The scheme of the assembly of the roof of the house. Self-construction of the roof of a private house

Roof installation is a complex multi-stage process. In order to independently assemble and install the truss system, it is necessary to carefully study the methods of connecting the elements, calculate the length of the rafters and the slope angle, and select the appropriate materials. If you do not have the necessary experience, you should not take on complex designs. The best option for a small residential building is a do-it-yourself gable roof.

A standard roof of this type consists of the following elements:

Mauerlat is a beam laid on top of the walls along the perimeter of the building. It is fixed with threaded steel rods immured into the wall or anchor bolts. The beam must be made of coniferous wood and have a square section of 100x100 mm or 150x150 mm. Mauerlat takes on the load from the rafters and transfers it to the outer walls.

rafter legs- these are long boards with a section of 50x150 mm or 100x150 mm. They are attached to each other at an angle and give the roof a triangular shape. The design of their two rafter legs is called a truss. The number of farms depends on the length of the house and the type of roofing. The minimum distance between them is 60 cm, the maximum is 120 cm. When calculating the pitch of the rafter legs, one should take into account not only the weight of the coating, but also the wind load, as well as the amount of snow in the winter.

It is located at the highest point of the roof and most often represents a longitudinal beam connecting both slopes. From below, the timber is supported by vertical racks, and the ends of the rafters are attached to the sides. Sometimes the ridge consists of two boards, which are nailed to the top of the rafters on both sides and connected at a certain angle.

Racks - vertical bars with a section of 100x100 mm, located inside each farm and serving to transfer the load from the ridge run to the load-bearing walls inside the house.

The struts are made from timber scraps and set at an angle between the uprights and the rafters. The side faces of the truss are strengthened with struts, the bearing capacity of the structure is increased.

Puff - a beam connecting the lower parts of the rafters, the base of the truss triangle. Together with struts, such a beam serves to strengthen the truss, increases its resistance to loads.

Lying is a long bar with a section of 100x100 mm, laid along the central load-bearing wall, on which vertical racks rest. Lying is used when installing layered rafters, when the run between the outer walls is more than 10 m.

The crate is a board or timber stuffed on the rafters. The crate is solid and with gaps, depending on the type of roof. It is always attached perpendicular to the direction of the rafters, most often horizontally.

If there is no more than 10 m between the outer walls and there is no load-bearing wall in the middle, arrange hanging rafter system. With such a system, the upper ends of adjacent rafters are sawn at an angle and connected to each other with nails, excluding the installation of racks and ridge timber. The lower ends of the rafter legs rest on the outer walls. Due to the lack of racks, the attic space can be used to equip the attic. Very often, floor beams perform the function of puffs. To strengthen the structure, it is recommended to install the upper puff at a distance of 50 cm from the ridge.

In the presence of a central supporting wall, the arrangement is more justified layered truss system. A bed is laid on the wall, support posts are attached to it, and a ridge beam is nailed to the posts. This installation method is quite economical and easier to perform. If the ceilings in the interior are designed at different levels, the racks are replaced with a brick wall dividing the attic into two halves.

The installation process of the roof includes several stages: attaching the Mauerlat to the walls, assembling the truss trusses, installing the rafters on the floors, installing the ridge, and attaching the batten. All wooden elements before assembly are carefully treated with any antiseptic composition and dried in the air.

For work you will need:

• timber 100x10 mm and 150x150 mm;
• boards 50x150 mm;
• boards 30 mm thick for lathing;
• ruberoid;
• metal studs;
• jigsaw and hacksaw;
• a hammer;
• nails and screws;
• square and building level.

in wooden houses Mauerlat functions are performed by logs of the last row, which greatly simplifies the workflow. To install the rafters, it is enough to cut grooves of the appropriate size on the inside of the logs.

in brick houses or buildings from blocks, the installation of the Mauerlat is as follows:

Mauerlat bars should form a regular rectangle and be in the same horizontal plane. This will facilitate further installation of the roof and provide the structure with the necessary stability. In conclusion, markings are made on the bars for the rafters and grooves are cut along the thickness of the bar.

When choosing a hanging truss system, it is necessary to assemble the trusses on the ground, and then install them above the floors. First you need to draw up a drawing and calculate the length of the rafter legs and the angle of their connection. Typically, the roof slope is 35-40 degrees, but in open, heavily ventilated areas, it is reduced to 15-20 degrees. To find out at what angle to connect the rafters, you should multiply the angle of the roof by 2.

Knowing the length of the run between the outer walls and the angle of connection of the rafters, you can calculate the length of the rafter legs. Most often, it is 4-6 m, taking into account the cornice overhang 50-60 cm wide.

The upper ends of the rafters can be fastened in several ways: overlap, butt and "in the paw", that is, with cut grooves. For fixing use metal pads or bolts. Next, the lower and upper puffs are mounted, and then the finished trusses are lifted up and installed above the ceilings.

The extreme trusses are attached first: with the help of a plumb line, the rafters are set vertically, the length of the overhang is adjusted and attached to the Mauerlat with bolts or steel plates. So that during the installation process the farm does not move, it is strengthened with temporary jibs from a bar. After installing the extreme rafters, the rest are exposed, keeping the same distance between them. When all the trusses are fixed, they take a board with a section of 50x150 mm, the length of which is 20-30 cm longer than the length of the eaves, and nail it along the upper edge of the slope. Do the same on the other side of the roof.

The first option: on the rafter leg, at the place of contact with the Mauerlat, a rectangular groove is cut out 1/3 of the beam width. Stepping back from the top of the box 15 cm, a steel crutch is driven into the wall. The rafter is leveled, the grooves are aligned, then a wire clamp is thrown on top and the beam is pulled close to the wall. The ends of the wire are securely fixed on the crutch. The lower edges of the rafters are carefully cut with a circular saw, leaving an overhang of 50 cm.

The second option: the upper rows of walls are laid out with a stepped brick cornice, and the Mauerlat is placed flush with the inner surface of the wall and a groove is cut in it for the rafter. The edge of the rafter leg is cut at the level of the upper corner of the eaves. This method is simpler than the others, but the overhang is too narrow.

The third option: ceiling beams are extended beyond the edge of the outer wall by 40-50 cm, and roof trusses are installed on the beams. The ends of the rafter legs are cut at an angle and rest against the beams, fixing with metal plates and bolts. This method allows you to slightly increase the width of the attic.

The device of layered rafters

1 shows the cutting of the struts of the rafters into a bed laid on intermediate supports, and in Fig. 2 - supporting the rafter leg on the Mauerlat

The procedure for installing a layered truss system:

When the main elements are fixed, the surface of the rafters is treated with flame retardants. Now you can start making the crate.

A beam of 50x50 mm is suitable for the crate, as well as boards with a thickness of 3-4 cm and a width of 12 cm or more. Waterproofing material is usually laid under the crate to protect the truss system from getting wet. The waterproofing film is laid in horizontal stripes from the eaves to the roof ridge. The material spreads with an overlap of 10-15 cm, after which the joints are fastened with adhesive tape. The bottom edges of the film must completely cover the ends of the rafters.

