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Construction of an attic using frame technology. How the rafter system of an attic roof works: a review of structures for low-rise buildings How to make an attic frame

A do-it-yourself mansard roof built over a house allows you to increase the total living space with minimal financial investment. The most popular options include a gable sloping roof, the installation technology of which is not complicated.

Project development

"Broken" roofing slopes at different angles, you can increase the volume of space under the attic roof. The broken structure, like other types of attic roofing, is more massive and heavier than a standard gable roof, which should be taken into account when installing attic floor in the process of renovating a house. It is first necessary to examine the condition of the foundation and walls of the structure to determine whether they can withstand increased loads. If the installation of a massive attic structure is planned at the stage of preparation for DIY construction, this should be taken into account when developing the design of the foundation and walls of the house.

You should be careful when creating a mansard roof project, since errors in calculations or incorrectly selected parameters of the rafter system elements can lead to damage to the roof itself, and in some cases, to the walls of the house during operation.

It is recommended to entrust the development of a mansard roof project to professionals. It is also possible to use special computer programs that perform calculations optimal angle roof slope and other parameters. All calculations are performed in accordance with the SNiP document “Loads and Impacts”.

When choosing an attic project, the construction of which can be done with your own hands, you first need to pay attention to the dependence of the room parameters on the angle of inclination of the roof. The living space must have a height of more than 2.2 meters. If the roof slopes are straight, then their angle of inclination seriously affects the width of the room.

A broken attic roof allows you to maximize the expansion of the room, providing the required ceiling height along its entire width. In this case, the side (lower) rafters are located at an angle of about 60 degrees, and the angle of inclination of the upper ones can be chosen at your discretion, based on aesthetic preferences, as well as snow and wind loads characteristic of the construction area.

Roofing pie and other elements

If you are planning to make an attic roof with your own hands, it is necessary to include in the project the use of certain materials for installing the roofing pie. They include:

• waterproofing;
• vapor barrier;
• insulation;
• roofing material.

The choice of insulation affects such a parameter as the pitch of the rafters - in order to save thermal insulation material It is recommended to position the rafters so that the slab or mat fits tightly between them. From choice roofing covering depends on the type of lathing (solid or sparse) and the spacing of the sparse lathing. It is worth noting that the installation of the roof of the attic floor provides for the creation of not only high-quality insulation, but also effective ventilation of the roofing system.

Materials and tools

To ensure safety, the construction of the rafter system and roof should be carried out using fireproof, environmentally friendly materials. Wood materials are treated with fire and bioprotection agents.

To build a rafter system for a private house with your own hands you will need:

• wooden beam with a cross section of 50×100 mm;
• board 150×50 mm;
• unedged board;
• 80 nails, self-tapping screws and other fasteners;
• annealed wire (diameter 3-4 mm);
• level;
• plumb line;
• roulette;
• hacksaws;
• axes;
• hammers;
• sharp knives carpentry

Using high-quality tools simplifies and speeds up installation wooden structures with your own hands. Step-by-step instructions for carrying out the work can be found in the video.

Mauerlat device

The base of the rafter system of the attic roof is a mauerlat made of timber or strong boards. A gable roof requires laying a mauerlat on the long walls of the house. The Mauerlat not only allows you to securely fasten the lower part of the rafters, but also helps to distribute the load evenly when it is transferred to the walls and foundation of the building.

To secure the Mauerlat board or beam, metal pins are used, fixed in a monolithic concrete beam made in the upper part of the wall, or annealed wire embedded in the brickwork. When attaching the Mauerlat to the upper rim of a wooden wall, wooden dowels are used. The installation of a Mauerlat requires high-quality waterproofing of wooden beams. For this purpose, roofing felt or other durable materials with water-repellent properties can be used.

Installation of the Mauerlat is necessary if you intend to build a roof frame with your own hands, the rafters of which rest against the upper part of the wall with a beveled end or a special cutout. If an attic is designed, the width of which actually corresponds to the width of the house, the rafters rest with their lower end against the outer supports. The supports are powerful beams laid across the long walls. The number of supports must correspond to the number rafter pairs. The beams are attached to the walls in the same way as a Mauerlat, and waterproofing is also used.

The Mauerlat or support beams must be securely fastened to the walls, as these elements prevent the roof from moving under strong wind loads.

Construction of the supporting structure

The construction of the frame of a sloping mansard roof begins with laying supports under the racks, which must be positioned strictly symmetrically relative to the axis of the building. The distance between the supports is equal to the width of the future attic. First of all, U-shaped arches are installed on the gables of the structure. Each arch consists of two support posts connected by a lintel. To make racks, a beam is used, the cross-section of which must be no less than the cross-section of the support underneath.

The racks are installed plumb, strictly vertically. A jumper is attached to them, the horizontalness of which should be checked during installation. Based on the dimensions of the first arch, a second one is made on another front. It is important to level the structure. A cord is stretched between the U-shaped arches, which must be positioned strictly horizontally. If necessary, one of the arches is dismantled and adjusted exactly to size. Focusing on the stretched cord, you should install the remaining arches. Their number and pitch depend on the designed pitch of the rafters, since the upper end of each rafter is attached to the corresponding rack. This provides the necessary rigidity of the attic roof frame.

The uprights of U-shaped arches can be attached to the support with metal brackets, nails or tenon joints. You can learn about the main methods of connecting rafter structure elements from the video instructions. To ensure the verticality of the racks under the load that the roof will experience during operation, it is recommended to additionally install braces. The arches in the upper part are connected to each other by lintels parallel to the long walls of the house.

Installation of rafter legs

DIY construction sloping roof involves the use of two types of rafter legs. The lower rafters are located under very acute angle, connecting the racks to the Mauerlat or the ends of the external transverse supports. The upper gable rafter structure is mounted on an arched system.

