannot be attributed to the attic category. True, no one bothers with the sufficient power of the rafter legs to use the crossbars of the pitched rafter systems as ceiling beams, and the supports of additional girders as a bar for sheathing the attic.

Found out that main feature a mansard roof is the presence of two adjacent rafter structures, connected in a triangle or pentagon of a form that is attractive to the owner. Typical are used in their construction:

An embankment, according to which the lower tier of the attic is built and used in the device of the upper part.
Hanging. In accordance with it, only the upper part of the structure is built.

If, for simplicity, the section of the attic roof is divided into two halves, you will get a trapezoid at the bottom, and a triangle at the top. The inclined sides of the trapezoid are allowed to be exclusively layered, and the sides of the triangle are layered and hanging.

Basic diagrams of rafter systems

The "classic of the genre" is rightfully considered the pentagonal scheme of the roof truss system with uprights forming the walls indoor space... Its section is conventionally divided into the simplest geometric shapes. In the center there is a rectangle, on the sides of which there are two mirrored right-angled triangles, an equilateral triangle on top.

Standard roof structure

The rafters of the lower part of the structure rest on the bottom of the Mauerlat, and the upper heel on the right or left girder. Hanging rafter arches form part of the roof frame that crowns the structure. They are supplemented with a suspension headstock in the middle if they are intended to cover a span of more than 3m. The headstock cannot be connected to the arch tightening with a cut-out, like a support post. Its job is to prevent the tightening from sagging - it is not a support, but a suspension.

Supports-racks of the layered rafters of the lower part rest on the ceiling through the bench. If necessary, to increase stability under the props, struts are mounted. Racks are connected with a bed and girders by cuts, the joints are duplicated metal corners and serrated plates. If the floor is concrete, the bed is underlain bituminous waterproofing... The bed can be laid not on the floor, but on brick posts or on leveling boards. When arranging an attic by wooden floor you can generally do without the bed and cut the racks directly into the beams.

On rather steep lower parts of the slopes of mansard roofs it practically does not work snow load, precipitation does not linger on them. However, steeply installed rafters have another problem - gusty winds will tend to turn over and tear off the roof. Therefore, the attachment of the system to the Mauerlat must be taken very seriously. In an attic situation, each rafter is tied to the walls with twists, and not through one, as with conventional pitched structures.

The method of removing the rafters beyond the wall line

It often happens that the planned attic structure forms too narrow interior space. It can be expanded by extending the rafter legs outside the walls. Those. the rafter leg will not rest on the Mauerlat, but on the beams of the upper floor. This case, in theory, does not need a Mauerlat at all. But the reinforcing struts in the scheme with the removal of the rafters are used unquestioningly, because under the extreme part of the side triangles there is no support at all.

The installation of the Mauerlat can be canceled, but the pouring of a monolithic reinforced concrete belt for attaching the beams to brick walls highly desirable. Floor beams to monolithic belt fastened with anchors, support posts are cut into them by a maximum of 1/3 of the timber thickness. An important point: the removal of the rafters behind the wall is simply obliged to form a cornice for wooden houses width of at least 0.5m, for concrete and stone at least 0.4m.

Construction technology truss structure with the extension of the rafter leg behind the wall:

