Mansard roof installation procedure. The device of the roof truss system. The structure of the rafter system

The device of the attic roof allows you to significantly increase the usable area and rationally organize the space of a low-rise building. However, its construction often frightens home craftsmen with too complicated 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 a pentagonal gable structure of 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. the bottom of 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 has 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 design of all mansard roofs necessarily includes two parts, their presence cannot always be visually 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 that have 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 a pentagonal attic looks best, the corners of which are in contact with an imaginary circle.

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

They found out that the main feature of a mansard roof is the presence of two adjacent rafter structures connected in a triangle or pentagon of a shape 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, a trapezoid will be obtained 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, which form the walls of the interior. Its section is conventionally divided into the simplest geometric shapes. In the center 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. With the bed and the girders, the racks are connected by cuts, the joints are duplicated by metal corners and toothed plates. If the ceiling is concrete, bituminous waterproofing is underlain under the bed. The bed can be laid not on the floor, but on brick posts or on leveling boards. When arranging an attic on a wooden floor, you can do without a bed at all and cut the racks directly into the beams.

The snow load practically does not affect the rather steep lower parts of the slopes of the mansard roofs, because 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, like with conventional pitched structures.

The method of removing the rafters behind the wall line

It is not uncommon for the planned attic structure to form too narrow an 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 reinforcing struts in the scheme with the removal of 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 abolished, but the pouring of a monolithic reinforced concrete belt for attaching beams to brick walls is highly desirable. The floor beams are fastened to the monolithic belt with anchors, support posts are cut into them by a maximum of 1/3 of the beam thickness. An important point: the removal of the rafters behind the wall simply must form a cornice for wooden houses with a width of at least 0.5 m, for concrete and stone at least 0.4 m.

Technology for the construction of a rafter 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 with a similar frequency, they can be made from a 50 × 150mm board.
From the left and right edges we set aside a distance equal to the length of the short leg of a 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 cutting out the spikes. 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, we calibrate with a plumb line 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 ties. Then the frame of the pediment is installed, along which it needs to be sheathed. At the end, the lathing is mounted with a step corresponding to the characteristics of the 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 a rafter system allows you to optimize the construction of a mansard 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:

We make the frames of the attic walls according to a pre-made project. 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 carry out 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 along the edges of the stretch, and spikes on the lower heels of the rafters.
We assemble the 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 stretch 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 first mount the trusses, attaching them to the upper strapping of the 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 the construction of the rafter system, the drawings for the attic roof, which clearly represent the structure. Due to the production of joints by 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 the method is that the finished modules are 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 a 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 to correctly determine 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 outline of the structure in real size. By changing the angles, moving the components, you can achieve the optimal configuration. The elements need to be fixed with nails and immediately measure the lengths of beams, rafters, puffs, racks. The resulting dimensions 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 determine the choice of the optimal type of rafter structure.

Project documentation

We are completing the attic for an already finished house
What is included in the rafter system?
Heat engineering
Construction process in detail
Benefits of the frame system

Many private home owners want to make their home more functional. You can achieve your goal by increasing the free space, which can be used for personal purposes. Experts suggest using the area under the roof itself for this, namely, to build an attic. This process cannot be called easy, but subject to technology compliance, you can make a superstructure, both at the stage of building a house, and after putting it into operation. Both options will be considered below.

We develop a project

Mansard roof - design and calculation

Anyone who is interested in how to build a mansard roof with their own hands, first of all, need to understand that this part of the building is quite complicated. If there is such an opportunity, it is better to design an additional floor during the construction phase, because not all already erected houses can be equipped with additional square meters. The main obstacle is the increase in the load on the foundation, which requires its strengthening.

In general terms, the whole process can be divided into stages:

construction of a mansard roof begins with drawing up drawings;
then the walls of the roofing room are erected;
the next stage is the arrangement of the roof itself, the performance of work on insulation, waterproofing;
installation of windows;
interior decoration of the room.

Only strict adherence to technology makes it possible to obtain a durable, and most importantly, reliable building as a result.

Each stage of work is important in its own way, one of them is design. Here it is important to take into account the dimensions of the room, the material that will be used as the main one, the features of the roof, the degree of its slope, the number of slopes, etc. There are several ways to design an add-in.

The least expensive is the compilation of the necessary documentation by hand, for this you will need at least minimal experience and knowledge. You can go the other way - use ready-made drawings, but no one can guarantee that they will be perfect, you may need to make adjustments.

The most expensive but sure-fire option is to contact a specialist. There are many companies offering to draw up a project in a short time that matches the parameters of your home. The team of specialists will also help you to choose the right building materials. The main requirements for consumables are: ensuring durability in operation, reducing the total load on the base. We must not forget that a new project must be approved by state institutions, if it is drawn up correctly, then there will be no problems with this.

What if the house has already been built?

In this case, the construction process begins with dismantling work. Having disassembled the old roof, you can not only expand the usable space later, but also ensure the safety of the new superstructure. You do not need to hire someone for these purposes, everything can be done on your own. First, remove the roofing material from the outside, then the sheathing, and at the end you disassemble the rafter system.

When the dismantling work is successfully completed, proceed to strengthening the walls on the lower floor. The stage cannot be neglected, because the additional load is not only on the foundation, but also on the vertical structures. To do everything right, you will need to carry out calculations in order to determine the level of strength of the old walls.