Before installing the lower rafter legs, you must carefully mark the location of their installation on the Mauerlat. The rafters closest to the gable are installed first. Trimming the rafter legs is carried out in such a way that the cut of the upper edge of the board fits at the required angle to the stand, and the lower cut rests against the mauerlat or remote support. If, according to the project, the attic roof is made with overhangs, a specially shaped cutout is made in the lower part of the rafter leg: with the horizontal part of the cutout, the rafter rests on a support. The rafter is secured with nails or staples. It is recommended to additionally strengthen the connections of the legs with the Mauerlat or external support with burnt wire with a diameter of 3-4 mm. All lower rafters are installed according to a similar scheme.

If we are building a house whose length exceeds 8 meters, it is recommended to install a rafter system with ridge beams. This device allows you to evenly distribute the load over the entire frame. In this case, racks are installed in the center of the gables, the verticality of which is checked with a plumb line, and a ridge beam is mounted strictly horizontally on them. It is important to correctly determine the height of the ridge, since the angle of inclination of the upper rafters directly depends on this. The rafter legs rest against the ridge beam with their upper cut ends, and with their lower ends against the supporting arched structure.

The upper rafters of the attic roof can be an L-shaped structure. Rafter legs can be connected end-to-end using a wooden or metal fastening plate, or by cutting into half a tree, using bolted connection. It is recommended to fit the first pair of rafters locally, which are then dismantled and used as a template. The prepared trusses are installed in the standard order - first the outer ones, then the rest with constant leveling.

At the last stage of creation roofing structure Do-it-yourself installation of sheathing, laying waterproofing, creating a ventilation gap, and installation of roofing. Thermal insulation and vapor barrier are attached from the inside, and the sheathing is attached. In the video you can get acquainted with the technology of work in detail.

Using all possible space, giving the house originality and significantly reducing 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. Another attractive thing is that you can build an attic roof with your own hands even without special construction skills. It is important not to make a mistake with the choice of materials and do everything according to the rules.

Windows on a regular floor are located in the walls. In attics there are no or almost no walls. They are replaced by a roof. That’s why windows are made special: they not only must let in sufficient light, but also withstand wind and snow loads, which are much greater on the roof than on the walls.

Dormer windows

When planning an attic, you should take into account the recommendations of SNiP. They recommend making the window area no less than 10% of the floor area. So if the attic is divided into several rooms, each should have a window.

Of all the methods shown in the photo for installing skylights with an attic, inclined installation is the easiest to implement. In this case, it is necessary to ensure the proper degree of waterproofing of the junction, and also to use special models with reinforced frames and reinforced glass - the load on the surface can be significant.

Advantages of a sloping roof window:

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

When planning such a window, it is necessary to remember that its area increases with increasing angle of inclination. At what height is it more convenient to install such a window and how its height increases in centimeters depending on the inclination, look at the photo.

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

The width of the window frame should be 4-6 cm less than the pitch 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 and calculate the load.

If you need to have a larger window, it is easier to place 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 roof geometry becomes more complicated: a valley appears on top and on the sides. Because of this, the rafter system becomes more complex both during planning and during assembly. The complexity of laying the roof covering also increases. All valleys are the places where leaks are most likely to occur. Therefore, everything needs to be done very carefully. In regions with a lot of snow, it is advisable to install snow guards over such windows so that they are not blown away in the event of a sudden meltdown.

Installation of a vertical dormer window in an attic roof

The advantage of such a window is that you can stand next to it at full height. But they let in less light, the terrain becomes more complex and the roof becomes more problematic.

A recessed window is usually used if there is access to a balcony through it. In other cases, this method of arrangement is not the best option: little light gets in, the shadows turn out to be very deep, which is tiring for the eye, the geometry also becomes more complex, 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, a reinforced frame or reinforced glass is not needed. Just high-quality glass is quite enough. This option is most often seen on country attics: this is the most inexpensive option, which you can easily implement with your own hands.

Rafter system

At self-construction In private houses with an attic, a broken roof is usually chosen. It allows you to get a room of significant area, larger than under a gable.

With the same width of the base (of the house), the attic space under a sloping roof is larger than under a regular gable roof. The rafter system is becoming more complex, but a gable roof with an attic under a sloping roof is still more popular

The design of the sloping mansard roof is such that the overhangs can be lowered quite low, giving the house interesting view. 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 one 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 plane of the attic floor are inclined by 60°, the upper slopes by 30°. Based on these data and the parameters of your building, you can calculate all lengths. Just take into account that according to SNiP, the ceiling height in the attic cannot be less than 2 m. Then, by definition, this 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 can only be retained on the upper part, the angle of inclination of which is less than 45°.

In general, the inclination of the side surfaces usually varies between 45° and up to 80°. The steeper the slope, the greater the 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 for sloping roofs

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

For making a frame sloping roof with their own hands, they most often use pine lumber, grade no lower than 2. The choice of cross-section of timber and boards depends on the size of the roof, the selected roofing (its weight), wind and snow loads in the region, and the pitch of the rafters. All these parameters are taken into account in the calculation. The methodology 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

The figure above shows a drawing of a frame with hanging rafters. It can only be implemented 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 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 side rafter leg is divided by three, and contractions are established in these places. They will be needed if the roof covering will have a significant weight.

