What boards to use for the rafters of the attic roof. Broken mansard roof with your own hands. Installation of support posts and purlins

If you have made such a decision on how to build an attic, it will be correct. Before building an attic in an existing house, you first need to decide on its shape, and so whether the roof will be completely redone into an attic floor or not.
After all, the construction of an attic is considered not only more economical, but also a process that will require much less labor in comparison with the construction of the next floor. It is these facts that make the construction of the attic very popular. Projects of country houses with an attic, as a rule, have a special or, as the builders call, "broken" roof, since it makes it possible to maximize the usable area.

Particular attention in solving such a question as to build an attic must be paid to the quality of the roof. Since it must have not only an aesthetic appearance, but also have excellent thermal insulation, as well as have good waterproofing. The best thermal insulation material for roofing is either slate or ceramic tiles, but in no case use metal tiles, as they tend to get very hot in the sun. In this case, how to build an attic with your own hands? At the initial stage of building construction, it is possible to make calculations of the supporting structure with maximum accuracy.

It should be borne in mind that the installation of rafters must be done at an angle (from 30 to 60 °), since an increase in the degree of inclination leads to a decrease in the usable area of ​​the attic.
To solve the problem, you can insulate the attic from the inside using mineral wool.

A residential attic space requires a large layer of insulation. The material must comply with fire safety requirements and not be toxic. Mineral wool is one of the most suitable options.

Varieties of material

The main types of mineral wool are basalt wool and glass wool. Each has its own properties, pros and cons.
Basalt wool

Basalt wool is produced from gabbro-basalt rock. Carbonate rocks are specially added to it, which makes it possible to regulate the acidity modulus. The material of higher acidity is more resistant to moisture and more durable. Adding binders to basalt wool: bituminous, synthetic, composite, bentonite clays - bonds the fibers together, helps to give the desired shape.

Glass wool

Glass wool is a mineral material for the manufacture of which raw materials used in the production of glass are used, as well as waste, broken glass.

The properties of glass wool are different from basalt, its thickness is 3–15 microns, and the length is several times longer than basalt. Therefore, glass wool slabs are more elastic, have greater strength, and are resistant to vibrations. Glass wool is fire resistant, withstands up to 450 ° C.

Despite all the advantages of glass wool, there is one significant drawback that reduces the popularity of its use. When laying this material, many small particles are formed that are harmful to health. Therefore, the installation is carried out in special clothing, footwear, and a protective mask. It will not work to clean them after work, you will need to throw them away.

Isolation nuances

When insulating the roof, it is better to use cellulose wool, it provides better moisture conductivity, does not allow humid air to accumulate under the roof.

The main difficulties of insulation are manifested when working on roof slopes with a rafter structure.

Here it is necessary to use dense cotton wool, which can be securely placed between the rafters. It should be light and firm.

The main advantages of mineral wool are its incombustibility, soundproofing, good thermal insulation performance, vapor permeability, high environmental friendliness, and a relatively affordable price. It is produced in plates, mats, cylinders, there are options with foil coating.

If the size of the insulation is greater than the distance between the rafters, it is cut into the necessary pieces, adding a few centimeters for a tight fit.

This method is well suited for insulating attics, living quarters located directly under the roof. The disadvantage can be considered a decrease in internal dimensions due to a layer of cotton wool, drywall and additional finishing.

Thermal insulation methods

Depending on which element of the building structure is insulated, there are 2 ways to insulate the roof from the inside.

Floor insulation

The first option is floor insulation. The method is inexpensive, very simple to implement. It consists in laying cotton wool on concrete base slabs or, in the case of a wooden floor, between structural elements. Any kind of mineral wool will do, even soft and granular. Installation is simple, you do not need to bypass the rafters, as when insulating the roof slopes, you can easily fill in all the gaps and cracks.

Thermal protection of skates

The second option is to insulate the roof slopes. If the premises in the attic are not used, then this option is economically unprofitable. The consumption of materials increases significantly, it takes more time due to the bypass of the rafters and additional fastening of the mineral wool.

Thermal insulation of slopes can be done in two ways: over open rafters or between them. In the first version, wooden beams remain visible inside the room and have an additional decorative function.

Sequence of work

Regardless of which method of insulation with mineral wool is used, the general algorithm of actions is as follows: surface preparation, waterproofing, installation of insulation, laying of vapor barrier, cladding.

Preparatory activities

Before starting work on thermal insulation, the surface to be insulated must be prepared. The structure is inspected, if necessary, the identified defects are eliminated, cleaned of dirt and debris. The preparatory work can also include the calculation of the amount of material.

The thickness of the insulating layer should be at least 15–20 cm, therefore, when choosing cotton of a lesser thickness, it will need to be laid in two layers.

Waterproofing

To protect the roof from moisture, waterproofing is installed on the surface to be insulated. It is laid with an overlap, securing with a stapler and gluing the joints with tape.

It is important to install the waterproofing membrane so that there is a ventilation gap between it and the insulation, and the material completely covers the entire rafter system and goes slightly onto the walls.

Then, on top of the insulation, a batten of slats is nailed to the rafters, which will secure the material and provide a ventilation gap. All wooden structural elements are best treated with a special antiseptic.

Insulation laying

After installing the waterproofing, you can start installing the insulation. To do this, the mineral wool is cut into pieces about 5 cm wider than the distance between the rafter beams. Then, after laying, the material will straighten out and fill the space better. The installation of mineral wool should be carried out in such a way that the material fits as tightly as possible to the beams and there are no gaps.

Arrangement of vapor barrier

After laying the insulation, it is necessary to protect it from water vapor coming from inside the room. If this is not done, the mineral wool will gradually get wet and lose its thermal insulation properties. Therefore, a vapor barrier is installed on top of the insulation. As a vapor barrier, special foil materials, polyethylene films or roofing material are used.

For tightness, the vapor barrier is laid with overlapping layers, the seams are glued. It is important to install foil vapor barriers with the metallized side inside the attic. The structure is fixed with wooden slats, on which the sheathing (lining or drywall) is subsequently attached.

Roof insulation with mineral wool is one of the most affordable ways to equip a warm and cozy attic. The main thing is to strictly observe the technology. And then everything will work out.

Try to pay special attention to the insulation of the attic roof. If the roof is not insulated, do not expect warmth in the attic. A roof is a roof covering. A mansard roof is a "roofing pie" consisting of several layers: a vapor barrier from the inside, a waterproofing layer from the outside, a heater between them and an air gap.

Various materials are used as insulation. The characteristics of the materials used depend on several factors: the functional purpose of the room, the level of humidity, critical temperatures, loads, and so on. Non-flammable, basalt materials are the best option.

Various materials are used as insulation for the attic from the inside. The most popular and simple is mineral wool

It is not recommended to use polyfoam. It is flammable. Poor vapor permeability. Mineral wool is perfect. It is pressed into a plate. On the inside, there is a vapor barrier layer. On the outside - waterproofing (special layer).

Now the use of spraying polyurethane foam for insulation of the attic from the inside has become quite popular. This method is also quite economical and very effective.

If the attic is made from an old attic, then, as a rule, the rafters are preserved. The load is minimized by using low-density insulation for this, since they are much lighter. The disadvantage is that they are blown by the wind. Additionally, a windproof, vapor-permeable material is laid.

Approach the installation of insulation with due attention. Do not forget that there is sufficient ventilation space between the roof covering and the insulation layer.

The attic is warm in winter and cool in summer only when all the work on the walls and roof insulation is done correctly. Do not ignore these rules and your budget will have a tangible effect.

The attic is a trendy architectural element. F. Mansara (French architect) three centuries ago was the first to use the attic space not only for economic purposes, but also for housing.

Now in civil and industrial construction, it is quite widely in demand. In individual construction, the attic is experiencing a real boom. It is equipped both during the construction of a new house and during the repair of attic rooms (roofs).

The house takes on an expressive look, and the attic space is used functionally and efficiently. The area occupied by the attic is decent. Additional room for a good recreation room (billiard room) or a wonderful summer bedroom. By making it warm and dry, it will be habitable.

A well-insulated and well-made attic can be an excellent rest and work room.

How to properly insulate the attic from the inside? A project developed in advance is required. It will allow you to prepare well, provide for all the nuances. A competent approach to attic insulation and the mandatory use of high-quality materials will help to avoid mistakes that can play a very bad role over time.

In a private house, as a rule, large heat losses are observed. Basically, this happens through the ceiling and overhead floors. The processes of wetting (drying) of the insulation under the roof worsen its quality. A violation of the microclimate is often the cause of cold inside the house. This occurs mainly due to poor quality construction work associated with the attic.