We install the extreme floor beams that define the contour of the eaves. Because the floor will be loaded, the cross-section of the beams is taken from 150 × 200mm. If, when laying the starting beam, it turns out that the walls do not form an ideal rectangle, we strive to correct the flaws by changing the position of the beams.
Along the laces stretched between the fixed extreme beams, we lay and fix the remaining bars. We control the height and pitch of the beams before fastening. The distance between the floor elements is equal to the step between the rafter legs. For insulated roofs, the optimal pitch of the rafters is 0.6m, because it is equal to the width. If the rafters are mounted at a similar frequency, they can be made from a 50 × 150mm board.
We postpone the distance from the left and right edges, equal to length short leg right triangle... At the marked points, carefully using a chisel, select the nests at a third of the beam height for the extreme supports.
We will make supports by pulling out the thorns. They need to be made according to the size of the selected nests. For the manufacture of corner supports, a beam with a section of 100 × 150 mm is suitable, and two supporting supports for the gable sides of the roof should be made from it. A 50 × 100 mm beam is enough for ordinary posts. The material for the supporting elements should be longer than the design height by the length of the tenon, but better by 10 cm in case of errors during stitching.
We install corner posts and fasten them with temporary spacers. We connect the racks with a cord.
Along the lace with a plumb line, we verify in the beams the sampling points of the nests for ordinary supports and select the indicated holes.
We install ordinary racks and two bearing supports in the centers of the attic gables.
We put girders on the installed supports - boards with a section of 50 × 150mm. We fix the girders with corners. It is not necessary to use the same number of nails as in the corners of the holes. Enough two or three for each plane. As a result of laying the boards, a frame of the walls of the future attic is obtained.
We connect the supports installed opposite each other with bars, attaching them to the girders with corners. These elements will function as tension transoms. Therefore, for their manufacture, you will need lumber of the 1st grade with a section of 100 × 150mm. A temporary support of 25x150mm inch is required for each installed transom.
From above, we temporarily fasten the crossbars with the same inch, stepping back from the edges of the frame 20-30 cm. A temporary rare flooring of one, two or three boards is needed for the convenience of installing the upper part of the rafter system.
We make a template for the rafters of the lower row from the inch. To do this, we apply a blank board to the end of the purlin and the beam. Then we outline the lines of the grooves along which the excess is to be sawed off. We try on, if necessary, we add the surplus.
We make rafter legs according to the template. If there are doubts about the impeccability of the construction, then it is better to cut out only the upper groove for a start. By placing the rafter in its proper place, it will then be possible to correct the lower groove in fact without unwanted damage to the material.
We install the end rafter legs, which will need to be connected again with a lace.
Focusing on the lace, we mount the rafter legs of the lower tier of the attic.
Similarly, we make a template for the upper part of the rafter system. In order to find the line of the upper cut, we temporarily sew a board on the pediment support.
We make a mirror brother for the previous template. The rafters of the upper tier will lean against each other.
Trying on both patterns on the roof. If everything is normal, we use them to make the required number of upper rafters from a board of 50 × 150mm.
We build the upper tier of the rafter system.
In order to prevent the crossbars from sagging, we mount the headstock of the required size to each upper truss. Sew them rigidly only to the ridge area, the bottom should not be rigidly fixed.

Further, the rafter legs are screwed to the walls with wire bundles. Then the frame of the pediment is installed, along which it needs to be sheathed. At the end, the crate is mounted with a step corresponding to the characteristics roofing material.

Wireframe method

The technology differs from the previous method in that not separate supports are installed on the floor, but modules-blocks of the side walls of the future attic completely prepared for fastening.

The block method of constructing the rafter system allows you to optimize the construction of the attic roof, because the construction of modular elements is carried out on the ground. In calm conditions, without a sense of height, it is easier to achieve accurate nodal connections.

The process of installing a modular attic roof:

According to a pre-made project, we make the frames of the attic walls. Longitudinal beams according to this method play the role of girders and beds. We lay them out together with the racks on a flat area and mark with the help of a square the nests for the supports of the side walls. We make cuts along the measured lines.
We cut out spikes on the racks, the size of which must correspond to the size of the nests.
We connect the longitudinal beam with vertical posts, we get two modular frames - these are the walls of the attic.
We raise the frames upward, set them in the intended place. We temporarily fix the position of the walls with spacers, then attach them to the floor beams with brackets.
With a chisel we select nests at the edges of the beams for installing the lower row of rafters. They must be placed in one line. To observe the geometry, it is easier to first outline them with a chainsaw, then modify them with a chisel.
We perform the upper rafter tier of the attic on the ground, having previously tried on the blanks for the installed elements. For an accurate fit to the end of the future roof, we temporarily nail the board so that one of its edges clearly repeats the central axis of the rafter system. The base of the upper mansard triangle serves as a stretch. Its length is equal to the distance between the outer vertical planes of the installed frames. We select the nests at the edges of the stretch, and spikes on the lower heels of the rafters.
We collect roof trusses of the upper tier, for reliability we mount an additional crossbar, reinforce the ridge knot with a triangular lath of wood.
Until we moved to the roof, we make blanks of rafter legs. We try them on to the frames laid out on the ground. It is more convenient to "cut" them in one fell swoop, grabbing several pieces with a clamp. We cut out only the upper bevel, taking into account that it will rest partially on the wall rack, partially on the stretching of the upper rafter trusses.
We try on the lower rafter to the end. We draw in the area of its lower heel the shape of a thorn, repeating the configuration of the nest in the beam. We cut out the thorns.
We move the trusses of the upper tier and the rafter legs of the lower tier to the roof. We mount the trusses first, attaching them to top harness walls with brackets, then the rafters of the lower part, attaching them to the floor beams with the same brackets.