Option for installing a sloping roof truss system - with struts that increase the rigidity of the system

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

Construction of a rafter system for a broken mansard roof for a small house

How to calculate a sloping roof

The attic sloping roof of a small house (no more than 6-7 meters wide) has been built so many times that, based on experience, we can say what materials should be used. Many parameters are dependent on other materials. For example, the installation step of the rafters is tied to the parameters of the insulation. To ensure that there is as little waste as possible during insulation and installation is simpler, it is necessary that the distance from one rack to another be slightly less than the width of the insulation (20-30 mm). So, if you are going to use mineral wool, its width is 60 cm. Then the racks need to 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 central zone of Russia, the required thickness is basalt wool is 200-250 mm. That's not all. In order for the thermal insulation to dry, 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 the minimum width of the rafter leg should be 230 mm. The thickness of the board is 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 do the insulation in two directions: partly along the rafters, partly, filling the sheathing, across. You can lay a minimum of 100 mm of basalt wool, therefore you can take a standard board 50*150 mm and leave a 50 mm ventilation gap, or order a non-standard 130*50 mm. Look at what is more profitable for the money.

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

Order a more accurate calculation from specialists. This is a long process consisting of collecting loads from the roofing material, the structural elements themselves, wind and snow loads. After which, according to a certain formula, elements are selected. For more detailed information on how the calculation is carried out, see the following video.

Do-it-yourself mansard roof: installation procedure

The design of the Mauerlat on mansard roofs is no different from the standard version. If or logs, you can use the upper crown as a mauerlat. It is only pre-treated with impregnation with high protective properties.

If the wall is made of foam blocks, a reinforced monolithic belt is placed on top of it. On a brick wall or made of shell rock, others similar materials, the device of such a belt is not necessary. Waterproofing is laid in two layers on the wall, and on top is a timber treated with an antiseptic - 150 * 150 mm or a log. It is secured with embedded studs.

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

First way

Installation of attic roof rafters is done in two ways. First: they assemble the parts on the ground, then in finished form lift up. There, the outer structures, which will become pediments, are put up first. They are placed vertically and secured. It is often more convenient to secure them with long bars nailed to the wall (temporary). The following are inserted into the prepared recesses in the Mauerlat (they are made with the required step): assembled structures. They are positioned strictly vertically and carefully secured. If necessary, additional temporary spacers are installed to fix them in the desired position. Side beams are installed.

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

Second way

The second method - the construction of a sloping roof is carried out sequentially by assembling elements directly on site. 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. Stands and ties are attached to them, and temporary spacers are installed to hold them in the vertical direction. Next, the upper and side rafter legs are assembled, and the tie rods and jibs are installed.

During installation, the following sequence of actions is observed: first, the outermost elements are installed and adjusted to the desired position, and securely fastened. If necessary, use temporary spacers. A fishing line, rope, and cord are stretched between them, which will serve as a guide for the installation of all subsequent elements. This simple move allows you to get the ideal geometry (don’t forget to check the slope angle, verticality or horizontality).

On top of the racks, tie-downs are attached - bars, to which the side rafters are then fixed and onto which the tie-down of the upper triangle is installed. The ties are secured using metal corners. Since the beams are long, they sag. This is later eliminated - after installing the upper rafter legs - with the help of vertical beams of fixed or adjustable height. And temporarily they can be supported 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 cuts are made. But since the geometry of buildings built with your own hands is rarely ideal, adjustments may be necessary. To check the resulting angle of inclination, another template is knocked down from several boards, which is used to check the correct installation.

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

A reliable way to build rafters. The length of the “patch” is at least 60 cm

After installing the side rafters, all that remains is to install the top ones. A template is also made for them, pre-cut on the ground, and installed on top.

The top part can be made in different ways. Its structure depends on the width of the base. How to make it, look at the photo below.

Since the structure of the attic sloping roof does not provide for the presence of a ridge, a beam is placed in the middle to tighten it, to which the slopes are attached, fixing the triangle in the required position.

Nodes and their drawings

When installing a rafter system, questions may arise regarding the assembly of nodes—the intersections and connections of several structural elements. In the photo you see drawings of key connections.

The second option for connecting the side layered rafters and the upper triangle. Bolts are used for more secure fastening.

How to make a do-it-yourself fastening of the upper tee and rafter leg on an attic roof

Methods for attaching 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 thrust board (bar) is nailed to the bottom of the rafter, which limits its movement: the board rests against the edge and does not allow it to sink lower.

If you want to maximize usable area at home, without spending exorbitant amounts of money, you should definitely consider projects with an attic. The experience of developers suggests that this is the optimal way to plan economy class housing, because one square meter Living space in it is several times cheaper than in two-story buildings. There is a misconception that the attic is only suitable for seasonal use in the warm season.

However, it is erroneous, since a high-quality insulated sloping attic roof perfectly retains heat in winter, its temperature regime is no less comfortable than in the heated rooms of the first floor.

Even without additional thermal insulation, the attic is a kind of “air cushion” that maintains the optimal temperature inside the house.

A broken mansard roof is considered technically complex design, advising you to entrust its construction to a professional team. However, a person who is familiar with roofing work using the example of a traditional gable roof is quite capable of mastering its construction with his own hands, with the help of two auxiliary workers and assistants. The main thing is to understand that this is a process that requires a serious approach, which it would be reckless to start without preliminary calculations.

Types of mansard roofs

An attic is a heated or cold space under the roof that is used as living space. According to building regulations, in the attic room it is necessary to equip windows for natural light and ceilings of sufficient height for a person.

Rooms under the roof in which these conditions are not met are called attics. Suitable for attic installation the following types roofs:

broken roof

Installation of a mansard roof suitable for habitation requires mandatory thermal insulation, the organization of natural lighting using attic or vertical windows and forced ventilation.

Advantages of a broken structure

Of course, you can even equip an attic by building an ordinary one with your own hands triangular roof. But due to the steepness of the slopes, for the ceiling to work, the height of such a roof must be very large. This is not economical, and also impractical, because a roof with a variable pitch angle allows you to use the available space more efficiently.