Mansard roof - structural components

To understand how to build a mansard-type roof, information about the main bearing parts and connections will help.

Rafter legs - they transfer the load exerted by the weight of the roofing material on the walls of the building. The section of wooden beams is selected taking into account such indicators as the angle of inclination, span width, step, design load. If you do not know how such calculations are carried out correctly, it makes sense to contact a specialist. In private construction, the use of approximate values is allowed, but we must not forget about a small stock.
Narodniks - this is the name of the rafter legs, supported on one or both sides by the nipple elements. Their cross-section is determined in the same way as in the case of the main rafters.
Slant legs - this type of construction is used in the construction of a hip roof. It is used as a base for wives. The section indicator is determined taking into account the load, the span. Remember, this figure should be more than that of the rafter legs.
The crossbar is a support bar for rafters, located in the upper part of the structure, namely in the ridge or at the break of the slope (if a sloping roof is planned).
Mauerlat is one of the main elements, it is a support for all rafters, the load on the walls is transmitted and evenly distributed through it. The optimal section is 100x100 or 150x150mm, it all depends on the complexity of the object.

So that you know, the construction of a Mauerlat is not required when it comes to the construction of a frame or wooden house. This is because the support for the rafters is the crown of the walls or the strapping.

In construction, it does not do without additional elements, such as struts, struts, contractions. They are necessary to reduce the cross-section of the supporting structures. Their size is selected taking into account the convenience of making connections. Reasoning on the topic: "How to build a mansard roof of a house", — it is impossible not to mention the material. Experts emphasize that only coniferous species, such as pine, larch, spruce, should be used. The grade should be the first, maximum the second, and the moisture content no more than 15%. Before starting to use, do not forget that all boards and bars must be treated with an antiseptic.

Heat engineering calculations

Mansard roof - insulation

The construction of an attic is not complete without the use of insulation, most often mineral wool is used for this purpose, it is supplied in slabs or mats. It is also allowed to use polyurethane foam, ecowool, foam, extruded polystyrene foam. Having decided on the material, you need to choose the right thickness, it is important to take into account the height of the rafters, it should be equal to or slightly greater than the thickness of the heat-insulating layer. Provided that mineral wool is used, it is necessary to ensure that there is a ventilation gap, it is a space of 50 mm between the heat insulator (its upper surface) and the roof.

Step-by-step description of the process

We turn to the main thing - how to build a mansard roof of a house with your own hands. To cope with this task, it is important to follow a certain sequence of work. It all starts with attaching the Mauerlat to the wall (if the house is not frame and not wooden), then the rafter system is installed along with struts and racks. Installation of waterproofing and wind protection is not complete. Before laying the outer roof, the sheathing is done. At the end, insulation is carried out from the inside, sheathing of protruding structural elements.

And now a little more detail about some of the stages.

If the installation of the Mauerlat is required, then this is done on the inside of the outer wall. There are several ways of fastening the elements, to a greater extent it depends on what the house is built of. Anchors, pins or staples can be used in the work. In relation to buildings made of foam or aerated concrete, a monolithic belt is made, due to this it is possible to prevent destruction. After the construction of the Mauerlat, the crossbars are mounted (if necessary), the supporting structures are laid, the rafter legs are laid out at a certain interval. Mounts can be made rigid or articulated.
Before you start laying the insulation, try to protect it from negative influences from the outside. We are talking about laying a membrane sheet that protects against wind and moisture, securing the lathing. After that, you can start laying the topcoat, as an option, you can use shingles.
In order to ensure effective thermal insulation at home, the material must be laid without gaps, cracks. If you plan to use expanded polystyrene, the resulting spaces must be filled with sealant / polyurethane foam. Upon completion of the work, the vapor barrier is fixed from below, then the inner lathing, after which you can proceed to the ceiling sheathing. The ideal option in this case is drywall 12.5 mm thick.

To provide access to natural light in the room, as well as tightness, you need to install special skylights. Their feature is the ability to withstand the effects of external precipitation, which are negative. The possibility of high-quality ventilation of the living space is also important. For the installation of windows, it is better to contact a specialist, because they have all the necessary skills.

Positive features of the superstructure

Information on how to build a mansard roof correctly will not hurt anyone, because it is an excellent solution for a building for any purpose. If you give preference to the frame option, you will be able to appreciate its main advantages. For instance:

the structure turns out to be light, which means that it does not heavily load the main building. From this it follows that there is no need for additional strengthening;
compared to stone options, this type of structure is much cheaper;
it is possible to provide a high level of thermal and sound insulation;
the attic can be made of any shape, configuration. mansard roof

And lastly, the consumables used are quite light, so there are no difficulties with lifting them up.

Everyone dreams of expanding the usable area of the home. But the area of the house does not always allow equipping, for example, an extension. One of the best solutions in this case is the construction of an attic roof - an additional footage with minimal investment.

Such a roof is built quite easily and quickly. And with the help of a few friends, you can save on labor.