It is necessary to leave a ventilation gap between the boards and the film, so first wooden slats 3-4 cm thick are stuffed onto the film, placing them along the rafters.

The next stage is the sheathing of the truss system with boards; they are stuffed perpendicular to the rails, starting from the roof eaves. The step of the lathing is affected not only by the type of roofing, but also by the angle of inclination of the slopes: the larger the angle, the greater the distance between the boards.

After the installation of the battens is completed, they begin to sheath the gables and overhangs. You can close the gables with boards, plastic panels, clapboard, waterproof plywood or corrugated board - it all depends on financial capabilities and personal preferences. Sheathing is attached to the side of the rafters, nails or self-tapping screws are used as fasteners. Overhangs are also hemmed with various materials - from wood to siding.

Video - Do-it-yourself gable roof

To install a gable roof yourself, average carpentry skills and an understanding of its manufacturing technology are enough. All this is easy to understand. It is also necessary to involve an intelligent assistant in the process, because many operations cannot be performed by one person alone. Therefore, many without a doubt take up this work and successfully cope with it.

Do-it-yourself gable roof device

The construction of a country house is associated with considerable costs. Therefore, many people are looking for options to reduce the cost of this process through the use of modern materials and technologies. Currently, frame buildings with gable roofs have become very popular. This happens largely for the reason that even a person with minimal knowledge of the construction business, with appropriate preliminary preparation, can carry out such a design.

A gable roof is formed by triangular trusses connected to each other by a longitudinal upper beam (ridge run) and a crate

However, the construction of the roof is a crucial moment that requires a serious attitude. Need to calculate:

• correct angle of inclination;
• rafter length;
• the distance between them;
• ways to connect different parts to each other.

Without experience in the production of such work, you should not take on complex structures, but it is quite possible to build a small house with a simple gable roof with your own hands.

Design features of gable roofs

Such a roof consists of two inclined planes located at a certain angle. Gables are arranged along the end walls, which are a vertical continuation of the walls. In shape, they are isosceles or arbitrary triangles, if the slopes are arranged at different angles to the horizontal. In the case of a gable sloping roof, the gables are trapezoid-shaped.

When building a roof, a rafter system is created, which is the supporting element of the roofing pie. The rafter system can be made in the form of hanging rafters if there are no capital partitions inside the building box. If available, a floor frame is arranged when the span is supported by three or more points.

How to make a gable roof yourself

Depending on the design of the truss system, its main elements may be different, but the main details are present in all options:

1. Rafters are the main load-bearing element of the structure, on which roofing material is mounted through the crate.
2. The ridge run - also called the spinal beam, combines all the rafter legs into a single whole, evenly distributes the load on the Mauerlat.
3. Rack - used in floor structures as an additional support on a major internal partition.
4. Lying - a horizontal bar on which the racks rest, serves to evenly distribute the loads on the Mauerlat.
5. Mauerlat - a support beam between the walls and the upper structure of the building, intended for attaching rafters.
6. Sheathing - flooring from a board 25 millimeters thick for fixing the roof finish.

Roof design

In the process of designing the truss system, it is necessary to optimally place all the elements of the frame in order to ensure a uniform load on the roof over its entire area. The main types of load are:

1. Snowy - occurs under the action of a layer of snow lingering on the roof. At high rates for the construction region, the angle of inclination of the roof is increased so that the snow comes off it as it accumulates.
2. Wind - associated with the force of the impact of the wind. In open, blown places, it is higher. The means of counteracting wind loads is to reduce the angle of inclination of the roof.

Thus, it is necessary to find the optimal combination of these indicators with simultaneous exposure to wind and snow. Data on specific loads for the construction region can be found on the Internet.

Gable roofs with a simple design give the house an elegant and festive look.

Photo gallery: projects of houses with gable roofs

The gable roof allows you to arrange a small attic room on the second floor. The slope of the gable roof is selected based on the intensity of the winds and the average snow load in the construction area.

Calculation of the parameters of a gable roof

Determination of the main characteristics of the roof is necessary already at the stage of designing the foundation to calculate the effect of the total weight of the building on the support base.

Area calculation

With a symmetrical gable roof, it is enough to determine the area of ​​​​one slope and double the result.

The height of the roof depends on the chosen angle of inclination of the slope. Usually it is in the range of 30-45 degrees. In the first case, the height will be half the distance from the projection of the ridge to the Mauerlat axis. Using the Pythagorean theorem and after doing the calculations, we get that the length of the slope for a building of 10x9 m will be 5.05 meters. The slope area is defined as 5.05 x 10 = 50.5 square meters. And the total roof area will be 50.5 x 2 \u003d 101 m 2.

In cases where a gable roof has a non-equilibrium roof, i.e., the axis of the ridge is offset from the axis of the building, the area of ​​\u200b\u200beach slope separately is calculated using the same method and the results are summarized.

However, this calculation does not take into account the area of ​​the roof overhangs. Usually they are 0.5–0.6 meters. For one slope, the overhang area will be 0.5 x 5.05 x 2 + 0.5 x 10 \u003d 4.1 + 5 \u003d 9.1 m 2.

The total roof area will be 101 + 9.1 x 2 = 119.2 m 2.

Calculation of the section of the rafters

The size of the cross section of the rafters depends on several factors:

• the magnitude of the load on them;
• the type of materials used for rafters: log, timber - homogeneous or glued;
• rafter leg length;
• types of wood;
• the distance between the axes of the rafter legs.

All these parameters have long been calculated, and to determine the cross section of the rafter legs, you can use the data below.

Table: rafter section size

With an increase in the installation step of the rafters, the load on each of them increases, which leads to the need to increase the cross section.

Common sizes of the main parts of the truss system:

Determining the angle of inclination

The angle of inclination of the roof slope is determined by the requirements of its finishing coating:

One of the reasons for reducing the angle of inclination is the desire to make the attic or attic space as large as possible. This intention is also the reason for the installation of a sloping roof.

Calculation of the distance between the rafters

This parameter depends on the type of finish coating, or rather, its weight. For the heaviest material, the distance should be minimal, from 80 centimeters. In the case of using a soft roof that is light in weight, the distance can be increased to 150 centimeters. The calculation of the number of rafters and translations is carried out as follows:

1. The length of the building (10 meters) must be divided by the distance between the rafters, presumably 120 centimeters: 1000 / 120 = 8.3 (pieces). We add 1 to the result, we get 9.3.
2. Since the number of rafters cannot be fractional, the result is rounded up to an integer - 9.
3. The distance between the rafters is finally set: 1000/9 = 111 centimeters.

With this distance, all rafters will be equidistant, and the load from the roof will be distributed evenly.

The length of the rafters is calculated according to the Pythagorean theorem, as already shown above.

Do-it-yourself installation of a gable roof

Work on the installation of the truss system begins with the installation of the Mauerlat.

Mounting the carrier on the wall

Mauerlat is made from high strength wood - oak, larch, etc. In the absence of such materials, pine can be used.