More flat top part makes ceilings higher. According to building codes, if the distance from the floor to the ridge connection is less than 2.5-2.7 meters, the room is not considered residential, it cannot be called an attic, it is rather just an attic.

• The sloping roof design has the following advantages:
• Possibility of installing higher ceilings.
• High level of protection from precipitation and wind.
• Light snow falling off the slopes.
• Helps conserve heat.

Rational use of under-roof space.

Construction stages

Creating a Project

When drawing up a project for a broken mansard roof for construction with your own hands, it is better to draw up drawings with different projections, which will comprehensively show the location of its elements. Based on the length and width of the house, you need to determine the size of the attic space, as well as the roof. First of all, the geometry of the slopes is built: In order for the project calculations to be correct, it is important to accurately take primary measurements, as well as maintain scale. Can make design easier computer programs , in which you just need to enter the dimensions of the building and the desired type of roof; they perform all the rest of the work automatically. If you have access to this software

no, it’s better to use ready-made projects.

Calculation of the rafter system

Rafters are the main supporting elements of a sloping attic roof, a kind of its backbone. They are subjected to enormous loads, so special requirements are placed on them.

• The choice of the cross-section of the rafter legs does not occur randomly, but in accordance with the installation pitch, the distance between the supports, and the values ​​of the wind and snow load. If the first three indicators can be easily determined from the drawing, then the last two require special explanation.
• The territory of Russia is divided into 8 zones with different snow loads. For each specific roof, this value is adjusted by the angle of inclination of its slopes. Since the slope of the slopes is different, two indicators are calculated, respectively, the upper and lower rafters may have different sections.
• The values ​​of these two indicators are summed to determine the total load. Numbers should be rounded to big side to provide a small margin of safety. Based on them, the required cross-section of the boards is determined using reference tables.

Mauerlat installation

Start of work on equipping a sloping mansard roof - Mauerlat installation, durable timber measuring 100x100 mm or 150x150 mm. It is fixed to the end of the side external walls.

Its main task is to distribute the weight of the roof structure, transfer it to the foundation, and also protect the slopes from tipping over. The Mauerlat is laid along the top of the wall over pre-laid waterproofing, which is used as roofing material folded in half or several layers of a special film.

Fastening is carried out using metal pins; they must be placed in concrete screed. If we are talking about do-it-yourself roof reconstruction, it is installed anchor bolts to the wall to a depth of 15-17 cm.

For lumber, as well as log houses wooden dowels are used. Please note that installation is flush.

Assembling the rafter system

Assembly rafter system of a sloping mansard roof occurs in the following order:

Completing the above points forms one roof truss. The rest are installed in the same way in increments of 60-120 cm.

Waterproofing and roofing works

When the DIY installation work is completed, you need to organize its waterproofing. To do this, you need a waterproofing film or membrane, which is usually produced in the form of a roll.

Fasteners are selected depending on the type of material. For tiles, galvanized self-tapping screws with rubber heads are used, which, during the tightening process, are deformed in such a way that they waterproof the hole.

In order to speed up the process, you can use a screwdriver. Shinglas or ondulin are fixed with nails 100 mm long. After finishing roofing works gables and overhangs of the attic sloping roof are decorated.

To summarize, we can say that a broken mansard roof will help you expand the area of ​​your house with your own hands. You can build it with your own hands, however, this will require special skills and costs, which will undoubtedly pay for themselves.

Video instruction

A mansard roof is an excellent option for obtaining a sufficiently large living space

When building a private house with an attic, it is important to correctly design the structure and size of the roof. After all, the attic is a living space in which various processes occur: air evaporation, heating of the room. This has its effect on the roof. On the other hand, the roof must fulfill its main purpose - to reliably protect from bad weather and retain heat inside.

Therefore, it is important to obtain a high-quality design and calculations before starting construction. Calculations must be carried out by a specialist with experience in designing such objects. Even small errors can lead to incorrect load distribution of load-bearing units and elements. Excessive roof weight that exceeds the strength of the rafters can lead to a weakening of the overall structure and dire consequences.

But before we dwell in detail on how to correctly calculate the size, area and other parameters of the attic, let’s consider the common types of attic roof structures.

Types of mansard roofs

The rafter system and its elements are different for different types of attic roofs of private houses. The roof must be light so as not to load the walls of the houses, while the reliability and strength of the structure must correspond construction requirements standards

Shapes of pitched roofs

The following structures are distinguished by types of mansard roofs:

1. Gable. Two slopes and two pediments.
2. Broken. Having two or more planes located under different angles tilt It is much more difficult to erect a broken roof.
3. Hip. With stingrays triangular shape, covering the gables.
4. Half-hip. The slopes of the facades cover part of the pediment area.
5. Dome. Typical for houses with a round or polygonal structure.
6. Vaulted. With an arched pediment projection.

In addition, roof structures are divided according to design features into ventilated and non-ventilated. This or that option is chosen depending on the climatic characteristics of the region and the design of private houses.

Advice!

At large quantities precipitation, high humidity, roofs with natural ventilation should be preferred. In addition, the air layer inside plays the role of additional insulation.

Designs without natural ventilation more often used in dry climate zones.

A private house with attic roof

The basis of the roof is the rafter system

The main and most important element of the roof is its frame or rafter system. It bears the main load, determines strength and reliability, the service life of the entire roof and how often it will have to be repaired will depend on it.

Therefore, installing a frame is the most labor-intensive process in constructing an attic. The main influences on the rafter system are the loads resulting from the mass of the frame itself, the weight of the snow cover and the effects of wind pressure. In this regard, calculations of loads on rafters must be carried out.

The strength and durability of the entire building depends on the correct calculation of the rafter system, loads and all connection points. An important requirement is the minimum weight of the frame structure. To keep the load on the walls and foundation small, materials with the lowest specific gravity should be included in the project.