The subsequent stages of roof construction are carried out according to standard rules. They will acquaint in detail with the described principles of constructing a rafter system, drawings for the attic roof, which clearly represent the structure. Due to the production of joints with a half-wood cut, the strength and rigidity of the frame as a whole increases, which will allow not to mount additional struts.

The disadvantage of this method is that ready-made modules rather difficult to transport to the roof. To transfer the assembled blocks there without the use of lifting equipment, at least 4 people are required.

Board-nail rafter system

It is impractical to build a powerful attic over small country houses, but you still want to save space on a small-sized plot. For the owners of small buildings, there is an excellent option - a light plank-nail layered structure. Those who like to save money should like the method, because a solid timber is not used in the construction.

For the manufacture of each of the supporting elements, two boards are used, between which distance pieces of the bar are installed. The cavity formed by the bars explains why the system is light compared to its solid counterparts. To ensure spatial rigidity, wind contractions are installed, connecting the supports with the rafter legs. In turn, the lathing will contribute to the strengthening of the structure.

The popular way of developing a layout

A project is highly desirable for a successful work result. It is not a fact that the presented drawings with dimensions are suitable for arranging a particular house. Typology in construction is now not at all welcome. If there is no documentation at all, it is better to make at least a sketch of the future roof, not forgetting about the height of the ceilings in the attic. Wherein:

Proportions should be observed, because too large an attic can turn small house into an awkward, mushroom-like building.
It must be remembered that the lower part of the attic roof is built using layered rafter legs, and they optically lower the overhang and overlap the upper part of high-placed windows. There will be no perceptible overhang effect when the attic is arranged according to the scheme with the removal of rafters.
Do not forget that the height of the attic room must ensure freedom of movement. It is this landmark that is required for correct definition the height of the mansard wall racks.

You can choose the best proportions of the roof using the folk template-layout method. According to him, on a flat, spacious area, bars or boards are laid out, repeating the contour of the structure in real size. By changing the angles, moving the components, you can achieve the optimal configuration. The elements must be fixed with nails and immediately measured the lengths of beams, rafters, puffs, racks. The dimensions obtained will help in the manufacture of templates.

The calculations and layout of the rafter system under the attic roof will be demonstrated by the video:

The basic options and diagrams of the attic rafter structure given by us will help you make the right choice optimal type rafter structure.

The living space located in the attic is called the attic. The advantage of the attic is obvious - it is the ability to increase the usable space of the house, while not spending too much money. In this case, the rafter system of the attic roof must meet the standards of strength and reliability. It depends on these indicators how well the main protective functions of the roofing system will perform.
The most profitable is such a mansard roof, each angle of the slope of which is different from the rest. This allows for more profitable use of the attic space.

Rafters for the attic are of two types: layered and hanging.

Reinforced rafters are used on those buildings where there is an intermediate load-bearing wall. Thus, on one side, the rafters rest on outer wall buildings, and on the other on specially created supports or an internal wall.

Please note that a layered rafter system is possible only if the distance from one load-bearing wall to another does not exceed 7 meters.

Hanging rafters are used when the building does not have internal solid walls. Most simple types Hanging trusses consist of rafters and a lower belt, that is, puffs. The Mauerlat serves as a support. Depending on the expected loads, the rafter system is additionally reinforced with brackets, wire mounted in the walls. For the construction of the frame, boards are used, the length of which depends on the length of the span between the trusses.

