Ttk. device of a gable roof during the construction of an individual residential building

Rules for installing rafters of the layered type

Spacer rafters in their design practically do not differ from the three options described above, with the exception of one caveat: instead of rigid fastening of the rafters, you need to use a movable mount. Spacer rafters of this type differ in that it is not necessary for them to install a purlin. For the spacer system, you need to very carefully fix the Mauerlat to the walls of the house. However, they must be thick and strong.

A little about the layered rafters with struts. They represent the third rafter leg, which works in compression, and is installed at a 45-degree inclination. As a result, even 14-meter spans can be overlapped, while beams can be used with not the largest sections.

There is no need to calculate the fastening of the struts, you can simply fix them on both sides by placing them under the rafters. This will prevent the brace from shifting.

You just need to cut the angle of the brace evenly, taking into account the slope of the rafters. To determine what section the nodes of the layered rafters are needed, the pressing force is calculated.

The last type of layered rafter systems include structures on rafter beams.

If your house has two load-bearing walls, you will need to install two truss systems. These include beams mounted on the longer side of the roof. Racks are mounted under the beams, and a bench and located inside the walls of the house serve as supports. In the absence of girders, the racks are installed under all rafters. The tops of the rafter legs are connected to each other, after which they are tied with overlays of wood or steel. In the absence of a ridge girder, a thrust is created.

The tightening is installed below the through run - in this way, they get rid of the thrust in the non-thrust system. From the bottom of the racks, to improve stability, the contractions are fixed. They act as a transom, taking on compression loads and preventing the struts from falling. Cross-linking is fixed.

In this article, we talked in detail about how to strengthen the rafters of a gable roof, what such systems are, and how to install them.

What criteria should the filly of the roof meet? ↑

• For the manufacture of this structural element, solid wood is used without significant flaws, which is recommended to be coated with antiseptics and a primer before installation. This treatment prevents rotting and prolongs the service life of this element of the roof.
• They not only need to be reliable, but also be able to withstand the load. At the same time, the rafter legs should not be overloaded.
• Parameters of lumber for a filly: in width, these boards are several centimeters smaller than the material for rafters. In length, they should be more than the length of the overhang by about 50 cm, which are necessary to make the joint with the rafters.
• The installation of the elements is carried out in accordance with the requirements of SNiP in order to ensure the reliability of the roof and the durability of the building.
• They must fit into the design of the roof, in harmony with the coating material.

Recommended
If filing with finishing material is not provided for a box of this type, then it is advisable to use calibrated boards with a size of 50x20 mm for filing a box.

Shed roof rafter system

Such roofs are especially popular in the construction of yard buildings - sheds, garages. It's just that the size of the buildings allows the use of not very powerful beams, and beams are required in small quantities. With a building width of up to 6 meters, the shed roof rafter system contains almost no additional reinforcing elements (supports and girders), which is beneficial. Also attractive is the lack of complex knots.

For Central Russia, for a span of up to 5.5 meters, beams of 50-150 mm are taken, up to 4 meters, 50-100 mm is enough, although in an amicable way, you need to consider the snow and wind load specifically in your region, and, based on this, determine with the parameters of the beams.

Shed roof rafter system with a small span (up to 6 meters)

With a distance between the walls up to 4.5 meters, a pitched roof consists of two Mauerlat bars fixed to the walls and rafter legs, which rest on the Mauerlat. A very simple construction indeed.

With a span width of 4.5 meters to 6 meters, a bed is also required, fixed on a higher wall at the level of the ceiling and a rafter leg, which rests against the beam almost in the middle. The slope angle of this beam depends on the distance between the walls and the level of installation of the slope.

More complex rafter systems in a pitched roof with a building width of more than 6 meters. In this case, it is optimal if the house is designed so that inside there is also a load-bearing wall on which the racks rest. With a house up to 12 meters wide, the trusses are still simple and the roofing costs are minimal.

Construction of pitched roof trusses with buildings more than 6 meters wide

For buildings more than 12 meters wide, the system becomes more complicated - there are more rafter legs. In addition, making beams over 6 meters long is expensive. If an increase is required only by the width of the roof overhangs, the beams are grown along the edges with fillets. These are pieces of beams of the same section, connected to the beam and fixed on the sides by two wooden plates at least 60 cm long, fastened with bolts or nails, allow the use of mounting plates.