Rafter system of a house with an attic

Area calculation

If you plan to use the attic as a living space, it is important to calculate its usable area. For calculations, an important parameter is the total area of ​​the attic space and its useful volume. The latter is calculated using lines connecting the points where the height from the floor to the ceiling plane is 90 cm. The rest of the space is generally considered non-living, suitable only for organizing closets and storage rooms.

The total area is taken from the house and attic plans. The roof area is calculated based on the total area internal structures. The entire roof frame can be represented as a set of elements with different geometries. By calculating the area of ​​such figures separately and adding the values, you can get the total area of ​​the roof structure of the house. This value is necessary not only for further calculations of the strength and weight of the structure, but also for calculations required quantity materials.

Calculation of the area and geometry of the attic premises determine the ratio of the additional area to the underlying floor of the building

Attic roof project

As mentioned above, the key to a reliable and durable roofing structure must be a well-designed project. You can use a standard, ready-made attic roof project, which no longer requires additional calculations. This will speed up work and reduce design costs, but if construction is planned according to individual project, a detailed calculation will be required.

Important!

In addition to calculations, the project must contain information about the design of the rafters, a diagram for installing beams, calculation of its own weight and the expected load of natural factors (wind, snow, rain).

In order to calculate and draw up a competent project, it is necessary to provide for the resistance of all elements to temperature changes.Typically, a project consists of several sections and drawings. It contains calculations and all information about the roof structure:

• first of all, the project determines the main parameters - the shape of the roof, its dimensions, the slope of the slopes, the presence of a pediment;
• the second, and no less important point, is a list of all materials for each unit, indicating their quantity;
• a separate section should be devoted to calculation load-bearing structures indicating the cross-section of the rafter beams, the dimensions of the floor elements and other components;
• drawings with different projections and details of the main components;
• section with calculations thermal properties designs and instructions on insulation and waterproofing with a list of recommended materials;
• recommendations for roofing material based on calculation of maximum loads on the structure.

Calculation of the slope of the slopes

Determining the size of the roof is influenced by its slope. The angle of inclination of the slopes is great importance when building a house. An improperly constructed roof can be destroyed by strong winds if it is built too high. Conversely, if the slope is insufficient, this can lead to the accumulation of snow mass, which will also lead to destruction. Therefore, when calculating the slope of the slopes, local climatic conditions and proposed roofing materials (their weight). As a rule, in snowy areas, peaked roofs are built so that the snow slides down the floor with its weight. And in warmer areas, flat structures are common, reducing windage with an extended overhang.

When starting a specific calculation of the slope of the slopes, we take as initial data:

• The estimated height of the living space in the attic (desired, but not less than 2.5).
• Weather conditions of the area - average amount of precipitation, maximum possible wind force.
• Planned weight and features of the roofing material.
• Type of roof according to the project.

For a gable structure, the slope of the slopes is considered optimal at 45 degrees or more. For a broken structure, the optimal angles are 60 degrees for the bottom slope and 30 degrees for the top. This will allow you to create a room inside that is comfortable for living.

Installation of the attic frame

Before starting the construction of the attic, when the walls of the building have already been erected, it is necessary to lay a 10x10 or 15x15 cm beam along the top of the walls to support the rafter system. This design is called Mauerlat, in chopped wooden house they can serve as the upper crown. If the house is built of brick or concrete, a layer of waterproofing (for example, roofing felt, preferably in two layers) must be laid under a wooden Mauerlat. The main task of the Mauerlat is to uniformly distribute loads on the walls of the house. The timber can be covered with cladding similar to the façade.

1. We begin the installation of the rafter system with the installation of floors. We lay the beams, starting from the outer ones, strictly checking the horizontalness. It is recommended to keep the pitch of the beams at 50-60 cm. The beams should have an extension beyond the walls of approximately 30-50 cm, which will serve as a cornice. We fix it with the Mauerlat using nails and a metal corner on screws.
2. Let's start installing the frame. The vertical support posts are installed first. During installation, we secure them with temporary spacers. Starting from the corners, place the rest at a distance of no more than three meters. The height of the racks must be indicated in the project; it will determine the parameters of the entire structure. At the upper end of the racks we attach purlins (boards 15x5 cm).
3. On the purlins, tie-downs (beam 20x5 cm) are installed, secured with an angle. The task of the puffs is to tie the side girders together. To avoid significant deflection of the tie rods, they must be secured in the future with hangers to the roof rafters. At the installation stage, deflection can be avoided by using temporary supports.
4. We install the rafters. Before installation, it is necessary to make a template in the form of a 15x2 cm board. The template sets the same cut angle at the junction of the rafters with the Mauerlat at the lower end and the upper end with the purlin.
5. The layered (lower) rafters are fastened to the side purlins with nails, and to the mauerlat with metal plates or staples.
6. We proceed to the installation of hanging (upper) rafters. We also prepare a template and cut all the boards according to the template. Attic construction does not provide for a ridge, so additional rigidity should be given by installing struts.
7. We install tie-downs on the upper rafters.
8. In general, the frame of the rafter system is ready. Next, you can sew up the gables, leaving openings for the windows if they are provided for in the project.
9. We make the sheathing. The design of the sheathing depends entirely on the type of roofing material determined by the project. If soft roll roofing(for example, ondulin), we do continuous sheathing. For metal tiles or corrugated sheets, sparse lathing is required. Right choice and proper installation will affect the quality of the roof and its reliability.

Further work is related to insulation and insulation of the attic roof.

The basis of the attic roof is its frame

Advice!

In cases where the roof slope is more than six meters (the length of a standard board), it is necessary to order a board for the rafters required length or splice the rafters to the right size. At the joints, it will be necessary to install additional support posts.