The mansard type of roof is more often used in the construction of private residential buildings. There are several reasons for this:

This type of construction is not difficult for installation, the roof truss system does not cause difficulties even for novice builders. This does not require large financial investments... The result is a comfortable living space and a roof. Practically - one more floor in the house.

It will not be difficult to organize an attic room in an already finished house, while the changes will not affect the supporting structures of the house. To remake old roof to the attic. It is only necessary to demolish the old roof and build a new one in its place.

However, pay attention to the building foundation, soil and bearing structures, since the mansard roof is heavier and more massive. So, if possible, it is advisable to take into account the construction of a mansard roof even at the planning stage. Thus, it will be more convenient to calculate the roof truss system.

The construction of the roof truss system

There are several types of attic roof:

symmetrical;
broken line;
asymmetrical;
triangular.

It should also be noted that it is possible to install single-level and multi-level attics with rooms of different geometric shapes. This cannot but affect the appearance of the house.

Equally important when erecting a mansard roof is the angle of the roof slopes. It depends on the following factors:

from the climate of the area;
from the material used;
from the architectural preferences of the owner.

However, we draw your attention to the fact that if you take a too large angle of inclination of the roof, this will reduce the amount of usable attic area. Too much small angle slope will lead to difficulty in the operation of the roof itself: cleaning from precipitation, strength.

The roof structure of a mansard roof consists of the following elements:

rafters;
skate;
racks;
struts;
lathing;
mauerlat;
roof;
connecting elements.

Mansard roof construction

Installation of rafters - photo

Installation of the roof truss system is carried out in stages. Since it is a rather complex and important process, on which the longevity of the entire attic structure depends.

When erecting a rafter system, you must know and follow the following rules:

Installation and calculation of the roof truss system

Construction of the attic roof of a country house

In a small country house attic - the rafter system is being built according to the same rules listed above. The main task will still be the correct calculation of the load to which the roof will be subjected. Why is it so important in construction country house? Often, in winter period suburban areas remain empty. Thus, the roof of the house can be very big amount snow cover, which creates a significant load on all elements of the house, including the rafters for the attic.

If it is decided to independently engage in the construction of the roof, then the following installation procedure must be observed:

racks are cut into the floor beams;
rafter legs are installed for the lower slopes;
the upper beam is attached to the attic floors;
a ridge rack is cut into the attic floor beam, for the upper slope;
further rafter legs are installed for the upper slopes;
at the intersection of rafter legs and floor beams, additional fasteners are installed.

Rafter system a mansard roof must have several layers. You need to take care of the processing building material, about thermal insulation and waterproofing. Choose a durable, dried material, free of knots and cracks, check the integrity. disadvantages wooden products significantly affect the strength of the rafter structure.

More and more architectural, original houses decorated with bay windows, superstructures, mezzanines. Attics are becoming fashionable, expanding the usable area of the house. But mansard roofs, as opposed to simple gable roof, require complex truss systems. It is not at all easy to calculate them correctly and carry out installation. Below we will try to briefly highlight this issue and give helpful advice specialists.

At the design stage, the house must be calculated roof structure... Calculations using complex formulas should give the value of the load per meter of a square rafter system. For residential buildings regulatory load is 50 kg / m2.

In accordance with the calculations, the type of attic roof structure is selected. The main varieties include:

hanging rafter system;
sloping roof rafter system;
layered gable roof system;
combined.

The most common are combined rafter systems. pitched roofs... It is recommended to entrust the calculation of complex rafter systems to professional designers.

Advice!
To increase the usable area of the building, you should choose a multi-slope mansard roof design.

Truss roof elements

Experienced specialists will perfectly understand what in question in the article, because they know all the terms and names of structures. In order to make it clear to everyone, here are the common names of the elements:

Mauerlat - a beam mounted along the upper rim or along the wall of the house, on which the rafter system rests;
Floor beams - wooden structure, playing the role of the attic floor and, at the same time, the ceiling of the lower room;
Racks are vertically mounted pillars on which rafters and beams are attached.
Girders - beams (boards) located horizontally, serve as a support for the rafters;
Rigel - horizontal beams in a U-shaped truss. They serve as a support and tighten pitched rafters, have another name "tightening";
Rafters - timber or boards that form the basis of the roof structure;
Suspension - a rack, the task of which is to support the crossbar, making it easier to work, is also installed horizontally;
Sheathing - a board or plywood base on which the roofing material is laid;
A filly - a board that serves as the basis for the installation of the overhang, is installed at the bottom of the rafter system.

