The device of rafters of a gable roof. Calculation of the truss system of a gable roof. The specifics of hanging truss systems

The erection of the roof is one of the most important stages of construction. The durability of the building itself and the level of comfort of living in it directly depend on the reliability of the "umbrella" from above, on its resistance to precipitation and any external influences.

Of all the variety of roof structures, gable can be attributed to the most popular, simply because of the relative simplicity of its construction. However, behind this "simplicity" lies a lot of different nuances, the need to carry out certain calculations and follow technological rules. However, this publication has the main task: to show that installing the rafters of a gable roof with your own hands is a completely doable task, even for a novice builder.

Let's walk through the process of installing rafters for such a roof together, from the basics of preliminary design to an example of practical implementation.

General arrangement of a gable roof

Basic concepts

Structural elements of the gable roof truss system

Let's make a reservation right away that this scheme, of course, cannot reflect the entire possible variety of designs, but the main parts and assemblies on it are shown quite clearly.

1 - Mauerlat. This is a board or beam that is rigidly attached to the upper end of the external load-bearing walls of the building. Its purpose is to evenly distribute the load from the entire roof system to the walls of the house, creating conditions for reliable fastening of the rafter legs at their lower fulcrum.

2 - rafter legs installed in pairs. They become the main load-bearing parts of the entire roof system - it is the rafters that set the steepness of the slopes, will be the basis for attaching the batten, roofing, and if the roof is planned to be insulated, then the entire thermal insulation "pie".

For the manufacture of rafter legs, high-quality boards or timber are used, and round timber can also be used. About the section of lumber, which will be sufficient to ensure that all possible loads can be guaranteed, will be discussed below.

The rafters may end on the Mauerlat, but more often they go beyond the perimeter of the walls of the house, forming a cornice overhang. However, lighter parts can also be used for this - the so-called "fillies", with which the rafter legs are increased to the required width of the overhang.

To form a cornice overhang, the rafters are extended with “fillies”

3 - skating run. It can be a beam, a board or even a composite structure. The run runs along the entire line of the ridge and serves to securely connect the upper points of the paired rafter legs, connect all rafter pairs in order to impart overall rigidity to the entire roof structure. In various roof options, this run can be rigidly supported by racks, or tied only to the connection node of the rafter legs.

4 - puffs (contractions, crossbars). Horizontal details of the reinforcement of the system, additionally connecting paired rafter legs to each other. Several puffs located at different heights can be used.

5 - floor beams, which will serve as the basis for mounting the floor in the attic and the ceiling from the side of the room.

6 - and this beam simultaneously performs the role of a bed. This is a beam that runs along the entire length of the roof, which is a support for installing additional reinforcement parts for the truss system. The bed can be installed as shown in the figure (like a floor beam), or it can be rigidly laid on a capital partition inside the building.

7 - racks (headstock) - additional vertical supports of the rafter legs, preventing their deflection under the influence of external loads. Racks at the top can rest against the rafters themselves, or against an additional run, longitudinally connecting the rafter legs at a certain height.

8 - braces. Often, with a large length of the rafter legs, their bearing capacity is not enough, and reinforcement only with racks does not provide the necessary strength. In these cases, diagonal reinforcing elements are used, resting on the bed from below, creating an additional point of support for the rafters. The number of struts and the place of their installation can vary in roofs of varying degrees of complexity.

Some differences between hanging and sloping gable roof systems

Gable roofs can be divided into two types of structures - with layered and hanging rafters. In addition, combined systems are widely used, in which both principles of construction are combined. What is the fundamental difference?

Laminated rafter system

This design of the truss system is characterized by the presence of support on the internal capital partition in the building. On the upper end of this partition, a bed is mounted, on which drains are supported, supporting the ridge run. Thus, the rafter legs are “leaned” on a vertical support, which makes the entire system as strong as possible.

This scheme is the most popular because of its reliability and relative ease of implementation. If it is possible to create an additional point of support in the center, then why not take advantage of this? True, if it is planned to place a living space in the attic, then vertical racks can sometimes become a hindrance. However, their presence is also sometimes “beaten up”, using, for example, an internal light partition for mounting.

Depending on the number and placement of internal partitions, the design of the layered truss system may vary. Some examples are shown in the illustration below:

Fragment “a” shows the simplest option, which, by the way, on short rafter lengths (up to 5 meters) may not even have struts shown - a row of central racks under the ridge run is enough

With an increase in the width of the building, the system naturally becomes more complicated, and additional reinforcing elements appear - puffs and struts (fragment "b").