To build a mansard roof yourself, you need to arm yourself with knowledge in this area to the maximum. Read more about the device of the attic roof. So, mansard roofs are:

- 1 level - the building has outboard consoles, a large area and vertical windows. An attic with a single-level roof extends beyond the level of one of the sides of the house;

- in 2 levels - a project that has a mixed type of support. This type of roof is the most difficult at all stages of construction; it is designed together with the house;
- gable - superstructures for the attic in one level, easy to install. The main disadvantage is the small area and low ceilings;

- gable broken lines - buildings with 4 pitched planes at different angles. A little more complicated than the previous version, but among the advantages is a full-fledged interior.

Different projects of attic roofs almost do not differ from standard pitched roofs and include the following elements:

roof - appearance and protection from precipitation;
lathing - the base for roofing and insulation materials;
ridge - the crown of the rafter structure;
rafters - inclined stiffeners of the entire structure;
Mauerlat - base beams for installing a rafter system;
diagonal bevels - ties for longitudinal beams and vertical posts;
internal beams - supports for ridge girders and / or rafters for structural stability;
insulation - construction of layers of steam, hydro, heat and sound insulation.

Mansard roof in a private house - photo under construction

To erect, for example, a slate roof of this type, you will need:

wood - beams (15, 12, 10), unedged boards, boards 40-50mm by 150mm;
nails - 80 and slate;
wire - annealed (3-4mm) and for stretch marks;
slate;
insulation;
hydro-barrier.

Tools for building a mansard roof, most likely, do not even have to buy:

roulette;
axe;
hammer;
construction stapler;
plumb line;
hacksaw.

The angle of inclination of the roof provides precipitation relief, but takes the height of the room. That is, the smaller the angle of inclination, the larger the area of the room itself will come out. Partially, the usable area of the attic is also reduced due to insulation for the roof. Read which ones exist and how to stack them correctly.

Mansard roof construction technology

The technology for erecting a mansard roof has some subtleties:

- the thickness of the rafters must be more than 250 mm. This is necessary for comfortable laying of the insulating layer of 20 cm. The rafters can be made from glued laminated timber;

- for thermal insulation it is better to use expanded polystyrene or glass - they retain their properties even with an increase in humidity;

- ventilation must be installed between the insulating layer and the roof in accordance with all the rules - with hoods and vents so that the air circulates freely under the surface of the building;

In order for the roof to be of high quality and reliable, it must have excellent ventilation, thermal insulation, and a high-quality rafter structure made of treated wood.

- the inner side of the insulation needs a vapor barrier over the entire surface;

- a layer of hydro-, if necessary, soundproofing is laid out under the roof from the outside of the rafters;

- wood for the entire structure must be treated with special agents from microorganisms and fire, according to the requirements of SNiP;

- if the mansard roof is installed in windy areas, it is worth reducing the angle of its inclination;

- if the house is located in a quiet, windless place, you need to increase the angle of inclination;

- such roofs are covered with ceramic tiles or slate. Metal, due to its low thermal insulation properties, is not recommended;

- for thermal insulation it is necessary to use non-combustible materials;

- the mansard roof provides for the presence of a ladder.

The external staircase will not take up the area of the house, but the attic can only be accessed from the street. Internal - much more convenient, but takes up space in the house. To solve this problem, you can install a ceiling ladder with a hinge or a helical structure. And how to choose the second floor according to GOST, read our instructions.

Phased construction of a mansard roof

Before erecting a roof, you must:

Conduct an examination of the building to determine the maximum load for the walls and foundation.
Develop an attic project.
Obtain permission documents:

from city authorities for construction and reconstruction;
an expert opinion on the house;
permission from all owners.

Rafters of a sloping attic roof - diagram

After designing the roof and the preparatory process, you can start building:

We lay and fasten the Mauerlat around the perimeter of the house - a beam of 100 to 100.
Installing the frame. The racks of the frame will serve as the supports of the rafter structure. For its device, take a bar with a section similar to the section of the longitudinal beams. Vertical posts are placed along the edges of the building and attached to the longitudinal beams using corners and self-tapping screws. We make a jumper on top of each rack.
We mount the rest of the arches. Between the two arches formed at the previous stage of installation, we stretch the cord strictly horizontally. The rest of the arches are installed with a reference to the cord and a step for the rafters. We connect the arch with stamped corners or nail plates as lintels.
We pass to the rafters. We cut their upper ends at a certain angle. On the bases of the beams, we cut out the grooves for mounting on the Mauerlat. The rafters are fixed to the base structure. Then, according to the template, cut the upper rafters and also put them in their places. Also check out more details for the attic.
We mount the crate with boards or plywood sheets.
We lay a layer of steam and thermal insulation. The layers are installed from the inside of the rafters. We fill the crate over the insulation.
On the outside of the rafters, we mount a waterproofing layer.
The last step will be the installation of the roofing material of the selected material. The roof layer is mounted on top of the waterproofing.
Do not forget about ventilation windows, as well as window openings. Of course, a window can only be installed in gables, but two windows are unlikely to provide sufficient lighting.

How much will it cost to build a mansard roof

Consider the prices for materials for the attic roof, given that the construction will be carried out independently.

The price of insulation (mineral wool) depends on the density per cubic meter and the basis:

on fiberglass - 1400-2500 rubles. per cubic meter;
on basalt fiber - 1100-2000 rubles. per cubic meter;
on jute fiber - 10-16 rubles. per running meter.