Rafter system calculations

The choice of a rafter structure largely depends on the size of the building, in accordance with which the length of the span is determined, i.e. the distance between the main posts. For small houses, preference can be given to a gable structure.

Structural calculations are carried out in order to determine the load, in accordance with the standards and building regulations... The basic rule for a mansard roof is to limit its height, which should not be less than 2.5 meters indoors. Thus, the roof must be at least 2.80 m in height, since the installation of an insulating layer is required, and finishing inside the attic itself.

It is imperative to make a design drawing, on which all dimensions should be affixed and the elements of the frame should be displayed as much as possible. The drawing should show the dimensions of the house, the angle of inclination of the rafters, and the height of the roof.

Advice!
To spend accurate calculations for all loads on the roof and its elements, it is recommended to use the calculator posted on many sites dedicated to the construction of roofs.

It is enough to make the form roofing, material of the mansard roof frame and dimensions. The program will calculate the angles of the section and the pitch of the rafters, give recommendations for the construction of the lathing.

Calculation of the rafter system

Mansard roof installation technology

You should start with the installation of the Mauerlat, which fits around the perimeter top edge walls, if the house is brick or block. In houses made of timber or chopped with Mauerlat, the upper crown can serve. The beam from which the Mauerlat is made must have a cross-sectional size of 100x100 mm or 150x150. Wood conifers for the timber must be well dried. The Mauerlat beams are fixed with anchors or studs to the walls in increments of about two meters. Waterproofing, usually of a roll type (roofing material), is brought under the Mauerlat.

Next, you should proceed with the installation of the floor. Beams 150x200 mm, laid on the Mauerlat, should protrude from the walls of the house by about 0.3-0.5 m. The beams are fastened with corners and screws (wood screws), starting with the extreme ones, then intermediate ones.

Important!
When laying, use a cord to control horizontal level so that the beams lie in the same plane.

The distance between them, as a rule, is 0.5-1.0 meters, if it is planned to lay insulation, the standard sheet width of which is 0.6 m, then it will be more convenient to maintain the same pitch of the beams.

Installation of roof truss system

Installation of support posts and purlins

The next stage is the installation of the racks. For them, a beam of 100x150 mm is used, which is fastened to the front floor beams. It is necessary, using a plumb line, to align the verticality of each support and fix it with jibs. Intermediate supports are also installed on the beams strictly vertically, forming two parallel rows.

This is followed by the installation of girders, which can be made from a board 100-150 mm wide and 40-50 mm thick. The girders are fixed with nails and corners on the screws. Then, on top of the purlins, plank girders are laid, for rigidity, installed on the end.

Advice!

As a result, the contour of the future attic room is formed. To give additional strength, the supports should be strengthened with struts and fights.

Installation of rafter elements

Installation of rafters starts from the bottom. For them, a board 40-50 mm thick and 150 mm wide is suitable. With one end we rest on the Mauerlat close to the floor beams, and the other is attached to the girders with the help of corners, screws and nails. To install the rafters at the top of the roof, mark the center line of the roof. All rafters must be of the same length. To do this, make a template board by making cuts on it from both ends. After that, the rest of the rafters can be sawed off according to the template.

The rafters are mounted on girders, fixing in the upper part with metal plates. On the girders, the beams are fixed with saws at an emphasis and are fixed with corners on self-tapping screws.

For strength, the lower rafters should be reinforced with struts (board 50 × 150 mm). After fixing the struts, the temporary stops can be removed.

Installation of rafters

Lathing

In cases where the floor beams are laid in wall pockets, fillets should be fixed on the lower rafters for the roof overhang. If the floors are on the Mauerlat, then the filly is not needed, since the beams should protrude beyond the walls to form an overhang.

The lathing is installed depending on the intended covering of the attic roof. Either the lathing will be solid or with gaps. A waterproofing layer should be laid on top of the sheathing, after which you can start sewing the gables and laying the roofing material - metal, corrugated board or slate.