The bar is of standard length - 4 or 6 meters. Therefore, the connection of several parts along the length is inevitable. It is made with a gash of the connected ends “half a tree”, for example, for a bar with a section of 150x150 millimeters, a sample of 75x150 with a length of 300 mm is made. The ends are overlapped. Fastening is carried out with two or four screws M12 or M14 with the installation of washers of large diameter. By the same principle, the bars are connected at the corners. The finished structure is a regular rectangle, which is installed on the upper plane of the wall around the perimeter.

The Mauerlat installation technology provides for its placement strictly along the axis of the wall or with an offset in any direction. In this case, you can not place the support beam closer than 5 centimeters from the edge. To increase the service life, the Mauerlat should be installed with waterproofing on the wall surface. Most often, ruberoid is used for this.

Methods for attaching the Mauerlat to the wall

1. Anchor bolt installation. Ideal for monolithic walls. Threaded studs are immured into the wall when it is cast.
2. Wood dowels. They are hammered into the drilled hole. With such fixation, additional metal fasteners are used.
3. Forged staples. They are used with pre-installed embedded parts made of wood.
4. Stud or armature. The pins are immured during the laying of the wall and are removed through the support beam through the drilled holes. The diameter of the fasteners should be 12–14 millimeters, the protrusion above the surface of the timber should be 10–14 centimeters.
5. Steel wire. A bundle of two or four wire strands is installed when laying the wall 2–3 rows before its completion. The Mauerlat is tightened using a crowbar. Often used as an additional fastening of the support beam.
6. When constructing a reinforcing belt, fastening to studs or anchor bolts is also used.

The mounting points should be located approximately in the middle between the rafter legs.

Video: installing a Mauerlat on an armored belt

Photo gallery: ways to mount the Mauerlat on the wall

The studs are immured into the wall during its pouring, then a Mauerlat is put on them and fixed with bolts. The wire is also installed at the stage of laying the wall. staples

Types of roof systems and their installation

The choice of roof truss design is determined by the configuration of the building. If there are no internal capital partitions, a hanging truss system is constructed.

In the presence of capital partitions, it is necessary to use a floor mounting scheme.

Manufacturing of truss pairs

This is the name of a pair of rafter legs connected in an arch with the installation of a spacer element in the form of a puff for a hinged system or a crossbar for a flooring system.

Installation of truss pairs is carried out in three ways:

1. Assembly is done at the top after the translations are installed. They are covered with a flooring made of wood, nailed.
2. The formation of truss pairs is performed on the ground in the immediate vicinity of the house. Only blanks are assembled, which are a rigid triangular structure. The lifting of products is carried out when the rafter pairs for the entire system are ready. For this, it is possible to use lifting devices in the form of a manual or powered winch, which presents certain inconveniences and additional costs. On the other hand, assembly on the ground is much easier and more accurate.
3. The assembly of the roof directly at the installation site is carried out in detail.

With any option, the rafter legs are mounted according to the template, which is the first truss. For higher assembly accuracy of the parts of the next pair, it is desirable to fix them to the previous one with clamps.

The procedure for installing the truss system

Prefabricated roof elements are installed in the following sequence:

Fastening parts of the truss system

For reliable connection of the elements of the roof frame, various auxiliary elements are used, made of galvanized steel up to 1.5 mm thick.

When assembling with the use of additional connectors, labor productivity increases and the strength characteristics of the structure increase.

To connect the elements of the roof of wooden buildings, special fasteners are used. So, the upper joint of the rafters is often connected using a hinge. This is due to the frequent movements of the building, including seasonal ones.

For the same purpose, sliding fasteners are used on houses made of this material.

Video: quick rafters

Before installing the crate, the roof is insulated. For this:

1. The inner crate is stuffed from the side of the attic or attic.
2. The vapor barrier film is stretched.
3. The heater is installed.
4. A moisture-proof film or membrane with one-sided permeability is laid.

Thus, in addition to insulation, a ventilation system of the under-roof space is created. It starts to work after the installation of the coating.

Under certain conditions, roof insulation can be done from the inside, it is not so convenient, but you can safely work in all weather conditions. The formation of the roofing cake is carried out in the reverse order. Each layer of insulation as the flooring needs to be strengthened in the openings between the rafters.

Creating a frame gable

Before proceeding with the design of the pediment, you need to arrange the crate and lay the finish coating of the roof.

When forming the crate, the type of future roofing is taken into account. It is made from edged boards with a thickness of 25 millimeters. The crate happens:

1. Solid - boards are stuffed at a distance of 2-4 centimeters from one another. It is applied when using a tile or a soft roof.
2. Sparse - the distance between the boards is 15–25 centimeters. Such a crate is arranged under a metal tile, corrugated board, slate and other similar materials.
3. Rare - the distance between the boards is from 0.6 to 1.2 meters. It is used when the length of the coating sheets is equal to the length of the slope with an overhang. This cover is only made to order.

The crate should be taken out of the gable rafters for the overhang device.

Roofing installation

Before laying the crate, the roof is insulated and a moisture-proof layer is laid. Further:

1. Roof covering is being laid. The installation sequence is from bottom to top in order. The straightness of the first row is controlled by a stretched cord.
2. Roofing sheets are fastened with self-tapping screws using shock-absorbing pads.

When installing the finishing coating of the roof, you cannot save on fasteners; the protective layer must be durable, able to withstand wind and snow loads.

Installation of gables

The crate of the frame gables is made based on the characteristics of the material intended for the front finish. For this, the following products can be used:

After installing the crate, it is necessary to lay a moisture protection from a polyethylene film 200 microns thick. It can be fixed with building brackets. This work is done outside. On the film, you can sheathe the outer surface with the selected finishing material.

Gables need to be insulated with rolled or tiled heaters. The thickness of the protective layer should be at least 10 cm, and for areas with a cold climate - at least 15 cm. An internal moisture-proof film layer is stretched over the insulation.

On top of it, a crate for the front finish is stuffed, for which bars measuring 50x50 millimeters are used. Finishing of the entire building is carried out simultaneously, after the insulation of the roof.

In the process of facing the pediment, windows are installed if they are provided for by the project, and in some cases doors.

Registration of overhangs

Roof overhangs, both gable and cornice, except for a purely decorative function, are designed to protect walls and foundations from water or snow. Their sizes are usually 50-60 centimeters. Overhangs are made with various materials:

• planed board, installed end-to-end or overlapped;
• grooved lining;
• lining block house;
• sheet plastic;
• sheet profiled or smooth metal;
• finished products made of metal or plastic - soffits.

There are several ways to arrange overhangs:

Ventilation holes must be made along the lining. They can be of any size, but large ones must be covered with a fine mesh of any material. This avoids the penetration of birds and harmful insects into the under-roof space. Soffits are sold with ready-made ventilation grilles.

Ventilation is arranged only on cornice overhangs; it is not needed for gable ledges.

Video: do-it-yourself gable roof device

With the modern abundance of building materials and their quality, you can install a gable roof yourself. The cost savings will be quite significant. But it can also turn into losses if you do not carefully consider every step you take during construction. I wish you success!