It is recommended to insulate the attic not only from the outside, but also from the inside. Warming is a technically rather complicated process. The impressive area of ​​the attic floor, its maximum contact with the external environment, the complexity of the structure - requires certain knowledge and skills from the one who will be engaged in its insulation.

Mansard structures are distinguished by the fact that they can be constructed from a wide variety of materials, for example, from wood, metal, reinforced concrete. There are no restrictions here, it is only necessary to ensure stability and proper insulation. Indoor ceilings can also be very different: inclined, flat with one inclined wall, formed by two slopes, converging at an acute angle. All this and much more has contributed to the popularity of the attic for more than four hundred years.

The main advantages of such a roof are as follows:

1. Possibility of an attic superstructure, that is, the use of the infrastructure of an already standing building. At the same time, there is no need to completely disassemble the entire roof, which allows significant savings during work. This is an additional floor that can be used for its intended purpose.

2. The living area of ​​the house is increased due to the reconstruction of an unused attic space. This allows you to add a full-fledged second floor at a relatively low cost.

3. In places with rather dense buildings, the attic second floor is the best way out.

4. The external appearance of the building is improving, the building acquires a complete, holistic appearance.

5. Attic can be built on not only one level. If necessary and observing all the rules and requirements, it is possible to build a two-tier attic, which will decorate any building, adding additional living space to it.

6. When constructing an attic, heat loss through the roof of the house is much reduced. It also translates into lower heating costs during the winter months.

7. Construction of attics is possible even in a residential building without the need to move out residents. For this, it is not necessary to use heavy construction equipment, all work is carried out directly on the roof of the building in the shortest possible time. A new floor can be built with virtually no problems and costs.

But when building an attic, there are also disadvantages, like any design. It is worth noting such disadvantages as:

1. When arranging such a room, a certain part of the usable area is lost.

2. Beveled and sloped ceilings greatly reduce the height of the walls, ceilings in attics are usually low, not exceeding 2.4 meters.

3. Windows in many cases can be located only in the ceiling, which is not always convenient.

4. Rafter structures begin to degrade quickly due to lack of ventilation. Typically, their service life is about three times less than with a cold attic.

5. In winter, skylights often accumulate large masses of snow, which reduces the level of already insufficient lighting.
Varieties of designs

When deciding how to make an attic, you must first decide what type of rafter system will be used. A characteristic feature of the attic structure is its broken, rather steep configurations, but we must not forget that this is not an aesthetic function, but a purely practical one. Such broken shapes provide:

· Correct transfer of all loads to the bearing walls;

· Allow you to effectively protect the entire structure from precipitation;

· Give stability to such negative phenomena as temperature sharp drops, showers, snowfall, the formation of a large amount of ice.

The simplest form of a residential attic is a triangle, the most complex is with a break. All horizontal logs and vertical posts are recommended to be made of thin wooden beams.

Among the truss systems used for the attic floor, the most commonly used are:

1. Hanging type rafters. They rest on the walls, creating a horizontal load. If you decide to make an attic second floor using this type of rafter system, then you need to take into account the design features. To connect the beams, intermediate supports are not used here, only special puffs made of metal or wood.

2. An inclined type of rafter system is recommended for small cottages where the load-bearing wall is located in the center or there are intermediate supports. The rafters rest on the outer walls, the middle part of the structure on the inner wall. Such a simple system can only be used for those houses in which the distance between free-standing load-bearing walls is no more than six and a half meters.

3. Hanging and inclined rafters can be in the form of right-angled triangles, which have a stop behind the load-bearing wall. In this case, the Mauerlat does not need to be erected, ordinary beams are taken for the rafters. Strut braces are required, all racks cut into the floor beams, the rafters are fastened with anchors.
Construction stages

So how to properly assemble the attic structure? The sequence of all work should be strictly observed, which will allow you to build a solid, reliable attic. It is imperative to correctly identify all loads, which can only be done by experienced designers.

The construction of the attic provides for such work as:

1. Dismantling the old roof. In this case, it is not required to completely disassemble the overlap. Unless it is provided for by the project.

2. If necessary, the floor structures are reinforced. This is done so that the second floor (attic) does not give unnecessary stress. If necessary, an additional layer of waterproofing is laid at this stage.

3. Construction of the truss system, insulation of the attic itself.

4. Installation of windows.

5. Internal and external finishing of the building.

For the construction of the attic, it is recommended to use wooden beams that have a cross section of fifty to one hundred and fifty centimeters. At the same time, the following sequence of work is observed: first, the frame of the future structure is made, after which the support beams and rafters are strengthened. After the installation of the stepped bevels, waterproofing work, insulation is laid. Now you can reinforce the battens and install the roofing material. Finishing work is carried out last, after all windows have been installed.

The attic second floor must be insulated in order to ensure the safety of the structure and the comfort of living conditions. For such a process to become effective, it is necessary to observe the construction of a multi-layer "pie", which includes:

· Internal finishing material on the ceiling of the attic room: moisture-resistant plywood, drywall, etc.
· Vapor barrier membrane;

· Insulation (usually it is mineral wool in rolls or slabs);

· Laying of waterproofing;

· Installation of roofing (tiles, corrugated board, etc.).

The layer of insulation should be two hundred and fifty to three hundred millimeters, often a special frame is made for laying it, attached perpendicular to the rafter system. When laying, it should not be allowed that gaps and cavities remain between the insulation plates, as this will lead to significant heat loss, low thermal insulation efficiency.

The attic is not only beautiful, but also a very functional architectural element that is able to fulfill the numerous tasks assigned to it. This is a great place to live. Here you can equip a nursery, a playroom or a large gym.

Attic construction technology consists in high-quality and consistent performance of such works:

1. Development of a project for the construction of an attic floor or its re-equipment.

2. Dismantling of old roof structures.

3. Strengthening the wall structures of the upper floor.

4. Installation of waterproofing and thermal insulation of ceilings.

5. Construction of the end walls of the attic room.

6. Construction of a mansard roof, its insulation and decoration.

7. Installation of attic windows.

8. Arrangement of a new living quarters.

For work, you will need to purchase materials and tools. It is usually necessary to have wall panels (or other material) for sheathing the end walls of the attic, thermal insulation materials for walls and pitched roofs, roofing materials, roof beams, finishing materials, etc.

After preparing everything that is required for construction, project development, you can begin the main work. First you need to make a frame for the roof. Rafters can be made of beams 50x150 cm in size. The structure must be well fixed, slings, support blocks installed, attic walls to be erected and rafters installed. The rafter structure must be installed securely and accurately. After that, stepped bevels of the walls, partitions of the attic room are installed, and work is carried out on insulation and waterproofing of the attic. Next, you should build a crate for the roof of the attic, lay a heat insulator on it, strengthen it and then finish the roof with roofing material. After that, the installation of doors and windows, interior decoration and arrangement of the premises is carried out.

Attic roof

In order to understand how to make a roof in the attic correctly, knowledge about the features of such a room will not be superfluous. Roof leaks and other roofing defects will negatively affect the entire building to a much greater extent than the same defects of a conventional attic roof. In this case, water will flow into the living room, which, most likely, will lead to the repair of the premises.

The main feature of a mansard roof is that it is exposed to moisture both from the outside and from above (snow, rain, etc.) and from below (the formation of condensation from the moisture in the air of the living quarters of the lower floors). To eliminate this problem, the attic construction technology provides for the device of a special vapor barrier layer, which prevents the penetration of moist and warm air from living rooms to the tiles.

It is also necessary to make waterproofing under the roofing material and ensure sufficient ventilation of the roof of the attic space. Soft bituminous shingles or metal shingles can be used as roofing.

Warming and arrangement of the attic

Due to the fact that the attic is usually used as a living space, great importance is attached to the device of its thermal insulation. High-quality insulation of the attic roof ensures the creation of a comfortable microclimate in such a room and other rooms of the house, effective heat preservation and a long service life of the entire building. There are several ways to insulate the attic. Insulation outside implies general insulation of the entire house.

The optimal and most effective way is additional internal insulation, involving the use of a multi-layer heat-insulating structure, consisting of the following layers:

First layer (inner) - finishing material, for example, sheets of plasterboard, plywood and other materials that form the ceiling of the attic room

The second layer is a vapor barrier film

The third layer is a porous heat-insulating material (mineral wool, etc.)

The fourth layer is a waterproofing material, laid with the formation of a small gap and the possibility of a simple drainage of water to the outside

· The fifth layer - roofing (metal, soft roof, etc.).