Roof lathing under metal roofing

Attic insulation

If the roof of the attic has a broken structure, then, as a rule, it is not insulated, since the air gap under the rafters protects the premises, while simultaneously ventilating the under-roof space. To do this, sewing up the gables, you should leave ventilation windows (holes) above the attic floor. Thermal insulation should be done only inside the attic room.

The attic insulation device has its own characteristics, since the rooms have triangular or trapezoidal ceilings. Builders consider insulation as one of the most difficult technological tasks in the device. attic rooms... The main thing is to lay the thermal insulation so that on sloped ceiling and on fences, it did not shrink during operation.

Attic insulation

As experienced builders say, an attic can be arranged in a house, there would be a roof. The type of roof affects how much this measure will increase the usable area, whether it is comfortable to use this room and what kind of work will be required. Common types of roofs for arranging a residential under-roof space are gabled I, straight and broken slopes.

The roof rafter system is designed to free up space in the center where the ceiling heights reach an acceptable height by placing the bulk of the supporting elements at the edges. This article will tell you what the roof frame consists of, how to choose the best design option and correctly perform the installation.

Types of truss systems

When starting to design a rafter system for a mansard roof, pay attention to the layout of the house. Based on the types of supports, choose suitable option devices:

Naslonnaya. This type of truss frame is suitable for houses in which there is a load-bearing partition in the middle. Then the weight of the roof structure is distributed between it and outside walls structures. It is unobtrusive and rational way organization of the frame, but it is suitable if the distance between the outer walls and the inner support does not exceed 7 m.
Hanging. This type is used when there are no load-bearing partitions or columns inside, which are used to transfer the weight of the roof onto them. The hanging rafters are supported by the Mauerlat and ridge girder... For roofs up to 50 sq. m, with a low roof weight, the simplest configuration is used, consisting of rafter legs and a horizontally located tightening. To block the structure large size, this structure is strengthened with stands, contractions, struts. These elements increase the stability of the roof, but "eat up" the usable area of the attic. Allowable distance between the walls of the structure for hanging rafters is 14 m.
Combined. The mixed type of rafter system is used when support columns are installed in the middle of the house instead of the load-bearing partition. It turns out that part of the rafters can be leaned against the columns, and the rest can be mounted as hanging ones. This method is quite often used for arranging mansard roofs, since it allows you to use less auxiliary elements, reducing the load on the foundation and not cluttering the under-roof space.

Please note that the device of the attic must be planned at the stage of creating the project, because the type, weight and design of the rafter system are necessary for calculating the foundation. If the decision to erect a mansard roof arose at the final stage of construction, it is necessary to recalculate the mass of the house taking into account the new data in order to check whether the foundation can withstand the additional load, especially if the site has complex soil and a small distance between the surface and groundwater.

Calculation of the elements of the rafter system

By building codes a room is called residential if the height from the floor to the ridge is at least 2.5 m and there are sources of natural light, that is, windows. Therefore, the main parameter of the attic roof, which must be calculated, is the angle of inclination of its slopes. The catch is that if you lay a small slope, then the height of the ceilings in the attic will be lower than what is allowed by the rules. And if you make covered slopes, the roof will turn out to be very heavy, expensive and unstable. Therefore, it is used, the slopes of which change the slope, its upper rafters have an acute angle of 30 degrees, and the lower ones - 60 degrees.

Tilt angle and ceiling height

An important stage in the design of the attic roof is the calculation of the size of the cross-section of the elements of the rafter system. The easiest way is to find out the recommended size in the look-up tables with calculated values that take into account the length, distance between adjacent elements, type and quality of the material. However, if the roof custom size it is necessary to perform a calculation based on calculating the total load from the weight of the roof, which falls on the rafter system. The calculation scheme also takes into account temporary loads in the form of a mass of snowfall, which are reflected in the climatic coefficient, which characterizes the nature of the weather at the construction site.

To create the rafter system of the attic roof, wood is used, but not in all cases it is advisable, since in order for the rafters to cope with the load, it is necessary to increase the cross-section of the lumber used, which further increases the weight of the structure. To break out of this closed cycle, it is necessary to abandon wood in favor of higher strength metal rafters.