Roof insulation

To create an atmosphere suitable for living in the attic, the roof must be reliably and efficiently insulated. In addition, vapor barrier and waterproofing films are laid together with insulation. To prevent leakage from the outside and accumulation of condensate from the inside, special modern materials. Thus, a “layer cake” is formed, laid between the roofing and the attic room. Such a “pie” should include the following layers:

1. Vapor barrier. Special, airtight film materials laid from the inside of the attic with sealing of the joints. The purpose of this layer is to prevent moisture from penetrating into the upper layers of the “pie”.
2. Warming. Foam plastic or penoplex boards, mineral wool, eco wool, etc. are used as heat insulators. Laying is done with an overlap or with subsequent sealing of the seams with construction foam.
3. Waterproofing. Special film membranes that protect the insulation from precipitation and prevent the formation of condensation. They are laid along the rafters while maintaining an air gap between the film and the roofing material.

Roofing pie is a multilayer structure that provides reliable protection from various unfavorable factors

Attics Cladding the walls of the attic: algorithm of work and choice of material

A house with an attic is not just additional living space, but also a presentable appearance of the entire structure. Even if the room under the roof is not heated and is used only in the summer, it still has a powerful “air cushion” that helps retain heat inside the entire building.

Making an attic on your own will be difficult, especially if you do not have the relevant experience, because it is a fairly massive and complex structure.

The attic space can be installed under various types roofs, but the most popular is a broken or gable design. According to their structure, they are slightly different from each other.

In order to decide which design will be more suitable for your home and will be easier to install, you need to consider both options in more detail. In addition, the master who will be involved in the construction of the attic roof must figure out which of the two types of rafter system structures to choose.

Any roof belongs to one of the existing two types of rafter systems, it is layered and hanging design. Each of them has a different feature, and which one to choose depends on how the load-bearing walls of the structure are located.

Hanging structure

A hanging structure is a rafter system that rests only on the outer main walls. This happens when in the house itself, except for the external walls, there are no major partitions.

This design can only be used if between two capital walls a distance of no more than 8 m, since this system places a high load on the foundation. To reduce it, in hanging system different elements are used, such as tightening and headstocks, struts and crossbars. For example, the headstock hangs the tie to the ridge connection, and the struts pull the beams to the rafters.

For floor beams in a hanging system, hewn logs or fairly thick bars installed on an edge are used. Their cross-section must be at least 100x200 mm. The floor in the attic should be as reliable as possible, and in order not to make mistakes in the parameters, it is better to entrust the calculations to a specialist.

Layered system

The layered system, unlike the hanging one, is supported not just by two external load-bearing walls, but also by permanent partitions installed on the foundation. Therefore, when planning the construction of an attic, you need to think in advance what the structure will be like. strip foundation, on which permanent partitions will be installed. The layered system is perfect for installing an attic because it can withstand high loads compared to the hanging version. It provides good foundation for floor beams and, accordingly, for the attic floor.

If you make a broken version of the attic roof, then it makes sense to use a combined roofing system, that is, the side rafters are installed in a layered manner, and the ridge rafters are installed in the form of a hanging system.

DIY mansard roof: video, photo

When building a house from blocks or bricks with an attic, its front side is often built from the same material. This is convenient because you don’t have to calculate the parameters of these roof elements and assemble them from bars to lift onto the wall. But it is important to understand that the walls of the building must be on a reliable foundation and have good thickness, since such a pediment puts a significant load on the main structure.

If the attic serves as another floor year-round, then a gable wall made of foam blocks or bricks is an excellent option for creating a living space under the roof.

In order for attic rooms with a gable roof to be spacious and have a normal height, the angle of the roof slopes should be approximately 45-50°, depending on the width of the end part of the structure. If you take a smaller angle, the volume of the room will significantly decrease. Increasing the steepness of the slopes will make the roof unreasonably high, it will become heavier, will have greater windage under wind loads, and the cost of materials will be inappropriate.

Of course, installation gable roof simpler compared to a broken structure, since straight rafters are used without additional connections or any kinks. But the broken design allows you to make the room in this part more spacious, and the ceilings correspondingly higher.

The broken system is much more complex in design, calculations, and roofing, but it not only creates a more spacious space under the roof, but also gives solidity to the entire structure. Its main difficulty lies in the large number of complex connecting elements. All connections must be made in accordance with the technology, otherwise the roof will turn out to be unstable.

If the walls are built of brick or stone, then it is better to lay out the front parts in advance during the general laying. In this case, in order to create a unique rafter system, aligned with the finished gables, you can install intermediate rafters and special supporting fastenings to them.

Before purchasing and preparing material for a particular system, you need to draw up a design project with the appropriate dimensions - it will become the main guide for preparing and assembling elements during installation.

Video: rafter system for a sloping attic roof

Attic project

When developing a scheme for building an attic, it is better to do this in different projections in order to clearly understand how the elements of the rafter system will be placed. It is important to correctly calculate what the height of the roof ridge should be, since the size of the area depends on it.

When preparing a design diagram for constructing a roof for an attic, it is necessary to calculate the height of the ceiling, ridge and total area of ​​the room.

The minimum height from the floor to the ridge is 2.5-2.7 m, but if this distance is smaller, then the room cannot be called an attic; the name attic is more suitable for it. This indicator is established by SNIP standards.

In order for all elements to be accurately drawn and have correct location in the general system, it is necessary to start from a figure with right angles, namely from a square or rectangle - a cross-section of the attic space being created. Based on the width and height of the future room, you will never be mistaken with the angles at which the roof slopes are located, with the location of the rafters, ridge and other supporting elements. Having found out these parameters, they must be immediately entered into the drawing.

First of all, you need to calculate the middle of the width of the front wall. Further from this point, the height of the ridge, the attic ceiling, the location of the walls (racks) and the size of the eaves overhang are determined.