Advice from the master!

In addition to insulating the attic roof, it is also necessary to insulate its walls and floor. Arrangement of premises in the attic includes the implementation of such works as the installation of dormers, internal partitions, doors, as well as decorative finishing.

Installing pitched roof windows is the best solution for an attic. Glazing can occupy a significant surface area of ​​the attic, at least 12.5%. The glasses used in such windows are special: they do not break with strong pressure or impact, but crumble into granules that do not have sharp and cutting surfaces.

The specificity of the attic space allows you to equip them in a special way, to arrange them in an unusual and original way. Many designers recommend using translucent plastic partitions or partitions decorated with translucent fabrics for zoning these rooms. When choosing a shade for wall decoration, it is recommended to give preference to light tones that will make the interior light and pleasant. It is not recommended to decorate skylights with curtains, but it is better to choose light-colored blinds.

Having learned how to build an attic yourself, equip it, create a comfortable, cozy and unusual room, you can try to build an upper floor at home. This is a great way to make your home unique and individual, to increase its usable area and equip additional living space.

After the overlap is reinforced, you need to decide on the size of the attic rooms, their height at the walls should not be lower than 1.5 m, and in the middle part there should be a standard height of 2.5 m, or even more. After that, a guide profile (PN) is attached to the floor, for drywall, and above it, the same profile to the rafters. Marking, which is done using a plumb line, tape measure, or a strong cord. Then, the profile of the racks (PS) is installed in the guide profiles, the step of which should be 600 mm. On inclined ceiling surfaces, the metal profile can be mounted horizontally. After that, when the location of the rooms is clearly visible, several dormers can be installed on the roof so that the rooms are well lit with natural light. In addition, it will be necessary to make an opening in the ceiling for the construction of a staircase to the attic. The least space on the ground floor will be occupied by a single-flight staircase with "goose step" steps.

The popularity of sloping roofs is due to the economy of construction and the ability to rationally use the attic space. They are used to organize insulated and non-insulated attics. The technology for the construction of roof structures with a variable angle of inclination of the slopes differs from the traditional two-slope scheme.

Therefore, those who want to acquire an attic floor and successfully prove themselves in the field of a roofer need to know how the rafter system of a sloping roof is arranged and how the sizes of materials for its construction are calculated.

The most striking and expressive representative of the class of sloping roofs is a pentagonal structure with a clear difference in the angles of inclination of the slopes. Even without delving into the specifics of its structure, one can understand that it is built of two tiers piled on top of each other. In the lower solid tier there is an attic, which gave the second name to the sloping roofs. A less voluminous tier-top, crowning the lower part, determines the shape of the structure in the area of ​​the ridge.

Briefly about the specifics of the rafter structure

The rafter frame for both parts of the attic roof is built according to the rules dictated by the usual one. The lower part of the sloping roof frame is built by installing layered rafter legs. In the device of the upper part, both layered and hanging rafters can be used. The bottom of the layered rafters has the right to rest on the Mauerlat or on the floor beams. The support for the top is most often a wooden frame, which at the same time plays the role of a frame for one of the walls of the attic. In the device of the upper tier, they are guided mainly by the convenience of work for the performer.

Traditionally, the angle of inclination of the slopes of the lower part of the sloping roof is much steeper than the upper one. It is they who create a kink - a clear indicator of the use of broken technology in the construction of a roof. However, the steepness of the upper and lower parts of the slopes can be equal, which is why the broken structure will look like a regular gable. But they stand it using the standard method for sloping roofs, because the frame of the lower tier is obliged to provide the possibility of organizing the exploited space. Those. the rafter system must have the necessary elements with a given bearing capacity for the walls and ceiling of an insulated or cold attic.

Types of loads and their combination

The sophisticated formulas according to which the rafter system of the sloping roof is calculated by the designers of construction enterprises, we will not give. The builders know them even without us. Those who decide to build one or two roofs on a suburban area do not need such fundamental information at all. There are plenty of programs on the Internet that perform complex mathematical operations in a couple of seconds to calculate the cross-section of rafters, supports and beams. It is better to analyze what data will be required to be entered into the program, as well as what types of loads on the floor, rafters of the upper and lower tiers should be taken into account.

Download the program itself here -(only Excel is needed to work). Further we will give examples of working specifically with it.

Why do we need limits

Different types of loads will act on each element of the rafter system of a sloping roof. The sum of the loads should not lead to deformations and damage requiring mandatory repair. Bearing structures according to the rules are calculated taking into account two limit values, these are:

• Ultimate strength is a condition, exceeding which leads to the destruction of the building structure, to the loss of endurance or stability.
• Ultimate deformation is a condition, exceeding which leads to unacceptable deflections, as a result of which not only the geometry of the structure changes, but the nodal joints are violated.

For both types of these limit states, the designers make calculations. An independent roofer does not need these subtleties too much. In the calculation programs available on the Internet with the formulas embedded in them, the limits have already been taken into account. They are introduced into the calculation algorithm in the form of signal values ​​of the type:

• N tr. strength - the size of the element of the rafter system, a decrease in which will lead to a state of loss of strength.
• N tr. deflection - the size of the element, the reduction of which will entail a threatening deformation.

When referring to automatic computational help, close attention should be paid to such values. This is the minimum limit indicating that the actual design values ​​should be higher.

The list of loads acting on the roof includes the weight of winter precipitation, wind force, own weight, weight of furniture and people operating the attic. Loads can act simultaneously, alternately, or in any combination of the type of snow + furniture + people; snow + wind, etc. Calculations are carried out to the maximum in an effort to provide for the probability of exposure to the greatest load.

How to determine the weight of the snow cover

No special knowledge is needed to determine the weight of the snow cover. It is carried out by finding out the belonging of the construction site to a specific "snow region". We found a region on the map with the number assigned to it, then looked in the plate to see how much snow would press on a horizontal surface.

For the rafters of the upper and lower tiers of a sloping roof, the snow weight indicators will be different. Slopes of a sloping roof are in most cases unequal in terms of the angle of inclination. Solid sediments have more opportunity to linger and lie on the close to the gentle top than on the steep slopes of the lower part. It should be noted that on slopes with a steepness of up to 30º, the weight of snow is taken to be equal to one of the average statistical value adopted in the region on the basis of long-term observations of the meteorological service. It is believed that snow does not linger at all on slopes with a steepness of 60º and more; is zero. The value of the snow weight in the interval between the indicated slopes is found by interpolation. For example, if the angle of inclination is 45º, then the tabular indicator should be multiplied by a factor of 0.5, for 50º by 0.33, etc.

How to find wind load

Wind load is needed to calculate the stability of the rafter system. To determine it, we again use a zoning map, but already drawn up according to the values ​​of wind pressure. This indicator is necessary for the rafter legs of both tiers of the roof, because the gusty wind is able to disrupt and carry away the gently sloping part, and overturn the steep part. The wind strength information determined from the map is corrected by multiplying by a coefficient developed for different types of terrain.

In regions with a high wind load, the frequency of attaching the rafter legs to the walls increases, i.e. they are fastened with wire twists more often than one. For stability, the number of wind ties increases - struts, supports, boards or battens nailed to three or more rafters. Their weight must be taken into account when calculating the total weight of the roof structure.

Roof weight load

Roof weight is a prefabricated characteristic with individual parameters. In fact, this is a mass of a roofing cake of a specific insulated or cold structure with a certain type of coating and a continuous or sparse crate specially arranged for the coating. It is calculated per meter of roofing area.

The average values ​​for the weights of the coatings can be found on the plate. It should be noted that when using embossed roofing materials, the weight of the snow cover should be increased by 10%. For example, if corrugated board is produced with a large wave, it should be remembered that the snow cover in the recesses can accumulate and lie for a long time.

The weight of the battens depends on the type of coverage. The device of a soft roof requires continuous flooring from boards, sheets of moisture-resistant plywood or OSB boards. Profiled sheet metal, slate, clay tiles are mounted on bars installed with a certain pitch. The weight of the battens will be increased by installing diagonal bracing in regions with high wind loads. The weight of the insulation and the rafter system itself with struts, supports, girders and other elements is also calculated on an individual basis.

For preliminary calculations, there are approximate average indicators:

• the weight of the wooden lathing is from 10 to 12 kg / m²;
• weight of layered rafter legs with a run from 5 to 10 kg / m²;
• the weight of the hanging legs of the truss truss is from 10 to 15 kg / m².