Roofing materials do not differ much in price:

bituminous tiles - about 340 rubles. per square;
metal tiles - about 250 rubles. per square.

Calculations of the final cost of the building are made based on the area of the mansard roof.

Video

About the construction of a mansard roof with your own hands in the video. About the technology itself clearly and a few useful tips.

A mansard roof is an ideal solution for expanding the area of the house. Having enlisted the support of several people and armed with the knowledge of building a structure, you can quickly build a functional and reliable mansard roof for many years of use.

The mansard roof makes it possible to significantly increase the total living area, while the investment of funds will be minimal. The most common option is a gable broken structure, which is easy to build on your own.

How to make a mansard roof yourself

Living rooms can be arranged under the attic roof. The shape of the building can be different, but in most cases the attic is set up under a roof with two slopes. The optimal solution, which allows you to obtain a significant area of living space, is a broken structure.

A sloping roof is the best option for arranging an attic

Attic roof drawings and calculations

The first step is to decide on the frame scheme. Rafters can be of a layered or hanging type. Slabs rest on the walls of the building. They are mounted in structures where the distance between the walls is less than 6.5 m. Hanging rafters are placed on filly and Mauerlat. If the width of the spans is large, then the rafter system will need to be reinforced with auxiliary bundles.

The main condition for the comfortable construction of the attic is the level of the ceilings - it must be higher than 2.5 m.To ensure a similar height, the break line should be located at a height of more than 2.8 m, taking into account the thickness of the layer of material for insulation and sheathing of the structure. It is also important to consider the thickness of the floor.

An example of a drawing can be seen in the image:

The minimum height of the mansard roof ceilings is 2.5 m

To calculate the expected snow loads, you will need to apply this formula: S = Sg x µ, where S is the snow load, Sg is the weight of the snow cover per 1 m2 of area, µ is a value that depends on the slope of the roof (1.0 - for a flat design with an inclination of 25 °, 0.7 - for a design with an inclination of 25-60 °).

Parameters Sg and Wo can be found in the corresponding SNiP, in the section "Rafter systems". If the roof has a steep slope, the snow load can be ignored.

Roof device

The frame structure includes the following details:

Mauerlat - a support bar that transfers the load from the rafters to the walls of the building;
racks - supporting parts that support the rafter system in an upright position;
floor beams - planks that form half of the attic and the ceiling of the lower floor;
rafters - slats that form the main contour of the roof;
girders - horizontal support parts for rafters;
sheathing - slats or plywood sheets, which are intended for laying roofing material;
filly - strips that are attached along the axis at the bottom of the rafter legs.

The frame consists of a Mauerlat, posts, purlins, floor beams and other elements

The sloping roof differs from the usual construction with two slopes. The difference is that the slopes, which are placed opposite each other, have a special shape: they do not form a straight line, but consist of several slopes, which are fastened to one another at an obtuse angle. The design is also symmetrical.

The edge of the rafters is generally set at an angle of about 60 °. The support posts, which support the rafters, form the framing structure of the inner walls. The upper part of the rafters is mounted at a small angle, it can be from 15 to 45 °. This makes it possible to reduce the consumption of materials, while maintaining the functional properties of the roof and resistance to snow loads.

Vertical uprights, which abut against the floor strips, purlins and crossbars that hold them together, form a parallelepiped. The design limits the dimensions of the attic from the inside. To give the product additional rigidity, you should install struts between the floor slats and the lower rafter legs.

If the roof span is more than 8 m, then you will need to install struts

After the installation of the upper elements to fix the truss and eliminate the sagging of the girders, it is necessary to install the suspended support elements - the headstock. For auxiliary fixation of the lower rafter legs, they must be pulled together with the racks using tacks. The parts are fastened with nails and bolts.

Stages of self-construction of the attic

If a decision is made to make such a structure yourself, it is important to provide for the use of such materials in the project:

roofing material;
vapor barrier;
waterproofing;
insulation material.

The choice of insulation affects such a parameter as the step of the rafters. To reduce the amount of heat insulator, it is best to place the rafters so that the slab or mat fits snugly between them. The type of lathing and its pitch will depend on the choice of material for roofing. You need to pay attention not only to the choice of quality material for insulation, but also to create an effective ventilation system.

Ventilation is equipped by preparing technological gaps

The construction of the rafter system must be carried out using fireproof materials. All parts should be treated with fire protection agents. You will need to prepare the following elements:

wooden bars with a cross section of 100x50 mm;
slats 50x150 mm;
unedged boards;
building level;
self-tapping screws;
nails;
steel wire 4–5 mm in diameter;
plumb line;
roulette;
hacksaw;
axe;
hammer;
sharp knife.

Drafting a project

One of the most important parts of the job is drawing up a project. It is very important to analyze the features of the layout of a private house. It is necessary to determine the dimensions and shape of the structure being erected, as well as provide for the placement of windows and balconies.

All structural elements should be indicated on the project.

In the process of drawing up a project, the following requirements must be taken into account:

It is important to determine in advance what height the attic should be. It should be remembered that the distance from the floor base to the highest point of the structure must be at least 0.5 m.
It is recommended to take into account the heating area and the main elements of the interior.
The attic layout must be expanded. If you plan to install windows, then they must be indicated on the drawing.