Due to the fact that each of these structures has a certain number of connecting nodes with different configurations, it would be nice to draw each of these connections separately in order to understand in detail the features of the pairing of all the elements that are connected at this point.

All rafter systems include basic and additional elements, which may not be found in every structure. The main components of the attic roof include:

• floor beams (the basis for the remaining elements of the system). They are laid on main walls.

• A rafter leg consisting of two sections (in the case of a broken pattern) or straight in a gable system. The top rafter in this case is called the ridge rafter, since it forms the highest point of the roof - the ridge, and the rafters that form the walls of the attic are called side rafters.

• Mauerlat is a powerful beam that is attached to the main side walls. It is necessary to install rafter legs on this element.

• A ridge board or beam is an integral element for a gable roof, but is not always used when installing a broken roof.

• Constructions - supporting elements that are required to strengthen the broken line and gable design. In the first case, the side and ridge rafters are attached to it, and in the latter, the stand acts as a good support for a long rafter. Moreover, the racks are the frame for covering and insulating the attic walls.

• Diagonal connecting elements additionally fasten the longitudinal beams or posts and rafters, thereby making the structure even more durable.

• Inter-rafter purlins are installed in the case of a broken roof for structural rigidity.

• Attic floor beams are used in both versions of the system - they connect the racks with them, and they act as a frame for the ceiling.

In order to be sure that the project is developed without errors, it would be a good idea to show it to a specialist. It will determine how correctly you selected the attic parameters to the length and width of the walls of the building.

Video: calculating a mansard roof using software

Material parameters for the construction of an attic roof

When the graphic element is ready, then, based on the dimensions set on it, you will be able to calculate the amount of materials that will be needed for the construction of the attic roof. It is necessary to select materials according to their characteristics, which must meet environmental and fire safety requirements.

For wood, it is necessary to provide an antiseptic treatment, which will significantly reduce the flammability of the materials. For construction you will need:

• boards for rafter legs, the cross-section of which is selected based on the results of calculations, which you will learn about a little below.

• Beam of 150x200 or 100x150 mm - for floor beams, depending on the width between load-bearing walls, rafter system, as well as for purlins, valleys or diagonal legs - if, of course, they are provided for by the design.

• Beam from 100x150 or 150x150 mm, intended for laying the Mauerlat.

• Typically, timber 150x150 or 100x100 mm is used for racks.

• Unedged board for the subfloor, as well as some fasteners.

• Annealed steel wire with a diameter of 3-4 mm - for fastening some parts.

• Bolts, nails, staples various sizes, corners of different configurations and other fasteners.

• Lumber for counter battens and sheathing for roofing material - depending on the type of roof.

• Vapor barrier and waterproofing membranes.

• Insulation materials intended for roof thermal insulation.

• Roofing material and special fasteners.

Rafter section

The rafters provide a roofing element that accepts the main external loads, which means special requirements are imposed on their cross-section.

The size of the required lumber depends on many parameters - from the step between the rafter legs, the length of these legs between the support points and ending with the wind and snow load that falls on them.

The geometric parameters of the rafter system are easily determined in the drawing. But to understand other parameters, you will have to turn to reference materials and do some calculations.

It's no secret that snow load differs in different regions of our country. Below in the figure you will see a map on which all of Russia is divided into zones demonstrating the snow load.

In total, 8 zones are distinguished (the last one is considered extreme and can not be considered for the construction of an attic roof).

Sg is an indicator in the table (carefully study the map and the table attached to it).

μ is a correction factor that depends on the steepness of the roof slope.

For example, if the roof slope angle is less than 25°, then - μ=1.0; if from 25 to 60°, then μ=0.7; if it is more than 60°, then the snow will not linger on the roof, and the snow load is not taken into account.

If the attic roof is of a broken structure, then for its different sections the load may have different values.

The angle of inclination of the roof can be determined by a simple ratio of the height and base of the triangle (usually half the width of the span) or using a protractor according to the drawing.

This indicator also largely depends on the region where the structure was built, on the height of its roof and on the characteristics of the environment.

And again, for the calculation you will need to determine the initial data from the map and the table attached to it.

The calculation for this task will be carried out using the following formula:

Wp = W × k × c

W – value in the table, depending on the specific region.

k – coefficient taking into account the location and height of the building (see table).

The letters in the table indicate the following zones:

• A - open areas, forest-steppes, steppes, tundra, deserts, forest-tundra, sea coasts, reservoirs and large lakes.
• B – urban areas, areas with frequent wind obstacles, artificial or relief, at least 10 m high, wooded areas.
• B – dense urban development, building heights from 25 m.

With– a coefficient that depends on the prevailing wind direction (wind rose of the region), as well as on the angle of inclination of the roof.

With this coefficient, the matter is much more complicated, since the wind can have a dual effect on roofs. So, it has an overturning, direct effect on the roof slopes. However, at small angles, the aerodynamic effect of the wind is of particular importance - it raises the slope plane due to the resulting lift forces.

As you have already noticed, the diagrams that accompany the tables indicate the areas of the roof that are subject to maximum wind loads, and also indicate the corresponding coefficients used for the calculation.

It is worth noting that at slope angles up to 30° (in the area of ​​ridge rafters), the coefficients are indicated both negative (directed upward) and with a plus sign. They somewhat dampen the wind load, and in order to reduce the impact of lifting forces, you need to carefully secure the roofing material and rafter system in this area, using additional connections (for example, annealed steel wire).

Once the snow and wind loads have been calculated, they can be summed and taken into account design features system, identify the cross-section of the rafter boards.