Rafters splicing option

If the total length of the beams is more than 8 meters, they are usually spliced. The joints are additionally reinforced by nailing boards or mounting plates.

Options for attaching the rafters to the Mauerlat: sliding glory at the top and rigid at the top right. At the bottom right, the option of a tie-in without overhangs (used very rarely)

There may still be questions about how to attach the rafters of pitched roofs to the Mauerlat. There are no fundamental differences. All the same, a cutout is made in the rafter leg, with which the bar rests against the Mauerlat. In order not to suffer with each rafter leg, leveling its landing, sawing out the first one, from a piece of board, thick plywood or timber they make a template that exactly repeats the resulting "drank". All subsequent rafters are filed before installation. A template is applied to them in the right place, a recess of the required shape and size is circled and cut out.

This was a question of rigidly attaching the rafter legs to the Mauerlat. It is used on all buildings that exhibit low shrinkage. On wooden houses, this method of fastening cannot be used - the house settles all the time or rises a little, which may cause a distortion. If the roof is fixed rigidly, it can break. Therefore, when installing a shed or any other roof on wooden houses, a sliding connection of rafters and Mauerlat is used. For this there are the so-called "sliding". These are plates, a state of corners that are attached to the Mauerlat and metal strips movably connected to them, which are attached to the rafter leg. Two such slides are placed on each rafter.

Hanging rafter system

This design is characterized by the fact that the side walls act as supports for the rafters. A negative nuance is that there are bursting loads, which after a while can damage the walls. To prevent this, the connection of the rafter legs is carried out using puffs. Thus, a rigid triangle is created that does not deform due to loads, and the hanging rafter system of the gable roof remains reliable and stable. Often, puffs are replaced with floor beams, this is especially required if you plan to build an attic under the roof.

Such a gable roof truss structure has positive aspects, namely, it is possible not to mount the Mauerlat.In addition, it is quite simple to install the structural units in which the rafter legs rest on the walls. To give the truss even outlines and stability, a board is laid through the insulation layer, thereby increasing the support area. Below we describe the main types of three-hinged hanging rafters.

The first type can be attributed to the usual triangular three-articulated arch. This design is uncomplicated - it is a closed triangle with two upper sides designed to resist bending loads. Instead of tightening, a steel tie can be used in this structure. The cornice assembly can be made using one of the existing design solutions: using an orthogonal frontal cut or using plank or plate fasteners.

What is it and what is it for?

It, in turn, serves to drain water from the walls of the house, preventing them from getting wet. This not only prolongs the service life of the enclosing structures, but also does not impair their thermal performance, which is of particular importance for most climatic regions of our country. In addition, every visible element of the roof affects the aesthetic perception of the building as a whole, and filly can also become bright decorative details.

No one doubts the need for cornices, while not everyone is a supporter of their device using filly. Another logical design option is to use longer rafters, sufficient to organize the overhang. It is the possibility or impossibility of acquiring a board (timber) of sufficient total length that often becomes decisive in this matter. As an additional argument, the supporters of this design usually cite the consideration that the reliability of the whole rafter will be higher than that of the composite one. However, in this case, one should not forget that, by abandoning the fillies, you are acquiring a more complex cut of the rafters in the Mauerlat.

The filly connection scheme.

One way or another, many people decide to organize roof overhangs with the use of filly. And for good reason, because this structural element gives us several advantages:

1. Wood under the rafters is taken only of the required length from the ridge to the Mauerlat, which reduces their overall cost. Fillets are made from a cheaper board with a section of 5 by 10 cm.
2. Due to the shorter length of the rafters, their lifting and installation is simplified.
3. With short fillets, it is simple and easy to draw the exact line of the overhang.
4. In the event of problems with filly already during the operation of the building, it is easier to replace only them than all damaged parts of the truss structure, which would require a complete dismantling of the roof.
5. It becomes possible to increase the aesthetic appeal of the house by using a particularly beautiful element - carved filly.
6. The use of a filly allows you to "break" the roof line coming from the rafter and thereby achieve a certain aesthetic effect.