Drawing up a drawing must begin with the choice of the shape, determining the section of the rafter legs and the step of their placement. To determine the dimensions of the rafters, the following parameters must be taken into account:

bias;
roofing material;
features of the climate in the region of construction.

It is also important to provide for the required number of rafters in the project. They can be of a layered or hanging type.

Rafters can be hanging or layered

At the end, the number of fixing parts should be determined. In the figure below, you can see some of the data required for the calculation, but drawing up a project is a complex process. It is recommended to entrust this work to qualified specialists.

Installing Mauerlat

The device of the attic roof rafter system should be selected based on the type of roof, as well as on the prepared attic project. A simple option is the double slope design.

The main parts of the double slope roof rafter system are:

linear elements (column, bar system, beam);
plane details (slab, flooring, panel);
spatial elements (vault, shell, volumetric detail).

Before performing work, you will need to thoroughly dry the wood. The first step is to mark and install the Mauerlat. It is fixed to the walls of the building. The part can be made from a bar or a powerful lath. If you plan to build a roof with two slopes, then the Mauerlat fits on the long walls of the building. The element is necessary not only for reliable fixation of the lower part of the rafters, but also for the correct division of the load on the walls and the main part of the structure.

To fix the Mauerlat, you should use metal studs that are attached to a beam made of in-situ concrete.

To fix the Mauerlat, you need to install metal studs

The beam should be in the upper part of the wall. It is also possible to use steel wire embedded in brickwork.

To fix the Mauerlat to the upper crown of the wood wall, you need to use wooden pins. Auerlat requires high-quality waterproofing of wooden beams. Therefore, it is necessary to use roofing material or other material with a water-repellent property.

Before installing the Mauerlat, the base must be covered with roofing material

The installation of a Mauerlat is required if it is planned to erect a roof frame, the rafters of which abut against the upper part of the wall with beveled ends or prepared cutouts.

If you plan to make an attic, the width of which corresponds to the width of the building, the rafter legs should rest with the lower ends against the taken out supporting parts. As supports, it is possible to use powerful beams laid across long walls. The number of supporting elements corresponds to the number of rafters. The beams must be fixed to the walls in the same way as the Mauerlat.

Sequencing:

Frame construction

The mansard roof frame consists of floor beams, rafters, purlins and uprights

As a material, coniferous bars 200x100 mm are often used. Floor slats are placed on top of the Mauerlat with a 30-50 cm indent behind the wall surface or in prepared grooves in the masonry. In the first case, the parts are fixed with corners and self-tapping screws.

Fixing the timber to the Mauerlat can be done using steel corners

To make an even overlap, the planks should be installed in this sequence:

The first step is to fit the extreme details in terms of level.
Next, you should pull the cord and install intermediate elements along it.
The spacing of the beams should be from 60 to 100 cm. The distance of 60 cm makes it possible to mount insulation boards without notching.
To level the beams in height, you can hang them. Another option is to use plank liners.
If the beams are inserted into prepared pockets, their extreme parts must be treated with liquid waterproofing and wrapped with roofing felt.

The racks must be set on the extreme strips:

After the installation of racks, crossbars and girders, you can get a reliable structure that will limit the inner rooms of the attic. To increase its strength, in the future it should be secured with struts and tacks.

Installation of rafters

At this stage, the installation of the lower rafters is carried out:

After that, the upper elements are installed:

The first step is to mark the central part of the roof. This can be done using a post that was previously attached to the Mauerlat and tightening from the end of the roof. The edge of the board should be in the center of the roof. On this board, you need to align the rafter legs.
Next, you need to prepare a template from a 150x25 mm rail. It should be applied to the extreme part of the mounted rail at the required level and to the girder on which the lower rafter legs will rest.
Mark the top and bottom cuts and cut out the template. The fixture is applied in turn to both sides of the roof. This will make it possible to check the accuracy of the marking of the central part. If the rows of racks are placed in parallel, then there will be no difficulties in securing the upper elements - they will have identical dimensions.
According to the workpiece, you need to prepare the required number of rafters. The parts are placed on the purlins and tied in the upper parts using iron overlays or trim strips. In the latter case, self-tapping screws are used as fasteners. In the run, the rafter strips rest on the saw cuts and are grabbed by the iron corners. In order for the parts to stand straight, they are fastened using struts mounted with the lower part for tightening. This method is used to install all the rafters.
Fixation of hanging racks is carried out - pieces of slats 150x25 mm. The upper part of the rail is attached at the place of fixing the rafters, the lower one - to the tightening.

Video: roof truss system of the attic type

Installation of struts and gables

Sequencing:

Construction lathing

Sheathing is needed for:

distribution and transfer of the weight of the roofing material to the rafters;
performing additional fastening of the rafter system;
bases for fixing the roofing material.

The lathing can be made in one or two layers, solid or thinned.

The lathing can be solid or with a discharge

The installation method depends on what material is planned to be used to cover the structure. If a roof is to be erected from slate or metal, the lathing should be made of slats, which are attached to the rafter legs with nails. In this case, the step of installing adjacent strips can be 27-30 cm.

Solid lathing is used in the case of fastening soft material in rolls.