The readings calculated by the programs should not deviate too much from the figures shown. For insulated attics, the list of loads should be replenished with the weight of the sheathing. In the case of using a heater with a coefficient of thermal conductivity slightly different from 0.04 W / m × ° C, its mass may be neglected.

We have shown where and how to find values ​​to enter into calculation systems. All other information for the mathematical determination of the cross-section of rafter legs, beams, supports is entered according to the design data. If the design system warns that "the condition is not met" or the bearing capacity is not provided, the dimensions of the elements should be increased.

Construction of a broken rafter system

Before proceeding with the construction of the rafter system for the future sloping roof, it is necessary to make a project and calculate the structural elements. We will assume that the design stage has been passed.

Consider one of the typical examples of the construction of an attic with two tiers of layered rafters erected above a brick box. We will fix the rafter system to the Mauerlat - a wooden frame made of 150 × 200mm timber, laid flush with the inner perimeter of the walls. A row of bricks was laid along the outer edge of the box, masking the Mauerlat and removing part of the spacer load. The upper plane of the Mauerlat should be 2-3 cm higher than the brick strapping.

Installation of floor beams

We begin the construction of the floor by installing the extreme beams, the outriggers of which determine the width of the eaves. Next, along the lace stretched between the extreme beams, we install intermediate elements with a step equal to the distance between the rafter legs. For insulated roofs, it is recommended to make the step equal to the width of the thermal insulation plate so that the insulation would sit tightly in the inter-rafter space intended for it. For non-insulated structures, the step is calculated so that a whole number of rafter trusses with the same distances between them fit.

The size of the beam for the construction of the floor is 100 × 200mm. When laying the beams, we align their upper plane, if it is impossible to set it strictly to the horizon. Alignment is carried out by trimming the Mauerlat or lining of chips under the beam. After attaching the beams to the Mauerlat, we attach a short beam to their end, so that they form a plane for the end eaves overhangs. The spacing between the short beams doesn't matter, maybe 1m or so.

Construction of attic walls

We mark on the arranged overlap the lines of the location of the row of supports for the rafter legs of the lower tier. Simultaneously with the supporting function, they play the role of a frame for the walls of the attic.

We act as follows:

• We install corner supports, for the manufacture of which we use a beam of 100 × 150 mm with a length of 10 cm more than the final height of the attic ceiling. We verify the verticality of the supports with a plumb line, we will fix it only after we are convinced of the perfection of the installation. For stability, we fix their position with temporary braces. By analogy, we mount the supports in the middle of the pediment walls.
• We connect the corner supports with a cord to indicate the location of the intermediate struts. For the manufacture of intermediate supports, a material of 50 × 150 mm with an equal height of the corner supports is suitable.
• On top of two rows of supports, we lay girders made of 50 × 150mm board. Temporary spacers are no longer needed, the constructed walls of the future attic are stable even without them.
• We install a board on the girders with an edge, it will form the ceiling of the attic.
• On top of the ceiling of the attic under construction, we lay a board 25 × 150mm. It does not need to be installed along the axis of the building. It is better to lay parallel, departing from the axis 20-30cm.

The result of the efforts made is a ready-made attic frame and supports for installing the upper tier of rafter legs.

Installation of rafters of the lower tier

The rafters of the lower tier of a sloping roof are made and installed using the standard layered method:

• We apply a board of 25 × 150 mm of the required length to the end of the structure being constructed and, in fact, mark the lines of the upper and lower cut with a pencil. This is a template that can be used to make all the rafters of the lower tier, if there are no deviations in the geometry of the rafter system.
• If there are doubts about the perfection of the previous work, we install only the extreme legs and pull the lace between them. According to the template on the remaining rafters, we make only the upper cut. We will mark the lower line in fact, aligning the upper plane of the workpiece with the cord guide.
• We install the rafter legs. We fasten them to the floor beams with brackets or metal corners, and at the top to the girders with two or three nails.

It happens that one board is not enough to cover the lower slope along its entire length. In such situations, the rafters are mounted from two short boards, sewn with a cut of material of a similar section with a length of 1 m or more. True, it is still advisable to order lumber of the required length so as not to weaken the structure with stitched sections.

Installation of the rafter legs of the upper slopes

To make and install the upper rafters, you first need to mark the central axis. To do this, the trim of the inch should be nailed to the extreme ceiling board of the attic strictly vertically. One of the trimming edges must exactly coincide with the central axis of the rafter system of the sloping roof indicated on the diagram, then:

• We try on an inch to the end for the production of a template and mark on it the cutting lines, the upper of which we draw directly along the axis indicated by the trim.
• We make a pair of rafter legs of the upper slopes according to the template. If we do not doubt the geometry of the constructed frame, we make several blanks at once. Otherwise, we do the same as with the lower brothers.
• We install the first pair of rafters, calling for assistance from two pairs of working hands. You cannot cope with the installation alone, because they do not have an upper support. To prevent the newly erected truss from falling, we support it with a strut.
• We mount the rest of the roof trusses of the upper tier. We support them with struts every 3-4 pieces. The angle of inclination of the braces must be more than 45º. The direction of their inclination should be alternated.

Note that in order to prevent stretching and sagging of the attic ceiling boards, each upper truss must be equipped with a board suspension of approximately 25x150mm.

A photo selection will acquaint you with the specifics of the nodal connections of the rafter system of the roof of a broken type:

Sheathing of gables and construction of lathing

Along the line of the ridge and the fracture lines of the slopes, the crate is made solid, regardless of the designed type and the step of its installation. Across the direction of the rafter legs, two boards are nailed with a gap of 2-3mm between them. A similar continuous flooring is arranged in valleys, if any, around dormers and chimney openings. In the case of using soft varieties of roofing, the sheathing is arranged continuous over the entire area of ​​the slopes.

If the thickness of the insulation is equal to or greater than the width of the rafters, a counter-lattice is arranged in front of the crate, constructed by installing a distance bar. It is necessary to form a gap between the waterproofing and the roofing material. Nail the distance bar from the outside of the system to the edge of the rafter. If the thickness of the insulation boards allows you to leave the ventilation gap without remote tweaks, there is no need to install a distance bar. It is also not needed in the construction of a non-insulated roof.

Upon completion of work on the construction of the rafter system, cornices, pediment walls, called tongs in wooden housing construction, are sheathed. Short overhangs adjacent to the gable walls are equipped, after which it is time to lay the roofing.

Video selection for independent builders

Those who wish to visualize the process of constructing a sloping roof can be helped by three videos with step-by-step production of work:

It is impossible to consider within the framework of one article all the options for the construction of truss structures for sloping roofs. There are different types of roofs, architectural parameters, regions. There are many nuances used in specific construction conditions. However, the examples given by us perfectly demonstrate the general technological principle. This information about the calculation rules and construction schemes should help both home craftsmen and owners who control the work of the hired team. Leave your questions, if any, in the comments.

Absolutely everyone understands that the attic is, in principle, a converted attic. But this re-equipment has its own nuances, design solutions, as well as work with thermal insulation and roofing. In fact, building an attic with your own hands in a country house is almost no different from building any other roof. Anyway, let's take a closer look at this process.

So, to build an attic, you need to purchase:

• wooden beams, the cross-section of which is 50x180 centimeters for rafters (as for the length, everything will depend on the planned size of the building and what the slope of the slope will be);
• wooden boards for the lathing;
• material to carry out the cladding of the end walls, for example, wall panels;
• fasteners for the roof: nails, self-tapping screws, metal corners, metal profiles, in order to additionally strengthen individual structural elements;
• thermal insulation material;
• vapor barrier material;
• waterproofing material;
• roofing material;
• material for interior decoration of the attic.

So, the first step will be the task of strengthening the floors between the attic and the first floor. This is an obligatory work, since the load that will be carried out on the floor will increase significantly.

Once the overlap is reinforced, you need to tackle the rafter system. Do not forget that constant quality control of the connection of individual elements is necessary.

In the event that you will use a sloping roof, first of all, you will need to install the support beams and end walls, only after this has been done, you can start assembling the frame of the truss system. The fastening of individual elements of the frame is carried out using a "groove-protrusion" connection; to increase the strength, metal plates are used.

Do not forget that each wooden element needs preliminary treatment with a special compound that will protect the tree from insects and moisture. You will also need treatment with fire retardants that slow down the burning process of wood.

When the truss structure is installed, it is necessary to nail the crate. To do this, you can use both ordinary boards and plywood sheets or chipboards. It all depends on what kind of roofing materials you have. Also, further you need to deal with the bevels of the walls and internal partitions in the attic.