More and more people are striving to realize their innermost dream - to get out of the high-rise urban development in their own home. Acquired suburban area quickly turns into a construction site. And, in accordance with the natural mentality of most Russian men, the construction of a new home is very often carried out on their own. And, many of the amateur craftsmen do not have much experience in this area at all, they learn literally on the go, they are looking for useful and reliable information in available sources, including on the pages Internet resources dedicated to construction. We hope that our portal will provide them with serious assistance in this matter.

So, after the walls of the house are raised on a reliable foundation, it is necessary, without delaying this, to proceed to the creation of a roof and roofing flooring. There can be many options here. And one of the most commonly used is a gable roof structure. It is not as complicated in calculations and installation as some others, that is, even a novice builder should cope with it. Therefore, the topic of this publication is the construction of the roof of a private house with your own hands using the example of a gable truss system with

It should immediately be noted that the article does not give a ready-made "recipe". The goal is to demonstrate the principles of calculating a gable roof and the sequence of its construction. And a master with an appropriate estimate should already bring the recommendations received to his own, specific construction conditions.

General information about the design of gable roofs

The basic design principle of a gable roof is probably clear from its name. The roof of such a roof forms two planes converging along the ridge line and resting on the long walls of the house (along the cornice lines). From the end sides, the roof is limited by vertical gable walls. As a rule, both along the line of cornices and along the pediment, the roofing is somewhat released outside, outside the building in plan, so that overhangs are formed that protect the walls from direct precipitation.

Most often, the slopes have a symmetrical shape. Sometimes they resort to asymmetry, when the slopes are located at different angles to the horizon and, accordingly, differ in their length. But these are isolated cases, and will not be considered in this publication.

The height of the roof in the ridge, that is, the steepness of the slopes, can be different - it all depends on the planned use of the attic, the architectural ideas of the owners, and the type of roofing used.

Gable roofs have proven their high reliability. And the relative simplicity of the design makes them so popular among private developers.

The external similarity of gable roofs does not at all mean the uniformity of the design of their truss systems. It is precisely in this matter that there can be significant differences, depending both on the size of the building and on its design features.

According to the principle of structure, the truss systems of gable roofs can be divided into two groups:

• If the rafters rest on the outer walls of the building and are interconnected in a ridge knot, then such a system is called a hanging system.

To give additional rigidity to such a design, the rafter legs of each pair are reinforced with horizontal puffs (contractions). Vertical racks supported by floor beams, or diagonally mounted struts can also be used.

• In the case when the design of the house assumes the presence of a main wall inside the building, a layered truss system is often used. The name speaks for itself - the legs "lean" on the racks, which, in turn, rest on a bed laid along upper end of the capital internal walls. And, this wall can be located both in the center and offset from it. and for large buildings, two internal walls can also be used as supports. Several examples of layered systems are shown in the illustration below.

• However, a kind of "hybrid" of both systems is often used. The rafters in these cases, even without the presence of an internal partition, also receive support on the central post in the ridge assembly, which, in turn, rests on powerful floor beams or on horizontal puffs between the rafter legs.

In any of the systems, especially in cases where the rafter legs are of considerable length, additional reinforcement elements are used. This is necessary to exclude the possibility of deflection of the beam or even its fracture under the action of loads. And the loads here will be considerable. First of all, it is static, due to the weight of the rafter system itself, lathing, roofing and its insulation, if it is provided for by the project. Plus, there are large variable loads, among which wind and snow come out on top. Therefore, they strive to provide the necessary number of support points for the rafter legs in order to prevent possible deformation.

Some of their reinforcement elements are shown in the design diagrams of the truss system:

The illustration above shows an example of a layered truss system:

1 - Mauerlat. Usually this is a bar rigidly fixed on the upper end of the outer walls of the building. It serves as a support and base for securing the lower part of the rafter legs.

2 - Lezhen. A bar attached to the internal partition of a building.

3 - Rack (another name is the headstock). Vertical support going from the bed to the ridge run.

4 - Skate run. A beam or board that connects the central posts and serves as the basis for securing the upper ends of the rafter legs.

5 - Rafter legs.

6 - Struts. These are additional reinforcement elements, through which you can reduce the free span of the rafter leg, that is, create additional support points for it.

7 - Lathing, which must match the selected roofing.

Prices for fasteners for rafters

fasteners for rafters

In hanging-type systems, reinforcement is made by installing horizontal puffs (pos. 7), which rigidly connect opposite rafter legs, and thereby reduce the bursting load acting on the walls of the building. There may be several such delays. For example, one is installed at the bottom, closer to the Mauerlat level or even almost flush with it. And the second is closer to the ridge knot (e is often also called a crossbar).

With a large length of rafters, it may also be necessary to use vertical racks (pos. 3) or diagonal struts (pos. 6), and often both of these elements in combination. They can be supported by floor beams (pos. 9), as shown in the illustration.

It should be correctly understood that the shown schemes are not a dogma at all. There are other designs of truss systems. For example, it is often used to fasten the lower part of the rafter legs not to the Mauerlat, but to the floor beams that are extended beyond the walls of the house. Thus, the necessary

In the roofs of large houses, more complex schemes can be used. For example, the rafters are connected by additional longitudinal runs, which, in turn, are supported by vertical posts or struts. But it is hardly reasonable to take on the creation of such complex systems without having well-established experience in this area. Therefore, we confine ourselves to the construction of fairly simple gable roofs.

Carrying out calculations of the parameters of a gable roof

The construction of the truss system and the arrangement of the roof on its basis should always begin with the necessary calculations. What are the tasks involved?

• First of all, it is necessary to deal with the ratio "ridge height - steepness of the roof slopes."
• After that, it will be possible to accurately calculate the length of the rafter legs, both “clean” and full, that is, taking into account the planned cornice overhangs.
• The length of the rafters and the estimated pitch from the installation will make it possible to determine the cross section of the material suitable for their manufacture, taking into account the expected roof loads. Or, on the contrary, based on the available material, choose the optimal step and place additional support points - by installing the reinforcement elements mentioned above.

The listed parameters will allow you to draw up a diagram and a drawing of the truss system as accurately as possible, correctly position all its elements. According to the existing scheme, it will be much easier to calculate how much and what material is required for installation.

• You will need to find out the total area of ​​\u200b\u200bthe roof slopes. This is necessary for the purchase of roofing material, hydro - and vapor barrier membranes, insulation, if thermal insulation of the roof is planned. In addition, the area parameter is also important for determining the amount of material for arranging the lathing for the selected roofing.

To make it clearer during the presentation of the calculation procedure, the main quantities are schematically shown in the illustration below:

D- the width of the house (the size of its gable wall);

VC- the height of the roof in the ridge above the plane of the Mauerlat or floor beams, depending on what the lower ends of the rafter legs will be attached to;

a- the angle of steepness of the roof slopes;

FROM- working length of the rafter leg, from the ridge to the Mauerlat;

∆C- elongation of the rafter leg to form the planned cornice overhang;

W- installation step of the rafter legs.

Let's start with the above questions in order.