Solid sheathing is required for soft roofing

In this case, moisture resistant plywood sheets or particle boards can be used. It is allowed to use pine wood material - edged planks.

It is important to take into account the fact that when installing such a crate, the material that will be laid must repeat the contours of the outer base. Therefore, the frame structure must be strong and leveled.

In the process of laying out the material, a cord should be used with which the slats or plates will lie flat. Parts should be placed parallel to each other. Before fixing, the material must be treated with an antiseptic composition in order to protect it from rotting, the appearance of fungus and dampness. The workpieces must be even and of high quality. It is recommended to give preference to wood of the 1st and 2nd grade. There should be no knots on it. To prevent the boards from warping, they must first be dried.

The sequence of steps for installing the crate:

Mansard roof waterproofing

The material for the roof does not have thermal insulation properties, so you will need to prepare a high-quality material that will be environmentally friendly for human health. Mineral wool or glass wool is often used. Both materials have excellent sound and heat insulation parameters. It is also important to take into account that if the roof is made of metal, when the insulation gets wet, all its qualities can be reduced to zero. Therefore, it is important to carefully consider the design device.

It will not work to insulate the attic without laying a waterproofing material, so the process should be considered together. A step-by-step guide to waterproofing a structure:

Practice has shown that it is better to protect the insulation with the help of modern materials, for example, Tyvek or Izospan. The use of ordinary polyethylene film gives poor results, as condensation may appear. Experienced craftsmen believe that the structure should not be waterproofed with roofing material.

Before proceeding with the work, you need to decide on the thermal insulation material.

Mineral wool is a fairly popular material used for roof insulation.

The following heat insulators are most commonly used:

glass wool;
mineral wool;
Styrofoam;
foamed glass;
wood shavings;
straw.

The choice of material should be based on four parameters.

Thermal conductivity index. For roof insulation, 0.05 W / m * K or lower is optimal.
Water resistance. The higher the score, the better.
Resistant to fire.
Environmental Safety.

The insulating qualities of mineral wool deteriorate significantly after some time. Also, the material can be damaged under the influence of mechanical stress. However, mineral wool has a low cost, so the material is used quite often. Polyfoam is not afraid of water and has excellent thermal insulation characteristics. If you plan to build a house only from environmentally friendly materials, then you can use foam glass or straw.

Roof Insulation Step-by-Step Guide:

Laying of roofing material and installation of window openings

As an example, the installation of metal tiles will be considered, since this material is used quite often:

The number of windows is determined by the ratio of the usable glazing area to the base of the floor 1:10. For example, if the area of the attic is 100 m 2, then the glazing should be about 10 m 2. When installing windows, you must take into account the following nuances:

Attic finishing

The interior decoration of the attic can be done with wood or plasterboard sheets. If the latter option is used, then after installation, the sheets must be pasted over with wallpaper or painted with water-based paint. In some cases, the attic is divided into several rooms. This can be done using drywall partitions.

If you plan to use the attic often, then the floor and walls can be additionally insulated. This can be done using, for example, mineral wool.

Interesting design options for the attic room

The attic can be made cozy by symmetrically arranging the sofas on both sides. In the attic, you can arrange a long sofa. In the attic, you can equip a place to relax by hanging a hammock. In the attic, you can make not only a living space, but also a bathroom. On the attic floor, you can even make a kitchen. there is no way to arrange a hammock, then this can be done on the attic floor One of the parts of the attic can be completely glazed The attic can be an excellent place for creating a home library Attic walls can be faced with bricks In the attic you can equip a full-fledged living room On the attic you can equip a rest room If the house is located in a beautiful area, the roof can be made panoramic. The bed can be placed facing the window. In the attic, you can make a bedroom with high ceilings. In the attic, you can place a hanging chair. This will make the roof more comfortable.

Video: making a mansard roof

Recently, the mansard-type roof is quite popular among the owners of private houses. To experience all the positive aspects of living in a building of this type, you need to pay due attention to the insulation of the building.

To use the entire possible area, give the house originality and significantly reduce heat loss through the roof - these are the tasks that the attic solves. If there is a certain margin of safety at the foundation in this way, you can turn a one-story house into a two-level one. It is also attractive that a mansard roof was built with your own hands, even without the presence of special construction skills. It is important not to be mistaken with the choice of materials and to do everything according to the rules.

The windows on the regular floor are located in the walls. There are no or almost no walls in the attic. They are replaced by a roof. Therefore, the windows are made special: they must not only transmit light in sufficient quantities, but also withstand wind and snow loads, which are much greater on the roof than on the walls.

Roof windows

When planning an attic, it is worth considering the recommendations of SNiP. They recommend that the window area be at least 10% of the floor area. So if the attic will be divided into several rooms, there should be a window in each.

Of all the methods shown in the photo for arranging roof windows with an attic, an inclined installation is the easiest to implement. In this case, it is necessary to ensure the proper degree of waterproofing of the junction, as well as to use special models with a reinforced frame and reinforced glass - the load on the surface can be significant.

Advantages of a tilted roof window:

more light, less sharp boundaries of light and shadow;
the surface of the roof remains flat, its relief is not complicated;
relatively easy installation.

When planning such a window, it must be remembered that its area increases with an increase in the angle of inclination. At what height it is more convenient to install such a window and how its height increases in centimeters depending on the tilt, look at the photo.