The structure of the rafter system

The constituent parts of the rafter frame of the attic roof are no different from the design of other types of pitched roofs. It includes:

In most cases, the elements of the rafter system are made of wood. High Quality... To avoid deformation during operation, it must be dried to a moisture content of 15-18%, processed antiseptic impregnation deep penetration and fire retardant if you plan to bring the chimney to the roof.

Assembly sequence

It is better to assemble the rafter system using experienced master, since even lifting heavy, long bars is problematic. It is not recommended to install in rain and snow, as the moisture content of the wood will increase during operation. Usually the build process looks like this:

Reliability of the rafter system mansard roof depends, first of all, on the correctness of the calculations, therefore, if you are not confident in your engineering abilities, it is better to use typical project created by a professional architect.

Video instruction

I continue the story about how I build my house, and today I will talk about the roof system of the house. I had thoughts about what system to do, and after weighing all the pros and cons, I settled on one option, which one? Read on - I'll tell you everything!

In this article I will talk about how I drew up the project of the rafter system, how I calculated the step of the rafters, how the rafters of the attic roof were installed, and I will also tell you how the rafters of my house are attached.

A small outline of the article:

The choice of the rafter system
Calculation of the step of the rafters
Cooking rafter blanks
Brief conclusion on the article
Home News

Now in more detail each item.

The choice of the rafter system

When I was planning the house, there was a lot of variation on the type of roof of the house. The fact that the roof will be an attic was not even discussed, but what shape?

I originally wanted to do sloping roof- a la the 90s, but when I began to calculate the floor beams of the house, I realized my mistake, and began to look for another option. In this version, I got a large deflection of the ceiling beams in the ceiling of the first floor. This was not permissible - I had to think further.

Part of the first version of my house

As a result, I settled on a gable roof attic, with a wall height of 120 cm near the Mauerlat. This height turned out to be quite convenient for my roof angle. I can freely reach the wall of the house with my hand without bending over, though with my forehead against the ceiling)))

The appearance turned out to be very attractive. Installation of the roof of such a roof was also convenient, you can walk freely on the roof. There was a small problem with the material, but I waited a little, and they sawed me necessary board.

Calculation of the step of the rafters

I chose the step and section of the rafters based on calculations, the principle is the same, only not the entire length of the rafter is taken into account, but only its horizontal projection.

In general, of course, there are specialized formulas that take into account the average snow load, depending on the region. In a separate article, I plan to tell you how to calculate the rafter system for any region. I practically neglected this, just taking the load as for overlapping the house.

The distance between the roof rafters is 60 centimeters, the thickness of the rafters gable roof or, more correctly, the section turned out to be 180x50 mm. This is quite enough in our area, there is practically no snow, here is a photo, you can see the date yourself))) This moment, of course, infuriates me in our climate, but what can I do ...

Pay attention to snow on roadsides and on rooftops

Of course, sometimes it dumps 60-70 centimeters over the winter, but this happens once a year 10-15 probably. Only the winds blow almost incessantly here, and they sweep everything from the rooftops. Of such beautiful roofs as in the photo below in Transbaikalia, you practically will not find ...

Beauty !!!

Cooking rafter blanks

After all the calculations were done, then I just picked up optimal angle the roofs, taking as a basis, is that I cannot get boards longer than 6 meters (6 meters, then only one sawmill in the village saws, and then only five and a bar), overhangs at least 60 centimeters from the wall, appearance should be attractive.

Right in the visio I put two boards right on the facade project, choosing the most optimal angle. When I finished with an angle, I measured the distance from the ridge to the Mauerlat (the project was originally done to scale, so as not to butt with dimensions later) I drew a drawing in a compass, printed it out, and made rafters for the roof according to the drawing.

Mauerlat part drawing

Full rafter drawing

Skate drawing

An important fact will be to make the correct cut of the rafters. You can see how to file a building on my drawing and in this video, Larry told how to do it different ways.

Videos in preparation

I have ridge roof with layered rafters, all the rafters rest on the ridge and therefore it was made quite powerful.