The ratio of the steepness of the slopes and the height of the roof ridge

These two quantities are closely related. And tothem calculation can be approached from different angles, taking certain criteria as initial ones.

• For example, the owners see their house with a high roof, something remotely reminiscent of the Gothic style of architecture. It is clear that with this approach, the height of the roof in the ridge increases sharply and, accordingly, the steepness of the slopes. True, it should not be forgotten that such roofs experience maximum wind loads, due to their pronounced “sail”. But the snow on such slopes will practically not linger. So it is worth considering these two factors initially. Perhaps, for an area closed from the winds, but with a predominance of snowy winters, this option will generally be the most acceptable.

But do not forget that the longer the rafter legs, the more difficult the system itself will be in arranging, which will require a lot of reinforcing parts.

• Another consideration to make the roof higher very often becomes the desire to have a functional attic space, up to equipping it with a full-fledged living room.

For an attic room, of course, a broken truss system is preferable. But if, nevertheless, a gable is planned, then a lot of space is eaten up by corner zones along the line connecting the rafters with a Mauerlat. It is necessary to increase the steepness of the slopes (see above).

True, and here there may be an acceptable solution. For example, the Mauerlat is not located at the level of the ceiling, as in the "classic" version, but on the side walls, which are deliberately raised above the ceiling to a certain height. Then, even with a large steepness of the slopes, and without much complication of the design of the system, magnon can achieve very spacious attic rooms.

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metal tile

By the way, it is this option that will be considered below, when the story goes about the installation of the truss system.

• It happens that the owners of the future home, on the contrary, make a decision about the minimum angles of roof slope. This may be due to material saving structures, lack of usable attic space, local conditions such as very windy but not particularly snowy terrain.

True, with this approach, we must not forget that any roofing has certain lower limits for the steepness of the slopes. For example, if it is planned to lay piece tiles, then it is necessary to ensure a steepness angle of at least 20, and for some models even 30 degrees. So if the plans already have one or another roofing, its characteristics should be correlated with the height and steepness of the roof.

So, how is the calculation carried out. As a constant value - a constant, we have the width of the house along the gable wall ( D). Using the well-known trigonometric formula, it is easy to find the height ( VC), based on the planned steepness of the slopes (angle a).

Sun \u003d 0.5 × D × tg a

It is clear that half the width of the building is taken to calculate a symmetrical gable roof, that is 0.5 ×D.

One more nuance. When calculating according to this ratio, the height difference between the heights of the ridge point and the Mauerlat plane is taken as the height. That is, the excess over the attic floor is far from always meant - this should be borne in mind.

The above formula is included in the proposed calculator.

Calculator of the ratio of the steepness of the slopes of a gable roof and the height of its ridge

Enter the requested values ​​and click the "Calculate rafter length" button

The height of the ridge above the plane of the Mauerlat Vk, meters

Width of the house along the gable wall D, meters

That's not all.

It has already been mentioned above that in order to form a cornice overhang of the roof, the rafters are often made somewhat longer. How to take into account this "additive" to the "clean" length of the rafter leg?

Again, trigonometry comes to the rescue. Everything turns out quite simply:

ΔС = K /cos a

The same approach is practiced if the cornice overhang is formed by building up the rafters with fillies.

The working length of the filly is calculated in exactly the same way. This refers to the release of the filly outside, without a section of its connection with the rafter leg.

In order not to force the reader to look for the values ​​​​of trigonometric functions, a calculator is placed below:

Calculator for calculating the lengthening of the rafter leg to create an eaves roof overhang

Specify the requested data and click the button "Calculate the elongation of the rafter (working length of the filly)"

Planned width of the cornice overhang K, meters

The value of the steepness of the slope a, degrees

Now it remains only to sum up the "clean" length of the rafter leg and its extension to the overhang - this is easy to do even in your mind.

The resulting value will become a guideline when purchasing the necessary lumber and cutting blanks. It is clear that during installation, the rafters are not immediately cut to the exact size - it is easier after installation to trim the ends protruding on the overhangs to the required length. Therefore, either the board is usually taken longer by about 200 ÷ 300 mm.

By the way, the option is not excluded that the resulting total length of the rafters will exceed the standard sizes of lumber can be purchased locally. This means that you will have to build up the rafters - you must also be prepared for this in advance.

Calculation of loads falling on the roof, selection of the optimal section and arrangement of rafters

This stage of preliminary calculations can be considered the most important and difficult. It is necessary to determine what loads the roof structure has to cope with. This will, in turn, make it possible to correctly select the section of lumber for the rafter legs, find the optimal step for their installation, find out whether reinforcement elements will be needed to reduce the free spans of the rafters by installing additional support points.

The total load on the truss system, as mentioned above, consists of several quantities. Let's deal with them one by one.

• Static weight loads are the mass of the truss system itself, the roof covering with the corresponding lathing, and if the roof is insulated, then also the weight of the thermal insulation material. For various roofs, their average statistical indicators of this load, expressed in kilograms per square meter, are characteristic. It is clear that the specific gravity, for example, of a roof covered with ondulin, cannot be compared with roofing their natural ceramic tiles.

Such indicators are easy to find on the Internet. But below will be offered an online calculator that already takes into account all these averages. In addition, a certain margin of safety is already included in this indicator. Such a reserve is necessary, for example, to move a person on the roof, performing certain repairs or cleaning slopes

• But the static pressure of snow drifts is precisely the next factor of external influence on the roof structure. And it's impossible to ignore it. In many areas of our country, due to their climatic features, this criterion for assessing strength becomes almost decisive.

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snow retainers

— Climatic features of the region. AT as a result of long multi-year meteorological observations, experts developed zoning of the country's territory according to the average level of winter precipitation. And, accordingly, according to the load exerted by snow masses on building structures. A map of such zoning is shown below:

Quantitative indicators of load for zones on the map are not given. But they are already included in the calculator calculation program - it will be enough just to indicate the zone number for your region of residence.

- The second factor that directly affects the level of snow load is the steepness of the roof slopes. First, as the angle increases, the force application vector also changes. And secondly, on steep slopes, snow lingers less, and at angles of steepness from 60 degrees and above, snow drifts on the roof do not happen in principle.

• Wind forcing will be a little more difficult, as more of the initial criteria are taken into account. But you can also figure it out. The calculation algorithm is somewhat simplified, but gives a result with a sufficient level of accuracy.

First of all, by analogy with the snow load, according to a special map-scheme, it is necessary to determine your zone by the level of wind pressure. The map is shown below:

The average wind pressure indicators for each of the zones are entered into the calculator calculation program.

But that's not all. The level of wind impact on a particular roof depends on a number of other criteria:

- Again, the steepness of the slopes is taken into account. This is easily explained - both the moment of application of force and the area of ​​​​wind action change, since with steep slopes their windage increases, and with too gentle slopes, the action is not excluded. counter-directional, lifting force.

- The total height of the house at the level of the ridge is important - the larger it is, the greater the wind loads will be.