The steeper the slope relative to the floor, the lower the window height should be.

The width of the window frame should be 4-6 cm less than the step between the rafters. Then it can be easily installed without disturbing the structure of the frame. If the window is wider, it is necessary to make a reinforced beam above it, calculate the load.

If you need to have a larger window, it is easier to put two narrow ones side by side. They look no worse than one big one, and there will be fewer problems.

When installing a dormer window, the geometry of the roof becomes more complicated: a valley appears on top and on the sides. Because of this, the rafter system becomes more complex both in planning and in assembly. The complexity of the installation of the roof covering also increases. All valleys are where leaks are most likely to occur. Therefore, everything must be done very carefully here. In regions with a large amount of snow, it is advisable to install snow holders above such windows so that they are not blown away during a sharp descent.

Arrangement of a vertical window-dormer in the mansard roof

The advantage of such a window: you can stand near it in full growth. But they let in less light, the relief becomes more difficult and the roof becomes more problematic.

A recessed window is usually used if you make an exit to the balcony through it. In other cases, this method of arrangement is not the best option: little light enters, the shadows turn out to be very deep, which is tiring for the eye, the geometry also becomes more complicated, although not to the same extent as in the previous version.

The easiest way is to make a window at the end of the attic. In this case, you do not need a reinforced frame or reinforced glass. It is quite enough just high-quality glasses. It is this option that can most often be seen in summer cottages: this is the most inexpensive option, which is easily implemented with your own hands.

Rafter system

When self-building private houses with an attic, usually a broken roof is chosen. It allows you to get a room of a large area, larger than under the gable.

With an equal width of the base (house), an attic room under a broken roof turns out to be larger than under a conventional gable. The rafter system becomes more complex, but the gable roof with an attic under a sloping roof is still more popular.

The construction of the sloping mansard roof is such that the overhangs can be lowered quite low, giving the house an interesting look. But the long overhang of the roof serves not only a decorative role. They also cover the upper part of the wall from precipitation and divert the bulk of the water away from the foundation. Although when planning you need to keep in mind that in strong winds they increase windage. Because of this, it is necessary to use more powerful boards and beams. Therefore, the size of the roof overhang is chosen based on several considerations, the main of which is weather conditions.

Tilt angle

Depends on the roofing material, but most of all - on the region and weather conditions. The classic version is shown in the figure: the lower slopes in relation to the attic floor plane are inclined by 60 °, the upper ones - by 30 °. Based on these data and the parameters of your building, all lengths can be calculated. It is only worth considering that according to SNiP, the ceiling height in the attic cannot be less than 2 m. Then, by definition, it is an attic. A person will feel comfortable if the ceiling is raised to a height of at least 2.2-2.3 m. Based on this, according to the rules of geometry, calculate the required lengths.

In the classic version, the load from precipitation on the side surfaces may not be taken into account. Precipitation will be able to stay only on the upper part, the angle of inclination of which is less than 45 °.

In general, the inclination of the side surfaces usually ranges between 45 ° and 80 °. The steeper the slope, the more windage it has, this must be taken into account: in regions with strong winds, it is better to make flatter roofs. Then wind loads will be perceived much better.

Types of rafter systems of sloping roofs

The construction of a sloping mansard roof is one of the options for the rafter system (the most common)

To make a broken roof frame with their own hands, they most often use pine lumber, grade - at least 2. The choice of the section of the timber and boards depends on the size of the roof, the selected roofing (its weight), the wind and snow load in the region, the step of installing the rafters. All these parameters are taken into account in the calculation. The technique is prescribed in SNiP 2.08.01-89 and TKP 45-5.05-146-2009.

One of the options for constructing a frame with hanging rafters

Above in the figure will lead a drawing of a frame with hanging rafters. It can be realized only if the base of the upper triangle is no more than 4.5 meters (in this case, this is the width of the attic room). If more, you will have to make layered rafters, which should rest on the load-bearing wall in the middle (the attic will turn out to be divided into two parts by a row of beams).

Another version of the upper part is shown in the photo below (the picture is clickable). In this case, the side rafters are reinforced with struts. They significantly increase the rigidity of the system.

There is a second way to achieve a similar effect - to establish contractions - in the figure, they are only outlined with barely visible lines. The length of the lateral rafter leg is divided by three, and contractions are set in these places. They will be needed if the roofing will have a solid weight.

A variant of the device for the rafter system of a broken roof - with struts that increase the rigidity of the system

For a small building in terms of dimensions, the roof frame can be generally simple: at the top there are two hanging rafter legs, a tightening, floor beams, racks and side rafters (pictured below).

The device of the rafter system of a broken attic roof for a small house

How to calculate a sloping roof

The broken roof attic of a small house (no more than 6-7 meters wide) has been built so many times that, based on experience, we can say which materials are worth using. Many parameters are dependent on other materials. For example, the step of installing the rafters is tied to the parameters of the insulation. In order to have as little waste as possible during insulation, installation was easier, it is necessary that the distance from one rack to another be slightly less than the width of the insulation (by 20-30 mm). So, if you are going to use mineral wool, its width is 60 cm. Then the racks must be installed so that the gap between two adjacent ones is 57-58 cm and no more.