Create an insulating cake

Another work to keep in mind is creating an insulation layer. First of all, for this you need to lay the vapor barrier on the inside of the rafters and fix it with staples.

After that, the insulation material is laid, which must be laid close to the rafters, without leaving any gaps. On top of the thermal insulation, a step of 50 cm, the crate is stuffed - it is she who holds all the thermal insulation on herself.

The waterproofing layer is laid on the outside of the rafters, creating protection against accidental penetration of moisture. The final stage is laying the roof on the waterproofing layer.

The free space under the roof of the house can be converted into a residential attic. This is not only a rational option to turn the attic into a functional area, but also a great way to increase the usable area. Turning an attic into a room is not difficult today. Fortunately, there are advanced technologies and modern materials for this. Often, all work is carried out independently, taking into account the nuances of such a room. Arranging a free zone under a roof is useful not only from an aesthetic point of view, but also from a functional one. When carrying out work on the arrangement of the upper part of the house, the attic roof is additionally insulated.

Peculiarities

The popularity of houses with an attic is due to the peculiarity of the architecture of the building. The attic itself received its name from its founder, the French architect Francois Mansaroux, back in the 17th century. Since then, it has become convenient to use the last floors of buildings, although initially they were reserved for household needs, it was not a living or warm room.

Today it is quite possible here, for example, to equip an additional bathroom. But more often the room is modified for an additional bedroom, living room or playroom for children. The attic will never be a living room in the traditional sense, due to the broken roof and technical nuances. However, this does not prevent many from planning the construction of houses precisely taking into account additional meters, just in case. Like any building, an attic room in a private house has its own characteristics, advantages and disadvantages.

It is worth mentioning the following main advantages of a functional room in a private house:

• no need to build additional structures;
• the building is able to increase the area of ​​the house;
• no need to solve problems with sealing building;
• you can beat the design of the external appearance of the structure;
• even a two-tier design is reliable;
• heat loss is reduced (especially in winter it is noticeable);
• in the process of arranging the attic, as a rule, major repairs are not required.

When assessing the quality of the building as a whole, it will be useful to recall the shortcomings of the attic:

• sometimes this is not an opportunity to increase the space, but a clear "loss" of useful meters (mainly in old houses);
• problems can appear with sloped ceilings and walls;
• hydro and thermal insulation of the house leaves much to be desired (what to say about the attic);
• old skylights sometimes cause a lot of problems.

The peculiarities of the attic floor often consist in the fact that this room itself (more often in modern houses) extends almost along the entire perimeter of the house. In this regard, it is often necessary to modify or supplement the front of the house (parapets, niches, ledges, decorative elements) in accordance with the technical features of the roof. In individual construction, the possibility of completing or altering the attic roof is provided.

Types of roof structures

Individual construction is characterized by the use of various options for the roofing system.

Particular attention is paid to the construction of a mansard roof, which differs in the main types of structures:

• single or gable (broken, gable);
• hip and half hip.

The characteristic features for each type determine the possibility of arranging the attic.

Today, in addition to traditional ones, more modern forms are used:

• single-pitched mansard roof with an inclined area (mounted on load-bearing walls);
• a rigid gable roof attic with a slope on opposite sides;
• sloping roof (installation of a gable roof option);
• a hip or half-hip roof having four slopes (the end slopes of the hip roof differ in shape in the form of beveled triangles (the gable area is protected at the half-hip roof);
• pyramidal (also called hipped) types of roofs, which are not widespread, differ in polygonal shapes.

The shape of the roof is not the only distinguishing feature of the modern mansard roof. What matters is the height of the building and the nature of the coating (corrugated board, metal, you can make plastic tiles).

Separately, it is worth highlighting the universal distinctive features of the attic roof:

• it is not only the roof, but also the walls of the house;
• the maximum building height is not more than 2.5 m;
• the possibility of installing reinforced-plastic windows with tempered glass;
• multilayer structure;
• the cost of a mansard roof is, in the end, more than the usual one.

Even when designing a house, you can choose the most suitable roof shape, if necessary, lengthen the rafter legs (layering from the walls about 50-55 cm), calculate the loads and allocate space for windows.

Types and sizes

The highest point of the height of the under-roof space must be at least 2.5 m in order to consider this room as an attic. Otherwise, it is already an attic. According to SNiP, you can set the minimum value from ceiling to floor.

Differences in the types of attic roofs are determined by the following values:

• semi-attic - with a vertical wall height of less than 0.8 m;
• attic - with a wall height of 0.8 to 1.5 m;
• floor - with a wall height of more than 1.5 m.

The width of the structure is another major factor in determining the type of attic. The minimum norms in width are at least 80 cm.For a residential attic, this indicator (width) increases to 2 m, especially if the width of the house itself is at least 4.8 m.As for the building area, this parameter can be set using a special formula. Calculations are carried out in accordance with building codes and regulations. The area of ​​an ordinary attic cannot be less than 16 sq. m. The attic construction project covers all structural elements - roof slopes, retaining walls, gables, rafters. The type and size of the attic space is fully taken into account.

In general, the work on arranging the attic is as follows:

1. the roof is checked;
2. lathing is performed (made of wooden boards);
3. fastening of insulating materials is carried out;
4. the top of the rafter structure is strengthened;
5. stiffeners are checked (if necessary, replaced) - roof rafters;
6. beams are placed along the perimeter of the outer walls, they are connected to the rafter structure;
7. diagonal bevels (ties) are made to give strength to the attic roof;
8. the supporting supports are strengthened.
9. A waterproofing layer, insulation is being laid.

Calculating the useful area

When arranging the under-roof space, it is important to correctly calculate the area of ​​the attic room. The size, size, height of the attic, features of the angle of inclination have a close relationship in the calculations. Any redevelopment is carried out in accordance with the norms of SNiP. So, according to this provision, the minimum height of a dwelling under the roof is 2.5 m. The slope of the roof affects the calculation of the height of the room. Thanks to the calculations during the design, it is possible to reflect the real parameters of the upper floor of the house to obtain a useful area.

When calculating the area of ​​the attic, you can do it yourself, but the initial data will depend on the following parameters:

• the level of the slope is 30 degrees (in the narrowest part of the slope, the height is 1.5 m);
• the level of the slope is 45 degrees (in the narrowest part of the slope, the height is 1.1 m);
• the level of the slope is 60 degrees and higher (in the narrowest part of the slope, the height is 0.5 m).

To calculate the area of ​​the structure, the smallest height is taken a and multiplied by 0.7 (reduction factor). Then, for the minimum level of the walls of the attic with a slope of 30 degrees, an indicator of 1.2 m is obtained; from 45 to 60 degrees - 0.8 m; over 60 degrees - do not limit. It is important to remember that a successful attic project with a modern roof requires accurate and accurate calculations, for this you can use specially developed computer programs (a work scheme will appear before your eyes).

Design and materials

When choosing materials for the construction of an attic, timber is traditionally chosen; aerated concrete is also actively used. But there are other options for building and finishing materials for construction, the main thing is that it is a frame technology. The choice is made based on the type of structure and its size, the configuration of the roof and the slope of the walls are taken into account. For the frame of the attic, wooden rafters are best suited, moreover, it is important that they are perfect - without cracks and knots, especially without traces of decay.

As for the choice of aerated concrete, it is a fairly cheap and easy-to-install material. In addition, it is strong and durable. Aerated concrete blocks can be additionally processed with a special tool. However, due to lime, which is part of the material, aerated concrete cannot be classified as environmentally friendly materials. Instead, you can use corrugated board, foam blocks or vulture panels. The advantages of the foam block include a sufficient level of noise and heat insulation.

When arranging the under-roof space, competent design and drawings are of great importance. Modern mansard roofs are deservedly popular not only in summer cottage construction. More and more different options for small country houses with an equipped attic appear in our open spaces. It's all about the rationality and efficiency of such a room. Of interest are ready-made schemes for roofing structures, which imply an attic in a classic form, although the alteration of space, even in an old house, is not always capital. Most of the schemes are not very complicated, so the entire attic or balcony can be designed and done by hand. There are separate schemes for ready-made structures, where beams and floors do not even change.

Designing should be done at the initial stage of construction or repair. The attic floor is included in the project of the house. And the choice of the roofing type largely depends on how successful the building will be as a whole. The finished attic space can also be skillfully refurbished and equipped, turning it into a full-fledged functional room. Thanks to modern technologies and materials, it is not a problem today to design an attic floor in a finished house. The project can be selected by the type of attic.

Forms

The room under the roof has a special role to play so that it can be used comfortably.