- Any building is characterized by the presence of natural or artificial wind barriers around it. So, it is practiced to subdivide such conditions for the location of the building into three zones. Their evaluation criteria are entered in the corresponding field of the calculator, and it will not be difficult to choose the right option.

But when choosing this option, one more nuance must be taken into account. It is believed that such natural or artificial barriers really affect the level of wind pressure only if they are located at a distance not exceeding thirtyfold house height. For example, for a building 6 meters high, a forest area located, say, 150 meters from it, yes, will be a natural barrier to wind. But if the edge is more than 180 meters away from the house, the area is already considered open to all winds.

All static and dynamic loads are summed up, and the final value becomes decisive for the selection of material for the rafter legs. However, if we operate with the parameter of specific pressure per area, it will not be very convenient. It is better to bring this value to a distributed load on the rafter legs.

Let us explain: the smaller the installation step of the rafter pairs, the less distributed load falls on each linear meter of the rafter itself. And according to this distributed load, the choice of the optimal section of a beam or board going to the manufacture of rafters will take place.

All of the factors listed above that affect the level of load falling on the rafters are included in the calculator's calculation program. That is, it is enough for the user to indicate the requested values ​​\u200b\u200bin the corresponding fields, and get the finished result of exactly the distributed load, that is, per linear meter of the rafter (board). By changing the value of the rafter installation step, you can observe how the result will change and choose the optimal arrangement. And we will need the resulting final value a little lower.

Calculator for calculating the distributed load on the rafter legs

Green lines.

Suppose, after calculations using the proposed calculator, the distributed total load turned out to be 70 kg / running . meter. The nearest value in the table is 75 (of course, rounding up is carried out to ensure a margin). In this column we look for the indicator of the free span of the rafter legs, that is, the maximum distance between the support points. Let it be in our case 5 meters. This means that from the left side of the table you can write out all the values ​​\u200b\u200bof the sections of a beam or board that are guaranteed to withstand such a load without the risk of deformation or fracture. By the way, the values ​​\u200b\u200band for the diameter of the log are also shown, if the rafters will be prepared from round timber.

It is clear that there is scope for choosing the best option. In addition to the change in the pitch of the rafter legs already mentioned above, which, as we remember, leads to a change in the distributed load, you can try, while still on the diagram, to additionally place elements of the system reinforcement, racks or struts to reduce the free span. This also makes it possible to use smaller cross-section lumber.

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Calculating the area of ​​\u200b\u200ba gable roof

We will probably not dwell on this issue in detail. An easier task than determining the total area of ​​​​two symmetrical rectangles is hard to imagine.

The only nuance. At calculation we do not forget that the length of the slope from the ridge to the eaves takes into account the cornice overhang. And the length along the cornice line - taking into account the gable overhangs on both sides of the house. And the rest - everything is simple, the usual multiplication of these spirit quantities among themselves.

How much material is needed for a roof sheathing?

We figured out the size, number and location of the rafter legs and reinforcement elements of the system. They applied it to the drawing diagram, and it will not be difficult to calculate the required amount of materials. But a large number of boards or timber will also be required for the crate under the roofing. How to calculate?

This issue primarily depends on the type of roofing planned for flooring. Secondly, in many cases, especially when using sheet roofing materials, the steepness of the slopes also matters. But since the flooring of the metal tile will be shown as an example in this article, then the calculation of the crate will be made specifically for it.

This is just the kind of coating for which it makes no sense to make a continuous flooring, and the installation step of the batten guides will in no way depend on the angle of the roof slope. It is only important that each of the longitudinal (in the direction along the cornice line) rows of “tiled” modules rests with its “step” looking down on the crossbar of the crate, where it is fastened with the help of roofing screws.

Thus, the step of arranging the guides of the crate depends only on the model of the metal tile itself, that is, on the length of its modules.

In addition, it is recommended to reinforce the sheathing with an additional board at the start and finish sections (along the lines of the cornices and the ridge), and also, without fail, along the valleys on both sides, if they are present in the roof structure.

Boards with a thickness of 25 mm are used for the crate, if the installation step of the rafter pairs does not exceed 600 mm. With a greater distance between adjacent rafters, but not exceeding 800 mm, it will be more reliable to use a board with a thickness of 32 mm. If the step is even larger, then preference should be given to a beam with a thickness of 50 mm, since at such significant distances it is impossible to allow deflection of the guides under external weight and dynamic load.

The calculator below will allow you to quickly and accurately determine the amount of lumber for the crate. And, the result will be shown in terms of volume, in the total linear length of the selected board or beam, and in the number of standard 6-meter boards (bars).

If you have now come close to the issue of choosing the design of the truss system, the first thing you need to decide is how exactly you will transfer the load from the roof to the house. For example, in the classical scheme of the rafter system, the rafters evenly rest with their ends on the walls or Mauerlat, around the entire perimeter or on both sides, depending on what shape the slopes are. But often today the rafters are attached directly to the attic floor beams, and not to the Mauerlat, and this technology has its own valuable advantages.

And how to properly install the roof rafters on the floor beams, what technical solutions exist and how to make such attachment points - we will now tell.

Of course, building a roof with a Mauerlat is more understandable and logical, because. this method has been practiced for a very long time and has been studied, but you need to study the support of rafters on beams, and you will not find so much useful information as provided by our site anywhere.

But when is such a rafter system needed and why such difficulties, you ask? See, the approach is indispensable when:

• the construction site has rather fragile walls and it is difficult to lay a Mauerlat on them;
• the roof is being rebuilt on the old house, and the bed is already old;
• the rafter system is quite complicated and it needs intermediate supports, but there are none inside the house;
• for someone who builds a house, this method in itself seems more acceptable.

And it’s hard to imagine a real mansard roof without rafter support directly on the beams outside the walls:

Convinced? Believe me, this technology has as many advantages as the classical one.

How to create a reliable foundation for rafters?

The first step you need to take is to build a solid foundation for these rafters. For example, if the floor beams do not have any support (at least in the form of an intermediate wall of the house), then the roof trusses on it should be organized only according to the hanging principle. If there is a support, the rafters can be safely supported directly on the beam without any auxiliary elements.

In simple terms, if the beam in the attic floor is installed securely and has its own supports, then rafters can also be installed on it, and if all this is not there, then it makes sense to firmly connect the rafters with the beams themselves and hang them as a single system. Otherwise, before building the roof, you need to support the beams from the inside of the room, for which there are three different construction methods:

• The most simple the classic support consists of a puff, one sub-beam and struts. The puff is suspended in the middle. Such suspension systems are used today most often for large spans.
• Double the support consists of a puff, hangers, two struts and a crossbar, which serves as a spacer between the boards.
• There is even triple a strut, which is a separate three suspension systems, or one double suspension system and one simple. This is already a complex truss system.

Here's what these systems look like:

Ideally, if you can also calculate such beams for deflection and tension, how much they are ready to hold the entire roof on themselves. There are special online calculators and formulas for this, although it will also be enough for your own peace of mind to invite an experienced carpenter.

Methods for connecting rafters with beams

So you have two main paths:

1. Install the floor beams first, mounting them into the walls, thereby creating a layered truss system.
2. Assemble the roof trusses on the ground and raise them to the roof ready, while the lower tightening of the trusses will simultaneously serve as a support-beam for the future attic floor.