The width of the board for the rafter leg is again determined based on the insulation. For the middle zone of Russia, the required thickness of basalt wool is 200-250 mm. That's not all. In order for the insulation to dry out, a ventilation gap of 20-30 mm is required (without it, condensation will gradually rot the wood and render the mineral wool unusable). In total, it turns out that, at a minimum, the width of the rafter leg should be 230 mm. Board thickness - at least 50 mm. This is in regions with light winds and not very heavy snowfalls. To summarize, for all rafters - ridge and side - a board of 230 * 50 mm is required.

If lumber with such characteristics turns out to be too expensive, it will be possible to make insulation in two directions: part along the rafters, partly, filling the crate, across. It is possible to lay at least 100 mm of basalt wool, therefore, you can take a standard board of 50 * 150 mm and leave 50 mm for the ventilation gap, or order a non-standard 130 * 50 mm. Look what is more profitable in terms of money.

For racks and beams, it is better to take a bar of at least 80 * 80 mm, better - 100 * 100 mm. Especially in areas with difficult weather conditions - with heavy snowfalls or strong winds.

Order a more accurate calculation from specialists. This is a long-term process, which consists of collecting loads from the roofing material, the structural elements themselves, wind and snow loads. After that, according to a certain formula, there is a selection of elements. For more information on how the calculation is carried out, see the next video.

Do-it-yourself mansard roof: installation procedure

The Mauerlat device on mansard roofs is no different from the standard version. If or logs, the upper crown can be used as a Mauerlat. It is only pretreated with an impregnation with high protective properties.

If the wall is made of foam blocks, a reinforced monolithic belt is arranged on top of it. On a brick wall or folded from shell rock, other similar materials, the device of such a belt is optional. Waterproofing is laid on the wall in two layers, and on top - a timber treated with an antiseptic - 150 * 150 mm or a log. It is secured with embedded pins.

When assembling all elements, long nails are used - at least 150 mm in length. In the most critical places, it is better to connect three or more elements with bolts or studs with double-sided threads. It is advisable to reinforce all joints with steel plates or corners.

The first way

The installation of the attic roof rafters is done in two ways. First: they collect the parts on the ground, then they are raised up in finished form. There, the first to expose the extreme structures, which will become gables. They are placed vertically, secured. It is often more convenient to secure them with long bars nailed to the wall (temporary). The following assembled structures are inserted into the prepared recesses in the Mauerlat (they are made with the required pitch). They are exposed strictly vertically, carefully fixed. If necessary, install additional temporary spacers that fix them in the desired position. Side beams are installed.

How to build a sloping roof in this way, to collect nodes, see the video below.

Second way

The second method - the construction of a sloping roof is carried out sequentially collecting elements right on the spot. This method is more convenient if the structure is large and when assembled it can only be lifted using special equipment (crane).

First, the floor beams are laid. Racks and puffs are attached to them, temporary spacers are placed to hold them in the vertical direction. Next, the rafter upper and side legs are assembled, puffs and jibs are installed.

During installation, the following sequence of actions is observed: first, the extreme elements are installed and set in the desired position, securely fixed. Use temporary spacers if necessary. A fishing line, rope, lace is pulled between them, which will serve as a guide for the installation of all subsequent elements. This simple move allows you to get perfect geometry (do not forget to check the slope angle, verticality or horizontalness).

On top of the racks, puffs are attached - bars, to which the side rafters are then fixed and on which the tightening of the upper triangle is installed. Puffs are fastened with metal corners. Since the beams are long, they sag. This is further eliminated - after the installation of the upper rafter legs - using vertical beams of fixed or adjustable height. And temporarily they can be propped up with racks (so as not to pull the entire system).

To make it easier to maintain the desired angle when installing the side rafter legs, templates are made according to which the cuts are made. But since the geometry of DIY buildings is rarely perfect, adjustments may be needed. To check the resulting angle of inclination, another template is knocked down from several boards, which checks the correct installation.

If the standard length of lumber - 6 meters - is not enough, or they order the required length (expensive) or build up. When building up, two boards at least 0.6 meters in size are nailed to the junction (30 cm on each side of the junction). They are nailed on both sides or bolts are used.

A reliable way to build rafters. The length of the "patch" - not less than 60 cm

After installing the side rafters, it remains to install the upper ones. For them, a template is also made, it is first filed on the ground, and installed at the top.

The top can be made in different ways. Its structure depends on the width of the base. How to do it, see the photo below.

Since the device of a mansard broken roof does not provide for the presence of a ridge, a bar is packed for tightening in the middle, to which the slopes are attached, fixing the triangle in the required position.

Nodes and their drawings

When installing the rafter system, questions may arise about the assembly of nodes - the intersection and connection of several structural elements. In the photo you see drawings of key connections.

The second option is to connect the side layered rafters and the upper triangle. Bolts are used for more reliable fastening.

How to make a do-it-yourself fastening of the upper tegonal and rafter legs on the attic roof

The methods of attaching the rafter legs to the Mauerlat or, as in this case, to the side beam are shown in the figure below. To make it easier to mount a heavy element, a stubborn board (bar) is nailed to the rafter from below, which limits its movement: the board rests on the edge and does not allow it to fall below.