3 Roof with two slopes - types of truss systems

A more common option for a rafter system for a private house is a gable roof. The performance of the main functions of the roof depends on the reliability and strength of the frame: whether it can withstand wind and snow loads. It is necessary to correctly calculate the distance between the rafters, the angle of inclination, select the material with the required section, taking into account the weight of the material with which the roof is covered, and climatic conditions.

When calculating the load on the rafter system, it should be borne in mind that there are three types of it:

1. 1. Constant. It includes the weight of all blood elements: waterproofing, insulation, roofing material, additional elements, finishing materials. On average, it is 40-45 kg per square meter.
2. 2. Variable. These loads include wind loads, snow loads, and loads during precipitation. In contrast to the gable roof, the hip roof does not experience high wind loads.
3. 3. Special. Calculated in places with seismic activity, storm winds, tornadoes, etc.

Gable roofs are classified by the type of slope and by the way the rafters are supported. The roof configuration can be simple with straight slopes, asymmetric and broken.The simplest in execution is a roof with straight slopes, but it loses in the free area of ​​the attic space. When a gable roof with an attic is being built, it is better to choose a roof with broken slopes that have a line where the angle of inclination changes. By reducing the angle of inclination in the lower part, you can increase the free space of the attic.

According to the way in which the supporting elements are supported, the rafter systems are divided into types: layered and hanging.

Forced. These roof truss systems allow small houses with a width of up to 14 meters to be covered. The rafters of such a frame have two supports: with the upper end they rest on the ridge girder, and the lower end on the Mauerlat. The device of a rafter system of a layered type is possible for houses with the greatest length of the house, which does not provide for the reinforcement of the central transom, as well as for buildings that have at least one load-bearing wall or columns inside. Only the bending load acts on the rafters of the slab, which can be reduced using various struts.

Hanging. There are no supporting elements in this design, which makes it possible to use the free space rationally. Only the lower ends of the rafters rest on the Mauerlat, the upper ends remain suspended and reliably connected to each other, resembling the installation of trusses. Hanging rafters experience bending and expansion stress, which is compensated by the use of crossbars and ties that tie the rafter pairs together. For the device of a gable roof of a suspended type, triangular trusses are used, which, due to their rigid shape, are not subject to loads.

Determine the height to which you want to raise the wall

To ensure the found slope angle of the pitched roof, it is necessary to raise one of the walls higher. How much higher we learn by remembering the formulas for calculating a right-angled triangle. On them we find the length of the rafter legs.

How to calculate the parameters of a shed roof

When calculating, do not forget that the length is obtained without taking into account the overhangs, and they are needed to protect the walls of the house from precipitation. The minimum overhang is 20 cm. But with such a small ledge outside the building, the lean-to roof looks scanty. Therefore, overhangs of at least 60 cm are usually made on one-story buildings. On two-story ones, they can be up to 120 cm. In this case, the width of the overhang is determined based on aesthetic considerations - the roof should look harmonious.

An example of a drawing in ScratchUp

The easiest way to determine how much you need to extend the roof in design programs that allow you to draw a building to scale and "play" with overhangs. Everything should be displayed in 3 dimensions (the most popular program is ScratchUp). Twist different sizes of overhangs in it, decide which one looks better (if there is no project), and then order / make rafters.

Shed roof device

The required slope of the pitched roof is organized due to the difference in heights of the opposite walls. One wall of the building turns out to be much higher than the other. This leads to an increased consumption of materials for the walls, but the rafter system is very simple, especially for buildings of small width.

Shed roof for barn

With sufficient bearing capacity of the walls, the shed roof rafter system rests on a Mauerlat fixed to the wall. To distribute the load more evenly, the upper row of the wall masonry is reinforced with longitudinal reinforcement (for brick walls, from concrete blocks) or an armopoyas is poured over the last row (for walls made of lightweight concrete, limestone, shell rock). In the case of a wooden or frame structure, the role of the Mauerlat is usually performed by the last crown or upper strapping.

With insufficient strength of the building material of the walls, most of the load can be transferred to the floor.For this, racks are installed (step - about 1 meter), on which the girders are laid - long bars running along the building. Then the rafter legs rest on them.