Please note that these data are indicated for the most commonly used coniferous materials (spruce, pine, larch or cedar). In the table you can see maximum length rafters between the supports, the section of the board depending on the pitch between the rafters and the grade of the material.

The total load value is indicated in Kilopascals (kPa). Converting this value into the usual kilograms per m2 will not be difficult. 1 kPa ≈ 100 kg/m².

As for the dimensions of the board along its cross-section, it is rounded up standard sizes lumber.

What tools will you need to install an attic roof with your own hands?

Of course, during work you cannot do without a set of tools, the list of which includes:

• screwdriver, electric drill;
• building level, tape measure, plumb line and square;
• chisel, axe, hammer, chisel;
• jigsaw, a circular saw, hacksaw;
• carpenter's knife

If the work takes place surrounded by competent mentors, step by step and carefully, and the tools are of high quality, the process will be much faster.

Do-it-yourself mansard roof: main steps + video

It is important to strictly follow the sequence of work, because this is the only way the structure will be strong and reliable.

1. Mauerlat fastening.

The installation of any rafter system should begin with attaching a powerful support beam - Mauerlat - to the end of the side walls of the buildings. It is convenient to install rafter legs on it. It is made from high-quality timber 100x150 mm. The Mauerlat is laid on roofing felt waterproofing laid along the upper end of the wall (regardless of the material).

Thanks to the Mauerlat, the load is evenly distributed across the walls and transferred to the foundation. It is fixed to the wall using metal studs, which are previously embedded in a crown or concrete belt running along the upper edge of the wall of the structure or with 12 mm anchor bolts. They must go into the wall at least 150-170 mm. If the Mauerlat is installed on a wall made of wood, then the beams are attached to it using wooden dowels.

1. Installation of the rafter system.

Installation of the rafter structure begins with the installation of floor beams, which can be mounted on top of the mauerlat (if you plan to move the beams outside the room, increasing its area). In this design, the rafter legs are fixed directly to the floor beams.

Otherwise, they can be laid on waterproofed walls and secured with brackets or corners to the inner edge of the Mauerlat. This option is used if the rafter legs need to be fixed directly to the mauerlat.

The posts should be at the same distance from the middle of the floor beam. In the future, they will determine the location of the walls of the room, namely its width.

The bars for the racks must have a cross-section corresponding to the size of the floor beams. The posts are attached to the beams using wooden overlays and special corners. But first, they are baited with nails, after which they are leveled using a plumb line and building level and only then are they thoroughly secured with the expectation of upcoming loads.

As soon as the first pair of racks is installed, they are fastened on top with a block (tightening). It, in turn, is connected using metal corners to the racks.

When the tie is secured, you will have a U-shaped structure. On the sides, layered rafters are installed on it, which are laid on the mauerlat or attached to the floor beam with the second end.

On installed supports a groove (special notch) is cut out for timber or rafters. With its use, the rafters are installed on the mauerlat beam and secured with metal brackets.

To ensure structural rigidity, struts can be installed from the base of the rack to the middle of the side rafters. If this turns out to be not enough, and you do not mind the material, then it would be a good idea to strengthen the overall structure with contractions and additional racks.

Then the middle is calculated on the puff. A beam will be attached to this place, which will support the ridge connection of the upper hanging rafter subsystem.

The next stage is the installation of ridge rafters. They can be fastened with various connections - these can be powerful bolts with metal washers or plates, or a metal plate.

After installing them, the headstock is attached to the middle of the tightening and the ridge.

Upon completion of work on one part of the truss structure, it is necessary to do the rest according to the same principle. The distance between adjacent rafters in such a system should be no more than 900-950 mm, but the best option there will be an interval of 600 mm, which will give the structure the necessary stability and rigidity and will be convenient for insulation using standard mats mineral wool. But this significantly makes the structure heavier and increases the cost of materials.

First, the side parts of the system assembly are installed, then the intermediate parts. They are connected to each other by purlins, which are installed between the upper ends of the racks and work like spacers. So, we get a rigid structure of the attic rafters, where there will already be finished frame for wall decoration.

Waterproofing attic roof

As soon as you have built the rafter system, you can begin finishing it with insulation and other related materials.

It is worth noting that the first coating on top of the rafters should be a waterproofing and windproof film. It is attached to the rafters using a stapler and staples, starting from the cornice. The canvases are laid with an overlap (200 mm), and then the joints are glued together with waterproof tape.

A counter-lattice is placed on top of the waterproofing, which will better fix the film on the surface and create a ventilation distance between the roofing and windproof material. Typically, the counter-lattice is made of boards 50-70 mm thick and 100-150 mm wide.

A sheathing is fixed perpendicular to it, on which the roofing material is laid. As for the pitch between the slats, it is calculated depending on the size and type of sheet roofing material, taking into account the overlap required for it.

If you use soft roof, then plywood sheets are usually fixed to the counter-lattice.

How the roof covering is installed

The roofing material is fixed to the prepared plywood or sheathing. Typically, its installation begins from the roof eaves and then one by one, from one of the edges - depending on the type of roof. Sami roofing sheets are installed overlapped. If metal tiles or metallic profile, then this material is secured using special self-tapping screws with elastic gaskets. Typically, fasteners are matched to the color of the material.

The most difficult stage in covering a sloping roof is the transition from layered side rafters to ridge rafters. Some difficulties may also arise if the roof has projections for arranging the roof above windows or balconies.

Moreover, if a chimney pipe goes onto the roof, it requires a separate design of the hole in the insulating layer and rafter system, and on the roof - a device around reliable waterproofing. It is worth noting that the work of constructing any roof, including such a complex one as an attic roof, is very important and dangerous, and therefore requires increased safety measures. If you do not have experience in such construction processes, then it is better to entrust their implementation to specialists or invite experienced craftsman, under whose supervision perform all actions carefully and carefully.