Each of these methods has its pros and cons, but different methods of fastening are used - for trusses, metal or wooden plates are usually fastened, and for assembly on the roof, chipping and cutting into a spike.

Hanging rafters: puff and beam in one role

If we are talking about a small construction site, like a garage, a bathhouse or a change house, then it is enough just to make truss trusses on the ground, and only then raise them to the walls of the building, fixing them on special Mauerlat pins. Here, floor beams are an integral part of the trusses themselves, and this is the very case when the puff in the truss also serves as a support for the attic floor.

And here is how it is implemented in practice:

But about the options when the rafters are based on the floor beams, and do not create a single system with them, we will now examine in more detail.

Rafter rafters: support on beams at several points

Here is a modern master class in the construction of a classic attic roof, in which the rafters rest on the floor beams directly on the roof, and do not build trusses on the ground:

Here, the floor beams are no longer part of a single truss truss, but an independent element on which the entire truss system relies. Moreover, the support occurs not only on the sides of the beam, but also along its entire length.

How to install rafter legs on floor beams?

As soon as the floor beams are ready for the installation of rafters on them, proceed to the manufacture of the rest of the structure and the connection of the rafters to the beams.

To connect the rafter leg to the beam, its end is cut off at the right angle, or a more complex cut into spikes is made. Let's look at both of these options.

Joining a rafter to a beam without cutting

You can do without cutting, if you then use fasteners - this is a normal solution. So, to make a simple cut on the rafters, make a template:

• Step 1. Take a building square and attach it to the board.
• Step 2. Mark the cut at the top of the rafter.
• Step 3 Using a wood protractor, draw a parallel line to the first saw across the rafter. This line will help you determine the line from the weight on the edge of the building.

Here's what it looks like in practice:

It is much easier to make such rafters than for cutting. The main thing is to correctly determine the angle of inclination of the roof and the correct place for the future cut:

As a result, in life, such a design looks like this at a gable roof:

Types of cutting the rafter leg into the floor beam

The mounting configuration itself is more dependent on the angle of inclination of the ramp. For example, for steep pitched roofs where there is little snow load, you can use a single tooth fastener. With the single tooth method, additional spikes are often made to help the rafters not move under loads. And under such a spike, you will already need a nest in the beam.

But, for sure, you know that any such places can weaken the beam, and therefore their depth should be no more than 1/4 of the thickness of the beam and no closer than 20 cm from the edge of the beam (so that a chip does not form).

But if you have a roof with a slope of less than 35 degrees, then it makes sense to use a double tooth, because such an attachment allows you to achieve high knot strength. As in the previous version, you can add two spikes.

With this method, each tooth can be either the same depth or different. For example, you can cut the first tooth only 1/3 of the thickness of the support beam, and the second already half:

The bottom line is that two rafter legs in a structure supported by beams are fixed with a puff. But, if the ends of these legs slide, then the integrity of the puff will be quickly broken. To prevent such a slip, it is necessary to insert, or rather, cut the rafter leg into the puff itself with the help of a tooth - with or without a spike.

In the process of cutting the rafters to the end of the puff, you need to move the tooth as far as possible. If you need to strengthen the fastening of such rafters, then use a double tooth. Another point: the teeth themselves can be of different sizes.

And finally, it is desirable to fasten the end of the rafter legs with twisted wire so that the wind cannot tear off such a roof. It is better to take a galvanized wire as a wire, and fasten it with one end to the rafter leg, and with the other end into a crutch, which is previously laid in the wall masonry at a distance of 30-35 cm from the top edge.

Here is a good example of a neat rafter cut for tightening, which at the same time serves as a floor beam already in a hipped roof:

Metal fasteners for such a node are still necessary, because the notch itself cannot hold the rafter legs under load.

Types of fasteners for nodal connections with a beam

Let's look at how to connect the rafters to the floor beam:

One of the most reliable is a bolted connection, which uses a set of bolts, nuts and washers. So, do everything step by step:

• Step 1. At the protruding end of the beam on its back, make a triangular cut so that its hypotenuse is at an angle the same as the angle of the rafters.
• Step 2. At the same angle, file down the lower part of the rafter leg.
• Step 3 Install the rafters with a cut directly on the beam and fix with nails.
• Step 4. Now shoot a through hole for the bolt.
• Step 5. Put on the bolt and fix the assembly with the nut.

Another quite acceptable option is to fix the rafter and the beam with special metal fasteners:

And here is an example of making wooden fasteners for the same node:

If possible, fix such rafters on beams with forged wire on a special anchor that is mounted in the wall.

Additional design "chair" for supporting rafters on beams

Sometimes the installation of rafters on floor beams is a rather complicated undertaking, in which the beams themselves serve as a 100% support for the entire roof, and it is important to do all this as competently as possible.

In order for the rafter itself to turn out to be sufficiently strong and reliable in practice, the so-called “chair” is used as supporting elements. These are the truss details that connect all the elements together, and in the context it really looks like four legs of a stool:

In fact, the “chair” is the struts that support the run to its entire height. Those. such a "chair" usually contains vertical posts, inclined posts and short struts. With its lower end of the rack, the chair cuts into the lower belt of the truss system or lies perpendicularly, or immediately into the floor beams. There are also different types of such chairs, depending on whether they rest on beams or directly on the rafters.

Here is a good example from this series:

And this is already an example of an unusual design of the truss system, in which the rafters themselves rest on the floor beams along and across, and the structure of the so-called support chairs is clearly visible:

Combined system: alternate supporting rafters

Today, such a variant of the roof is also practiced, which consists of several especially strong trusses located at a distance of 3-5 meters from each other, and the gap between them is filled with construction pairs.

In simple terms, several powerful main trusses are installed on the roof, two or three, and they hold the entire run on themselves. And already in the space between the main trusses, ordinary rafters rely on such runs, according to a simpler scheme.

Those. here, not all rafters rest on the floor beams, but only some, and the rest rely on the Mauerlat. Thus, the entire load is wonderfully distributed! And the concept of such a system is simple: the main trusses are made according to the scheme of hanging rafters, and the secondary rafter legs are made according to the principle of layered ones, while relying only on the bed:

In fact, the whole secret of such a combined system is that layered rafters are laid directly on the triangular hinged arches. In such a cunning way, bending stresses completely disappear from the hanging rafters, and only tensile stresses remain. And this suggests that here it is possible to significantly reduce the cross section of the truss elements. In other words, save money!

As you probably guessed, in your case, the way the rafters are supported on the floor beams will depend on what object you are building: a garage, a bathhouse, a country house or a whole country complex. In any case, all these methods have been tested, are actively used today in practice and deserve attention no less than the more familiar use of the classic Mauerlat.