How to transfer the load from the walls to the floor

When pouring an armored belt or laying the last row, studs are installed in it, with a step of 80-100 cm, with which the Mauerlat is then attached to the walls of the building. In wooden houses, if you do not make an armored belt, it is impossible to lay studs. In this case, installation on hex pins is allowed. A hole is drilled under the pin through the Mauerlat, a couple of millimeters less than the pin diameter. A metal rod is hammered into it, which attracts a wooden beam to the wall. The connection is tightened with the correct size hex wrench.

4 We install the gable roof truss system - technology

Before installing the frame, you need to correctly calculate the snow and wind loads, the angle of inclination of the roof, the length, pitch and section of the rafters, and calculate the required amount of lumber. The calculation of the gable roof rafter system will be performed in the following sequence:

We select the structure and determine the optimal angle of inclination of the roof, it depends on the climatic conditions and the material used for the roof. For a soft roof, the slope of the roof is from 5 to 20 degrees, for corrugated board, metal tiles, slate, ondulin - from 20 to 45 degrees.

We calculate the maximum possible load, which includes a constant load (roof weight) and temporary (snow and wind), multiply by a correction factor taking into account the angle of the roof slope. Add 10% to the result so that there is a margin of safety for the frame.

Using the Pythagorean theorem, we calculate the length of the rafters. The square of the length of the rafter is equal to the sum of the squares of half the length of the laying and the height of the roof. Knowing the length of the rafter legs, you can calculate the height of the ridge.

We choose the section of lumber depending on the length of the rafters, possible loads and the pitch between the rafters. The higher the indicators, the larger the section should be. There is a special table for calculating the cross section.

The roof rafter system with two slopes includes the following elements: mauerlat, bed, rafters, struts, racks, tightening.

When all the elements of the rafter system are ready, we prepare the drawings and proceed with the installation, which we divide into several stages:

1. 1. Mount the Mauerlat. A Mauerlat is laid on the upper belt of the outer walls, which will serve as a support for the roof. Since the length of the lumber is less than the length of the Mauerlat, we splicate two pieces of the Mauerlat. We cut the saw cut at a right angle. The connection is made using bolts. If the layered type is chosen, then we mount the bench along the internal partitions. All elements are securely fixed with studs or anchor bolts.
2. 2. Next, we mount the rafter legs, fixing them in the knots with nails and fastening them together with a metal plate. In the rafters, we make a drink in advance for attaching to the Mauerlat. The first are the extreme rafters, along which we align the rest with the help of a level.
3. 3. When the rafters are installed, we mount the auxiliary supporting elements: puffs, struts, contractions. To securely fix the crossbar, we make it so that its end protrudes by half the thickness of the bar, then we adjust it to the rafter, fixing it with nails.
4. 4. On the finished truss system we fill the sheathing, we put the roofing material on it. We choose the step of the lathing depending on the type of material with which the roof is covered, its performance characteristics. Under the metal tile, the step is 35 cm, under the slate and corrugated board - 45 cm, under the soft roof we fill in a continuous crate.

Do-it-yourself installation of a gable roof is easier than a gable.But a roof with two slopes looks more aesthetically pleasing. In addition, it makes it possible to use the attic space for arranging the attic. The further operation of the house depends on the quality of the roof, therefore, if you do not have sufficient experience in roofing, it is better to turn to specialists.

Installation of racks.

4. Installation of fillies.

On this, the installation of the rafter system can be considered complete.

1 Shed roof - the main nuances of construction

Roofs with one slope are used mainly in the construction of outbuildings: garages, sheds, household structures. The advantages of a pitched roof are simplicity of calculations, simple installation, low material costs, resistance to wind loads, the possibility of self-erection, maintainability.

The shed roof structure includes two Mauerlats and rafter legs. If the spans are large, then it is necessary to add additional elements that increase the load-bearing capacity of the roof, which strengthen the rafter system: struts, racks, fights, girders, beds.

When calculating the cross-section for the construction of a pitched roof in a private house, it is necessary to take into account the weight of the roof, wind and snow load. On average, the following recommendations should be adhered to:

• With a span length of less than 4.5 meters, we use solid rafters made of logs with a diameter of 120-180 mm and boards hewn from them, a bar with a section of 100x100 mm.
• If the span length is in the range from 4 to 6 meters, for the rafters we use logs with a diameter of 180-200 mm and hewn plates, and a bar with a section of 150x150 mm. Sometimes you can get by with the standard six-meter length of the bar.With a significant angle of inclination and a span length of about 6 meters, we join the rafter legs along the length. We use struts as additional fastening.
• If the spans exceed 6 meters, we make intermediate racks, on which the load will fall, thus, the beam will sag less. In this case, the calculation is carried out, taking into account the intermediate supports. For the rafters, we take the material of the same section as for spans up to 6 meters. In this case, we are building the rafters along the length.