To this end, a number of requirements are imposed on the attic under the attic:

• the shape of the attic should be as convenient as possible;
• you need to pay attention to insulation;
• room lighting is also important.

A competent layout will help to embody many useful ideas. The geometric shape of the attic has become a classic of the genre. Such a roof can be triangular or broken, with symmetrical or asymmetrical sides relative to the walls of the building. The floor itself can be located either on one side or across the entire width, even slightly going beyond the boundaries of the outer walls. Some of these projects involve the installation of additional support structures, for example, in the form of columns or walls.

In general, roof structures can be designed as follows:

• as a separate multi-level floor;
• a solid floor with a two-level development;
• a two-level floor with a mezzanine floor base.

The load-bearing walls of roof structures usually consist of two parts:

• a vertical wall (the wall material for the structure can be used the same as for the construction of the lower floors);
• an inclined wall (the rafter system serves as its frame, and the roof serves as an outer sheathing).

The ratio in the project of all these elements to each other depends on the design as a whole. The shape of the mansard roof gives the whole house a special look. Residential attic spaces can vary in the shape of the roof.

Basically, it is customary to distinguish the following types:

• single-pitched roof (without sidewalls, with a single under-roof room);
• a gable roof (a complicated structure that allows you to design a comfortable attic floor, taking into account the attic windows);
• sloping gable roof with a characteristic silhouette (slopes can be curved inward or curved outward).

A competent project allows you to "free up" the required usable area. It can be increased by installing a vertical, attic wall. It is worth considering that the useful area of ​​a hipped roof is less than that of a gable. This is due to the large number of bevels, which do not allow freely designing the under-roof space. It is optimal to use a typical attic project.

Since the height of the attic floor is important, it affects the usable floor space. In addition, the type of room under the roof is distinguished by height. For the big picture, it does not hurt to study the project of a typical attic structure in section.

Consider what it is.

1. If the height of the vertical wall of the roofing room is more than 1.5 m, then this is already a full-fledged floor. In the center of the structure, you can move freely without bending over. With a wall height of the attic of more than 2 m, we can talk about a functional room, which, in terms of comfort, will resemble a typical room.
2. If the attic has a single or gable roof with a height of attic walls of about 0.8 m (maximum up to 1.5 m), then such a structure is distinguished by increased functionality.
3. The presence of walls with a height of less than 0.8 m (or if there are no vertical walls) may indicate an insufficiently functional room.

There are several ways to turn the attic into a functional room, more convenient and rational. The general tone is also set by the interior of the under-roof room. Sometimes, for its arrangement, extraordinary solutions may be required, but it is better to follow well-known and proven rules in the work. So, the quality characteristics of the attic largely depend on the purpose of the room. For example, a small, narrow attic can be conveniently turned into an additional bedroom. A high attic allows you to equip an entire guest floor under the roof. It is also important what kind of furniture will be in the room and, accordingly, you can build in a wardrobe or put a rack.

It is important to comply with two general requirements:

• for a large room, the height of the walls to the floor from the ceiling is not less than 2.2 m;
• the height of the attic walls from the bed level is about 1.4 m.

A competent ceiling arrangement will improve the proportions of the room under the roof to the required ones (in accordance with the norms).

Device

The construction of an attic roof with your own hands implies a strong foundation and a reliable floor, the presence of reinforcing supports to relieve the load due to the attic floor (the attic needs to be additionally strengthened). Sometimes it is necessary to additionally strengthen the foundation of the house or redo a separate foundation. One cannot do without professional skills.

Stingrays

Even at the initial stage of the attic device, it is necessary to resolve all issues related to the design features of the building, taking into account all the partitions. The house can have ramps that affect the design as a whole. And the under-roof space itself can differ in a variety of forms. The interior decoration of the attic will depend on the features of the roof structure. If the roof of the house is designed in a special way, then you will have to remove the old rafters and materials, replacing them with new ones, taking into account the peculiarities of the project (the additional load, the angle of inclination and other structural features of the building are taken into account).

Rafter system

The entire rafter structure must be sized and designed for the type of attic floor. The best option for a typical house is the manufacture of an attic floor with a sloping gable roof. Such a roof has a large load on the walls, however, the combined area of ​​the attic is most often arranged in this way. At the same time, it is important to comply with the requirement for the presence of additional bearing supports (installation of inclined rafters designed for vertical and horizontal loads). When installing the rafter system, the Mauerlat is installed, after which the rafter legs are assembled and installed. The installation of the rafters is carried out, starting with two opposite legs, they are pulled over each other (the installation accuracy must be adjusted). This is how the frame of the rafter system is installed, after which the lathing is performed, which depends on the roofing material.

Roof

When arranging the upper floor, it is important to take into account the complexity of the attic roof. It differs from a typical roof by the fact that it bears the functional load of the residential and under-roof space. The ceiling of the house is a mansard roof with the necessary noise and heat insulation layers, with the finishing of the room. It should be as warm, comfortable, spacious and light as possible. Additional lathing of the roof structure will improve the quality of thermal insulation of the attic floor, although mineral wool can serve as the main insulation for this purpose.

High-quality finishing of the roof-ceiling depends on the purpose of using the attic. So, for example, lining, fiberboard, plywood sheets are traditionally used for giving. The decoration of living quarters is carried out with more substantial and expensive materials. Roofing material for exterior decoration creates comfort for the interior of the attic. In this case, slate, bitumen-based materials and modern tiles are traditionally used. It is better not to use metal sheets, they do not retain heat and create additional noise during rain and wind. It is also better to refuse roofing material, since in summer it heats up a lot, emitting a specific smell.

Window

The correct roof structure includes the arrangement of the windows. They are installed between the rafters. For the reliability of the window attachment points (bottom and top of the structure), horizontal jumpers are placed from the timber.

Installation of roof windows is carried out in stages:

• constructing an opening for a window;
• mount the frame with the dismantled glass unit;
• lay insulation and a layer of waterproofing;
• fastening the gutter of the window structure;
• install details;
• the dismantled glass unit is returned to its place;
• carry out interior decoration.

There is not always a constructive opportunity to build or expand the usable area of ​​the house by adding a full-fledged upper floor or side structure. To increase space in small houses, it is best to use the attic. It does not take up much space, but it allows you to "unload" the house a little, saving on construction costs.

In order to build an attic or make it out of an attic space, you need to stock up on materials:

• rafters are placed from wooden beams (with a section of 50x180 cm);
• the crate is made of a wooden board;
• the sheathing of the end walls is made of wall panels;
• we carry out fastening of roofing elements on self-tapping screws, nails, metal profiles and metal corners;
• during construction, heat-insulating, vapor-insulating and waterproofing materials are necessarily used;
• at the finishing stage, roofing material is used;
• at the end, the interior decoration of the room is made from modern facing materials, the main heating is installed.

Before starting work, it is important to make sure that the floors that are located between the first floor and the attic are sufficiently strengthened. It is necessary to calculate the loads. After making sure of the reliability of the fasteners, you can proceed to the arrangement of the rafter system. In the course of work, the quality of the connections of each element of the system is monitored. For a sloped roof project, support beams with end walls are installed first. After that, work begins on the collection of the frame structure of the rafter system.

Individual elements of the rafter system are fastened with a groove-ledge connection and with metal plates for greater reliability. All wooden elements can be used after special treatment for additional protection. Treatment with fire retardants is also required to reduce the flammability of wood structures. After assembling the rafter system, they proceed to processing the bevels of the walls and internal partitions.

An obligatory stage during the construction of the attic is the ventilation of the attic floor. It was enough for the attic to provide ventilation of the room. The attic building must meet the requirements of the living space. Ventilation problems can lead to heat loss, moisture condensation, and rot. All these external factors can lead to subsequent destruction. Simple ventilation is ineffective here; forced ventilation of the system and insulation is required.

Next, the arrangement of several layers of the attic roof is carried out: the very top is a roofing material, under it is a waterproofing material, lathing, heat-insulating and vapor-insulating material, ceiling decoration. It is important to emphasize that the sequence of layering must not be changed. Installation of insulation is carried out on the rafter system. There is a gap between the insulation and the roof for natural ventilation. In some cases, insulation (mineral wool and other fire-resistant insulator) is placed on the crate.

The thermal insulation layer in thickness is about 25-30 cm. For reliable fixation of this layer, an additional frame perpendicular to the rafters can be used. A vapor barrier in the form of a breathable membrane and a waterproofing material are attached at some distance from the insulation. It is worth considering that not only the roof should be insulated, but also the walls of the attic room to ensure greater comfort. The result is a "pie" that ensures the reliability and strength of the structure. The finishing of the roof-ceiling is done in the usual way - with plywood sheets, ceiling tiles, drywall, clapboard.