The issue of the strength of the roofing system is always given the closest attention, because much will depend on this stage of construction. For example: the protection of the home from the environment, adverse weather conditions. And the mistakes made in the organization of such an important factor as fastening the rafters to the floor beams threaten with various troubles, from unplanned repairs to the dismantling of the roof with the construction of an alternative frame. Rafters and floor beams are indispensable segments of the roof system design. Usually, wood is used in their manufacture. And they are also attached in various ways, which we will talk about in today's article.

Roof truss system: one of the possible options

But first, just a few words about the features of the rafter systems - after all, they are also different, and it directly depends on how to attach the rafters to the beams. When designing a structure, they usually choose the most suitable option in a particular case. There are rafters:

1. hanging,
2. layered.

The first type of segments are taken for the construction of light roofs of a rather large area. They will be supported by the walls of the building. The system with the second type of rafters is more complicated, in which the rafter legs rest on additional points.

• When constructing rafters, the entire structure can be based on the Mauerlat. This method is most popular and effective in the construction of the roof of brick and block dwellings.
• If at the top of the walls there is, for example, a monolith - a concrete beam, or the walls of the building are made of beams (logs), the roof usually rests not on the Mauerlat, but on horizontal floor beams that overlap the building box across.
• Roof structures supported by beams are the simplest variation in the construction of a mansard, lighter roof. In the project, the main thing is to correctly calculate the thickness of both the floor beams and the legs of the rafters, taking into account the possible loads on the entire roof structure. And when carrying out the installation, it is necessary to properly support the rafters in the floor beams. Roofs with supports of the rafter system on the overlapping beams (without the participation of the Mauerlat) can be mounted provided that the walls of the building are able to withstand fairly large loads at the points of application.

It should be additionally noted that the correct choice of the rafter installation option, as well as the maximum observance of architecture technologies, will optimally guarantee the absence of the risk of damage to all attachment points of the rafters to the beams, in particular, the roof as a whole.

Mounting technique

In the current conditions, several variations of attaching rafters to the walls of buildings are practiced.

• Using Mauerlats.
• To the beams (floor).
• Drawstring construction.
• Fastening with a crown at the top during the construction of log cabins from beams.
• The upper strapping system for a building that is being built using frame technologies.

Fastener parts

For the installation of truss systems, wooden, as well as metal parts are used. The first include: a bar, a triangle and a dowel, the like. Metal in fastener details is quite widely represented: nails, angle, bolts and screws, clamps and brackets. As well as special devices for installing rafters, which are called "sleds".

Fasteners of this kind are used during installation work on the load-bearing floor beams, during the construction of buildings made of wood. Their main advantages: no cutting into the beams themselves is required, and fastening is carried out using bolts with large nails.

Mauerlat

A popular method of fixing truss systems at the bottom is considered to be a connection with a Mauerlat. But, despite the distribution, in order to perform this work efficiently, you need to know some of the nuances. After all, if something goes wrong, it can affect the reliability and life of the entire roof.

• Before fastening the rafters to the Mauerlat, special cuts must be made from the bottom of the rafter legs. It is not recommended to install the structure without them, since in the load the edge of the bar will slide off the smooth coating of the beam.
• As for the recesses in the Mauerlat itself (it’s not worth making them or not), it may depend on the materials from which it is made.
• In the case of using hardwood, experienced craftsmen advise making an incision in the Mauerlat beam - together with the cut of the rafter leg, it will reliably create a “point-blank” lock. And when you use a coniferous Mauerlat, it is undesirable to make a slot - it will lead to a possible relaxation for the entire arrangement.
• The reliability of the roof under various weather conditions may depend on the method of fastening the rafters with the Mauerlat.

How to fasten with Mauerlat

Connection: rafter leg + beam

Any roof under the influence of various types of load on it tends to “float” to the sides and down. In order not to bring to this, various methods are applicable that will prevent the displacement of the segments of the truss systems.

Support scheme

One of the methods tested by time and experience of the masters is cutting out connectors in the rafter legs, which will be possible by connecting with a tooth with an emphasis, with a spike, or by supporting the rafters on the beam ceiling.

The cut in the first variant is used if the roof has a large sloped angle. This means that the rafters are attached at an angle of more than 35 o. A tooth is made in the rafter leg with an emphasis and with a spike, and in the body of the beam a corresponding nest is made under the spike (deepening of the tie-in to one third of the thickness of the timber itself, otherwise the structure will be weakened). The cut is carried out, retreating from the edge to a distance of no more than 40 cm, in which case it is usually possible to avoid chipping. And in order to prevent the joints from slipping sideways, a single tooth is created together with a spike.

Cuttings with 2 "teeth" can be used for a sloping roof, in the case when the angle between the connected elements will not exceed 35 °. The process itself is implemented by one of the following methods:

• in 2 spikes;
• in the stops - without the participation of spikes;
• in stops, complemented by spikes;
• fastening of the lock plan with 2 spikes (other variations are possible).

For 2 teeth, the entrance is usually the same in depth. However, in some cases, the 1st of the teeth supplemented with spikes is deepened by a third of the thickness of the entire beam, and the 2nd by half.

When arranging roof structures, the technique can also be used when they are connected to each other: a rafter leg plus a ceiling beam from the floor (it is used quite infrequently). In this case, a persistent tooth is constructed in the leg in such a way that the 1st of the planes fits on a flat beam cut, and the 2nd is fixed in a cutout, which is buried in a third of the thickness of the beam. For greater strength, in addition to the cuts, an additional connection is often also made with the help of bolts and clamps.

Types with tightening

On a skate

Modern masters in the construction of roofs use several types of mounts for the rafter system on the ridge:

• butt to butt;
• for the run;
• overlap on the run of the upper skate.

Butt-to-butt connection. At the top, the rafter segment is cut at an angle (which is equal to the planned roof slope). And then they rest against the opposite leg, where circumcision is performed in the same way, but only in an asymmetric direction. It is better to do this according to preliminary templates. In some cases, the cut is performed during installation, and the cut is carried out through 2 beams.

On the run

Run installation similar to the above variation. The differences will be in the installation of the ridge beam itself. This design is highly reliable, but it can not always be abused, since it will require additional installation of support beams. As a result: the attic is not very convenient for further use. This method will allow you to install pairs of rafter legs on the spot, without any preliminary "curtseys" and templates. The upper segments of the legs in this case rest against the ridge beam, and the lower segments against the Mauerlat.

Overlap on the run of the skate. Here, the installation is carried out in the same way as in the previous version, only the upper joints of the rafters are overlapped, touching from above not with the ends, but with their sides. Fasteners in this case will be bolts (as an option - studs).

Calculation principle

At the preparatory stage for construction, it is necessary to pre-calculate the rafters with floor beams. The design of the roof frame takes into account the climatic and other features of a particular region, its characteristic snow and wind load. Based on these data and SNiP, which determine the relative and permissible deflections, the section will be calculated for all elements of the system: roof beams, rafters, and other parts of the farm. It is also required to perform structural calculations that determine the stacking spacing for beams. And the distance between the beams, in turn, determines the step for placing the rafter legs.

As you can see, it is quite possible to build a roof rafter system with your own hands, if you study the whole process step by step: from buying material to determining the load withstand by the building structure and how to attach the rafters to the floor beams.