The ridge was knocked together from a hardwood board with a section of 22x50 centimeters and the final section turned out to be 22x10 cm, with a ridge length of 9.6 meters. A very powerful and heavy thing, which we, like six of us, stuffed into its place.

Here the skate rests on a support

Places prepared for the ridge in the gables of the house, and an additional two support pillars, as a result, the skate rests on the ground at four points.

This ridge sits in its place in the pediment

Lifting and assembling the rafter system

When the rafters were prepared and the ridge of the house was installed, my brother and I began to install the rafters of the attic roof. The rafters were made of pine, so they could be lifted by one person on the ground and taken by another on the second floor of the house.

All the rafters were neatly folded over the Mauerlat outside the house, then I climbed onto the load-bearing central wall of the house, took the rafters, and my brother handed them to me. Of course, you can assemble the rafter system alone, but you run and jump, it is better to immediately call an assistant.

Attached at the same time, I to the ridge, brother to the Mauerlat. In general, correctly calculated and sawn-off rafters do not go anywhere when you put them in their place. They just sit and wait for you to beat them.

Here you can clearly see how the rafters are hammered together.

And yes, I forgot to say, the markings were previously made according to the calculated distance between the rafters - on the ridge and on the Mauerlats of the house, so that the entire roof turns out to be flat and all the rafters are in place.

Fastening the rafters in frame house does not cause any difficulties. The main thing is not to violate the principle of operation of the nodes frame house and everything will work out.

The rafters are fastened to the ridge with nails obliquely on both sides, then they are hammered together, forming a kind of lock, which cannot be pulled apart with all the desire.
The rafters outside the ridge were deliberately prepared a little longer, then the excess was simply sawed off with a saw. But it turned out to be a good supply for nailing.

Since the roof is ridge, I did not have a question about how to attach the rafters to the Mauerlat. I simply fastened them with 120 nails obliquely on both sides. I think nothing should run anywhere.

Fastening the rafters to the Mauerlat

The outriggers of the facades are made of the same rafters, only they are sawn off so that they butt close to each other, as they are located in the same plane. They rely on a pre-released skate and Mauerlat beams. It was a complete improvisation, and time will tell how it will behave. I hope nothing runs away and falls. Still, not only two points are held, but also the crate.

Overhangs of the house, soffits not yet completed

After installing all the rafters, I set about installing the puffs. The puffs I have come with the same pitch as the rafters, and are made of a 150x50 cm board.
In the center, the puff is nailed to load-bearing wall, and relies on it. The ends of the puffs are hung out according to the level, and the rough ceiling of the attic was subsequently screwed onto them. The roof was fastened very firmly, especially after the installation of the battens and the ceiling.

I walked freely on the ceiling from above when I dragged bags of sawdust, and he keeps the weight of the sawdust quite calmly.

Draft ceiling, it is now windshield, and on it 25 centimeters of sawdust

Let's make a short conclusion:

The whole process of assembling the rafter system can be divided into several separate stages work.

We find out the distance from the ridge to the Mauerlat at home - for correct calculations.
We calculate the step of the rafters, and their cross section. We select based on the capabilities and availability of materials for sale.
We select the optimal angle of the rafter system. I relied on the attractiveness of the house.
We calculate the location of the cuts and their angles, or as I did - we draw the rafters in " full height».
We make rafters, we leave a stock at each end. Saw off from above after piercing, from below along the thread - also after installing all the rafters.
We lay out the rafters on the Mauerlat, in their approximate location.
We raise the rafters to their place. We use an assistant, it will be hard for one.
We pierce the rafters in the field. With five nails I pounded the rafters together, two each to the ridge and three nails to the Mauerlat.

Home News

From home news, especially nothing unusual happened, I closed the next session, studied all January, the next one in May. I closed it pretty well, I attached the screen)))

Student type

Lera decided to make a huge dragon with a wingspan of about a meter, which we will see together! So far, only the frame is ready.

I think it's time to finish the article on this note, I think installing the rafters of the attic roof will no longer be something supernatural for you, even if you don't do it yourself, then you can definitely control it.

If you have any questions or suggestions, or constructive criticism, then welcome to the comments. Don't forget to subscribe to updates.