The following parameters of the bar are recommended: for a Mauerlat with a side of 180-200 mm, for supports with a section of 80x80 cm.

The distance between the rafters depends on the load on the roof, the presence of roof windows, the heat insulator used. We divide the slope on which the rafters will rest into equal parts so that there is the same step between the rafters. The longer the spans are, the less we step between the rafters. The following step values ​​are recommended for insulation:

• mineral wool - 58 cm;
• extruded polystyrene foam and foam - 60 cm;
• for polyurethane foam, the step is not important.

The angle of inclination of the roof slope depends on the roof material. The higher the angle of inclination, the less chance of leaks. For bituminous tiles, the optimal angle of inclination will be 20-45 degrees, ceramic - 30-45 degrees, for metal - 20-45 degrees, for slate - 6-27 degrees, for galvanized sheets - from 14 degrees.

Why shed

The roof structure of 1 slope has the following advantages:

• When building on a pitched roof, any kind of roofing material can be used. Because the angle of inclination can be as small as possible, an almost flat roof can be built.
• The sail of this design is much less than that of the dual-slope. This option can be used in areas with strong winds.
• Ease of installation and operation. You can build it yourself.
• Low weight compared to other types of roofing.
• For a pitched roof, slopes can be built in several floors. This solution will add design to your home.
• The construction of a pitched roof is the most economical and does not take much time.
• In this design, the water rolls down only to one side.
• The roof is suitable for any type of building.

Like any other design, a pitched roof has several disadvantages:

• With a small angle of inclination, the area of ​​the attic is minimal.
• Has a less attractive appearance. What can be fixed if there is a designer's imagination.

Installation process

The construction of the roof frame, in which it is planned to use filly to lengthen the rafter legs, is carried out according to standard technology. After installing the rafters on the Mauerlat, it is necessary to prepare the filly - their number should correspond to the number of rafter legs.

The size of the filly depends on the roof project - the length is chosen in accordance with the planned width of the overhang, and 30-50 cm is added to it for fasteners. The longer the filly, the more there must be a reserve for fastening in order to ensure the rigidity of the structure and to exclude the subsidence of the roof edge under load. For their manufacture, use a board of a suitable section or trimming the timber remaining from the installation of the rafters.Fillets are mounted at the final stage of the roof frame construction:

A filly template is prepared, according to which the required number of elements is cut out. Each of them is treated with a fire retardant composition.
The filly is mounted on the rafter legs with an overlap of 30-50 cm, aligning the upper ends of the elements. They can be fastened with brushed or ordinary nails.

It is important to provide high-quality adhesion for which four nails are used for each knot. They are driven in two on each side

The ends of the nails should be bent so that the fasteners do not weaken over time. Bolts are also used for fastening. An example of using bolts for fastening filly with rafters
First of all, the extreme filly is attached to the slope, carefully measuring the size of the overlaps.Then a cord is pulled between these elements and the rest are mounted on it. The method is suitable for stingrays of relatively short length, on which the cord will not sag.
If the overhang design involves the use of consoles, the end of the filly is fastened flush with the horizontal beam.
To strengthen the roof overhang, a frequent or continuous sheathing is mounted on top of the fillies, which adds rigidity to the structure.
After the completion of the roofing device, the cornice is hemmed.

Correctly hemmed with soffit, siding or boards, the cornice looks aesthetically pleasing, does not allow moisture to get onto the rafter system and does not interfere with the free ventilation of the roof. There are two options for filing the eaves:

1. diagonal strips are mounted directly on the filly;
2. horizontal support bars are pre-installed on the wall of the building to create a box and the filing elements are fixed perpendicular to the wall.

Diagonal filing of the roof overhang

At the final stage, the end part of the eaves box is sewn up, a wind angle is installed along the slope - these elements protect the roof frame from drops during slanting rains, do not allow strong winds to blow through the structures with noise and give a complete look to the appearance of the roof.