The decorative finish of the attic depends on the overall design of the room. Usually, the walls and ceiling are covered with wallpaper in the style of the decoration of the whole house. Walls can also be painted or plastered.

Warming and soundproofing

The main soundproofing in the attic room falls on the floors. Sound absorption is necessary to ensure comfort in the upper part of the floor, and so that excess noise does not spread to adjacent rooms.

For this purpose, old proven methods and new technologies are used:

• polyethylene foam with foil is laid on the logs (on one side);
• sand 5 cm thick is poured between the beams.

Competently executed sound insulation dampens shock noises from above, be it steps, falling objects. For sound absorption, mineral wool, foam or felt, as well as basalt slabs are often used. Vapor barrier and thermal insulation are also provided.

Due to the constant contact of the attic roof with atmospheric loads, summer overheating or winter cooling of the roof, it is necessary to carry out work on additional insulation of the attic. To do this, even at the stage of construction, a special protective layer of insulation and films against moisture is laid under the slate or other flooring. The main front of the attic waterproofing is carried out from the inside after the end of the main stage of construction.

It is important to leave a small space between the roofing layer and the insulation for natural ventilation. Today, additional external insulation of the attic is carried out with modern means so as not to reduce the usable area inside the attic building. The low weight of the insulation does not allow the structure to sag or deform. There are special heaters on sale - materials for spraying. They create an even, durable surface that prevents moisture build-up.

Finishing

Original and practical solutions for facing a wooden or brick attic space give free rein to imagination. The design of the attic is largely determined by the general design solution, but sometimes the most daring ideas are used. The cladding of the attic floor is primarily associated with the features of the finished structure. In this regard, the interior decoration of the attic has a number of features.

It is necessary to pay attention to several points.

1. The interior appearance of the attic is influenced by the presence of dormer windows. They are located on the roof slopes. An ordinary window is placed on a flat wall, the room acquires more light.
2. You can come up with unusual designs for the roof walls, for example, in colorful shades that contrast with the color of the ceiling or floor.
3. The bevels of the attic roof can be designed in a design way, emphasizing all the unusual design of the attic room.
4. The special atmosphere of the attic space is set by non-standard furniture (for example, irregularly shaped). A low, uneven cabinet fits perfectly in a narrow and low part of the attic.
5. The attic, which is large in area, can be divided into functional zones.

There are several roof options under which a comfortable living space can be placed. In order to ensure the maximum volume of the under-roof attic space, it is necessary to choose the optimal angle of inclination of the slopes and do not forget about the snow and wind load on the roof. We will consider the most popular designs of the attic rafter system in the middle lane.

The construction of the roof truss system

The mansard roof makes it possible to obtain additional usable space with a relatively small financial investment, therefore such an architectural solution has gained great popularity. So what is called an attic?

Mansarda (from the French mansarde) is an exploited attic space (both residential and non-residential premises), formed on the top floor of a house, or on the last floor of a part of a house, with an attic roof.

Wikipedia

https://ru.wikipedia.org/wiki/Mansard

The attic is located within the bearing walls of the building and rests on them through the Mauerlat, horizontal beams (ties) and rafters. The larger the attic space, the greater its useful volume, which is achieved by increasing the angle of inclination of the slopes and is formed by a more complex rafter system. The location of the attic roof rafters depends on the structure, which can be of different types, namely:

1. Hip or pyramidal structure with a minimum amount of roof space.

   The slopes of the tent structure rest on the side rafters and the central pillar, so the volume of the roof space is minimal here.

2. Hip or semi-hip roof, in which the main living space is under the trapezoidal slopes.

   The rafters of the hip roof form two triangular and two trapezoidal slopes

3. The gable structure, which is a symmetrical gable roof with gable cut in at right angles, which provides a significant volume of the attic space.

   Multi-gable roof allows you to equip a full-fledged attic floor

4. A symmetrical gable roof with an attic is a classic version, characterized by ease of installation and resistance to wind influences due to its rigid structure.

   The gable roof requires the least labor time and low consumption of building materials

5. The rafter system of the mansard sloping roof, providing the maximum amount of living space at a relatively low cost.

   A sloping roof is the optimal solution in terms of the ratio of the cost of construction to the volume of usable attic space

The rafter system must withstand constant loads, which consist of the weight of structural elements, insulation and roofing. In addition, there are variable loads depending on the strength of the wind and the weight of the snow on the roof. The choice of the cross-section of the bearing elements and the method of their connection should be aimed at creating the most durable and rigid structure that evenly distributes the load on the walls of the building.

Depending on the width of the building, different types of roof truss systems are used, which are divided into hanging, layered and combined.

1. Hanging rafters are called rafters, which rest on the walls of the building through the Mauerlat and the tightening, and form a ridge in the upper part. With this method of connection, there is no intermediate support, and the expanding pressure on the walls of the house is reduced with the help of crossbars, struts and struts. The hanging rafter system is usually used when the building is no more than 6 m wide.

   To compensate for the bursting forces in hanging rafter structures with a span of up to 6 m, puffs and crossbars are used

2. Rafters are called rafters with intermediate support on the inner wall of the house. They are used when the width of the building is from 6 to 16 m. The larger it is, the more elements are used to evenly distribute the load.

   Rafters have one or more supports inside the house

3. The combined type of rafter system is used in mansard roofs with a variable angle of inclination of the slopes. The most typical example is the sloping attic roof, where the lower rafter legs are layered with support on the rack and Mauerlat, and the upper ones are mounted as hanging rafters with support on the puff and the headstock. When erecting mansard roofs, all types of rafter systems are used, and their choice depends on the design in which they are used.

   In the construction of a sloping roof, the upper rafters are hanging, and the lower ones are layered

Mansard roof truss system diagram

To erect a roof, you must have a project that contains the list and size of structural elements, as well as the way they are connected. To understand the principle and sequence of installation, you need to know the purpose of the elements of the rafter group and the way the roof adheres to the walls of the building. A mansard roof consists of the following elements:

• the connecting element between the wall of the building and the rafter group is the Mauerlat, which is attached to the walls of the house with pins, brackets or anchors;
• puffs are attached to the Mauerlat parallel to the short wall of the building, and rods are installed along the long side;
• vertical racks are mounted on the central bed;
• the ridge girder rests on the racks;
• the upper part of the rafters rests on the ridge girder, and the lower part is connected with a tightening, forming a cornice overhang;
• rafter legs in the upper part are connected with crossbars;
• on hip roofs, diagonal rafters and shortened rafters are used;
• sprengles serve as additional support for the diagonal rafters;
• for intermediate fastening of rafters, racks and struts are used;
• if necessary, the rafters are extended by fillets.

The main load-bearing elements of the attic roof are rafter joists, beams and braces, as well as vertical posts and a ridge girder.

The diagram indicates the dimensions of the elements of the rafter system, their location, angles of inclination and methods of insertion in the nodes of the connection. Information on the location of the double rafters, the availability of additional supports, the dimensions of the eaves and gable overhangs is also required.

The diagram is the main document for assembling the rafter system, it reflects all the necessary parameters. However, before cutting the material, it is necessary to double-check the calculations and create templates for the main parts. In the absence of a project, you need to carry out calculations and create a scheme yourself.

Mansard roof rafter step

Before starting work, you need to choose the step of the rafters of the attic roof. The distance between rafters and rafters (in the case of a hip roof) depends on several factors:

• the size of the building;
• type of rafter system;
• constant and variable load on the roof;
• sections of rafters, racks and cuts;
• type of roofing;
• type and pitch of the crate;
• the size of the insulation.

For rafters, lathing and counter-battens, coniferous material is selected in accordance with SNiP II-25, and the load on the rafters is calculated according to SNiP 2.01.07 and ST SEV 4868. Based on what is stated in building codes and regulations, we can say that for rafters less than 9 m, the cross-section of the timber is applicable from 50X150 to 100X250 mm with a step from 60 to 100 cm.The size of the building affects the structure of the truss and the presence of racks, struts and crossbars, the use of which increases the strength of the rafter legs and allows you to increase the step between the rafters to 120 cm or more ... Usually, reference tables are used to select a step, which contain recommendations taking into account the length of the rafters and the section of the timber.

Table: dependence of the pitch between the rafters on the section of the timber and the length of the rafters

The type of roofing used also affects the choice of the pitch of the rafters, because different materials have different weights:

• tiles, depending on the type, weigh from 16 to 65 kg / m 2, slate - 13 kg / m 2. Such heavy coverings imply a reduction in the pitch of the rafter legs to 60–80 cm;
• the weight of metal coatings and ondulin does not exceed 5 kg / m 2, so the pitch of the rafters can be increased to 80–120 cm.

On hip roofs, the step of the beaters is in any case chosen equal to 50–80 cm to give the ramp more rigidity.

In addition, the step of installing the rafters depends on:

The length of the rafters and lathing of the attic roof

With independent calculations, the dimensions of some structural elements of the roof have to be calculated according to the existing dimensions of the building and the angle of inclination of the slopes. The length of the rafters sometimes has to be adjusted for different types of attic roofs, selecting the optimal dimensions for the entire structure as a whole.

Suppose that the main dimensions of the building are known and it is necessary to calculate the length of the rafter logs for several proposed options for the angle of inclination and type of roof. Let half the width of the building L be 3 m, the size of the eaves slope - 50 cm.

Additional calculations show that an increase in the angle of inclination of the lower slope from 60 to 70 o will increase the width of the attic by 10%.

The length of the lathing connecting the rafter legs is determined taking into account the gable overhangs that protect the walls of the facade from precipitation. The length of the gable overhang depends on the height of the building and is chosen in the range from 40 to 60 cm. Therefore, the total length of the slope will be equal to the length of the house, increased by twice the length of the overhang.

Suppose that the length of the house is 10 m, and the pediment overhang is 0.6 m.Then the dimensions of the crate must be calculated taking into account the length of the slope, equal to 10 + 0.6 ∙ 2 = 11.2 m.

The parameters of the lathing should be calculated taking into account the length of the pediment and cornice overhangs

Any adjustment to the project requires a careful recalculation of the parameters of the rafter system, taking into account the changes that have occurred.

Video: calculation of the attic roof

Nodes of the roof truss system

The nodes of the roof truss system are the place where individual elements are connected into a single structure, which allows you to evenly distribute the load on the walls of the building. The connection is made with nails, screws or bolts using overhead wooden elements or metal squares and plates, as well as by connecting into a groove. For the construction of a gable roof, the following main nodes are used:

1. The ridge knot, which provides the connection of the rafter legs between themselves and the ridge run.
2. Places where the crossbar connects the rafters to give greater strength and rigidity to the rafter trusses.
3. Attachment points for struts and struts, which give additional support to the rafters.
4. Cornice knot, in which the rafters are attached to a puff or Mauerlat, forming a cornice overhang.

The nodal connections of the rafter system should be made so that the most rigid fastening of the elements to each other is provided

For a gable sloping roof, a node is characteristic where the upper and lower rafter joists, a vertical post, a girder and a girder are connected. Such a complex connection requires the use of mortises, bolts, steel plates and construction brackets.

In the most complex node of the sloping attic roof, five rafters are connected

The most difficult knot of the hip mansard roof is the junction of the lateral or diagonal rafter legs with the Mauerlat. The side rafter in the lower part rests on the Mauerlat corner beam and on the embedded beam; in another version, a vertical stand or truss is placed between the embedded beam and the rafter leg. The top of the hip rafters is attached to the ridge girder with bolts or nails.

The angular rafters of the hip roof carry the greatest load, so the node of their connection with the Mauerlat must be thought out most carefully

The described nodes are used most often when installing rafter systems of various designs and allow the installation of load-bearing elements on their own. For an efficient and high-quality assembly, drawings and the manufacture of templates with verified corners of joints and tie-ins are required.

Video: nodes of the truss system

Calculation of the roof truss system

The rafter system is the basis of the roof, therefore it is important to choose the structure that best suits the climatic conditions of the region and the existing requirements for the size of the residential attic. After choosing a design, the angle of inclination of the slopes and the height of the ridge are calculated for the required dimensions of the attic. Calculations are made taking into account the size of the cornice according to the following formulas:

The meaning of trigonometric functions can be found in the reference tables.

Table: values ​​of trigonometric functions for different slope angles

The most difficult thing in the design of mansard roofs is the calculation of lumber. It is sometimes quite difficult to calculate the number of necessary rafters and link them to the standard length of 6 m. Let's say that we have chosen the most difficult hip roof in the calculations, measuring 10X13 m, taking into account the eaves overhangs 80 cm long and the slope angle of 45 °. Then the side rafters will have a length of 5 / sin 45 o = 7.04 m. Therefore, the standard six-meter beam will have to be lengthened. Usually for rafters with a length of slightly more than 6 m, a beam of 100X200 mm or a board of 50X250 mm is used.

If the building is large, then it requires rafters longer than the standard size of 6 m, so the beam has to be lengthened

As for the horizontal floor beam, since the width of the building is 10 m, the puffs must consist of two parts, which either rest on the inner wall of the building, or are joined together by reinforcing elements and rest on the girder. For puffs and girders, a bar with a cross section of at least 50X200 mm is used. A mauerlat runs along the perimeter of the building, for which a beam of 150X150 mm or 200X200 mm is used. According to the scheme we have chosen, the perimeter of the building is 39.6 m, so seven six-meter beams will be required for the installation of the Mauerlat. The dimensions of all other elements of the rafter system will not exceed 6 m.

The weight of the lumber of the truss system is calculated by summing the lengths of all elements with a certain section and recalculating their number in cubic meters. This is necessary to determine the mass of the entire roof, and it is also necessary when purchasing and transporting material. The calculation is made according to the table, and then the obtained values ​​are multiplied by the weight of 1 m 3 of sawn timber.

Table: calculation of the amount of lumber in 1 m 3 and the volume of one unit of material

Pine lumber at 12% humidity weighs 505 kg / m 3, with a transport humidity of 25% - 540 kg / m 3. Here are some examples of calculations:

1. If 1 m 3 of material with a section of 50X200 mm contains 16.6 boards, then the weight of one board will be equal to 540 / 16.6 = 32.5 kg.
2. If 25 m 3 of sawn timber is purchased, then it will weigh 25 ∙ 540 = 13 500 kg.
3. If you need 100 boards 25X200, then you need to buy 100 / 33.3 = 3 m 3 of wood, which will weigh 3 * 540 = 1 620 kg.

It is important to note that it is advisable to purchase edged lumber with the lowest moisture content, so that after installation it does not warp or crack, especially when it comes to a large section bar. For the construction of the truss system, the moisture content of the wood should not exceed 18%.

Installation of the roof truss system

Installation of a truss system with a residential sub-roof space requires careful preparation. It is necessary to install comfortable scaffolding, decks and ladders, as well as provide workplaces with safety ropes. Workers must be provided with overalls, protective equipment and serviceable equipment. On the ground, you need to choose a level place for pre-assembly of trusses, marking of corners and making templates. All wooden elements must be treated with antiseptic and fire-fighting compounds.

After that, you can start work, which takes place in the following sequence:

1. The Mauerlat is mounted on walls with walled studs along the perimeter. If there is a load-bearing wall inside the building, we lay a bed or a run of the same height with a Mauerlat on it.

   If the house is being built from building blocks, then the Mauerlat is most conveniently laid on threaded rods wedged into the wall during its masonry

2. Puffs with eaves are attached to the Mauerlat parallel to the short wall.
3. On the puffs, vertical racks are exposed, limiting the attic room.
4. The racks are connected with a tie that serves as the ceiling of the attic room. The trusses installed in this way are interconnected by horizontal girders.
   

   Vertical uprights, top braces and horizontal purlins form the frame of the attic room

5. The lower, and then the upper rafters are installed, which are attached to the ridge part.
6. To strengthen the lower and upper rafters, struts, headstock and beads are used.
7. The crate and the frontal board are mounted on the eaves overhang.

   After installing all the rafter lags, it remains to lay the crate and nail the frontal board

We examined the assembly of the truss system using the example of a sloping mansard roof. The construction of other structures consists of similar operations and mainly consists in performing work according to the design installation diagram, which reflects the methods of connecting the elements of the rafter system. In the presence of carefully calculated drawings, a team of four people is able to mount a roof with a rafter system of any complexity.

Video: installation of a mansard roof

We examined the rafter group of the attic roof, its structure, calculation, as well as a diagram and description of the main units. They offered a variant of the step-by-step installation of the attic supporting structures, attached illustrations and videos that explain the assembly procedure for the attic roof structural elements. Now, its successful erection depends only on the thoroughness of fulfilling the requirements of instructions and technologies and the availability of certain skills in carrying out construction work by the performers. We wish you every success.