Fragment "c" clearly demonstrates that the internal main wall does not have to be located exactly in the center, under the ridge. Such an option as shown in the illustration is also quite possible, but with the condition that the displacement of the lying relative to the ridge does not exceed one meter.

Finally, fragment "d" shows how the rafter system can be supported in a large building, but with two main partitions inside. The distance between such parallel beds can reach up to a third of the width of the building.

Hanging rafter system

Graphically, this roof scheme can be depicted something like this:

It immediately catches the eye that the rafters rest only on the lower part, and then are connected to each other on the ridge. There is no additional support in the center, that is, the rafter legs seem to “hang”, which predetermines the name of such a system. This feature imposes certain restrictions on the use of hanging rafters - usually such a scheme is practiced with a distance between the bearing walls on which the Mauerlat is fixed, no more than 7 meters. Installed puffs only partially relieve the load from the external walls.

The illustration below shows several options for a hanging system. However, some of them already, rather, can be classified as combined.

Fragment "d" - hanging rafters are interconnected by a screed at the level of the Mauerlat or fixed to a powerful floor beam, forming a triangle with it. There are no other reinforcing parts. A similar scheme is permissible with a distance between walls of up to 6 meters.

Option "g" - for the same size house (up to 6 meters). The puff (bolt) in this case is shifted upwards, and is often used for filing the ceiling of the attic.

Options "e" and "h" are designed for a span between walls up to 9 meters. Multiple puffs may be used (or top puff in combination with bottom floor beam). Another approach is to install racks under the ridge run, by analogy with a layered system. Only as a lower point of support, it is not a bed on the main partition that is used, but the racks are supported by a puff or a floor beam. To call such an option purely “hanging” is already difficult, since here is clearly a combination of parts from both designs.

To an even greater extent, such a combination of two schemes is expressed in the "and" variant, which is designed for large spans, from 9 to 14 meters. Here, in addition to the headstock, diagonal struts are also involved. Often, such trusses are generally assembled on the ground, and only then they are lifted and set in place, connected to each other, thereby forming the entire roof frame.

So, in preparation for the construction of a gable roof, it is necessary to study the principles of the device of a particular system, evaluate their advantages and disadvantages, choose the best one for your conditions and draw up a graphic working diagram. It will be needed both when purchasing the necessary material, and for the production of the installation work itself. However, drawing up a drawing should still be preceded by some calculations.

Calculation of the basic parameters of the gable roof truss system

Let's take another look at the concept of a gable roof device to highlight those parameters that need to be calculated.

So, in the process of calculation, we need to decide on the following values.

The initial data is the length of the side of the house along the gable part (highlighted in blue - F), and the length of the house along the ridge (purple - D). It is assumed that the owners have already decided on the type of roofing in advance - since there will be certain restrictions on the steepness of the roof slopes. (angle a).

The height of the ridge above the plane of the Mauerlat (H - green), or, conversely, determine the angle of the slope, starting from the planned height of the ridge.
The length of the rafter leg (blue color - L), and, if necessary, the extension of the rafter to form a cornice overhang of the required width (l).
Calculate the total loads that fall on the truss system in order to determine the optimal cross-section of lumber for the manufacture of rafters, their installation step (red - S) and the allowable span length between the support points. All these parameters are closely interconnected.
When these calculated values \u200b\u200bare on hand, it is already easy to draw up a graphic diagram, determine the need and optimal arrangement of reinforcement elements, and calculate the amount of material for their manufacture.

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chainsaw

We calculate the steepness of the slope and the height of the ridge

The slope angle of the slopes can be determined by the owners according to various evaluation criteria:

For purely aesthetic reasons - when the appearance of the building becomes "at the forefront". Many people like roofs with a high ridge, but at the same time, one must not forget that the wind load increases sharply on such a roof. Yes, and materials for the manufacture of a high roof will go immeasurably more. At the same time, on steep slopes, the snow load is reduced to almost zero - it is possible that for the “snowy” regions this assessment parameter may become decisive.
For reasons of useful use of the attic space. With a gable roof scheme, in order to achieve the maximum attic area, it is necessary to build slopes with a very steep slope, that is, with the same consequences as mentioned above.

Finally, there may be a completely opposite approach - for reasons of economy, make a roof structure with a minimum height in the ridge. But in this case, you will have to focus on the minimum allowable slope angles for a particular type of roofing. To reduce the steepness below the indicators recommended by the manufacturer is to “plant a bomb” in your roof, both for reasons of its strength and durability, and from the standpoint of the waterproofing qualities of the coating.

It is not difficult to calculate the height of the ridge above the floor plane (Mauerlat). At the heart of the vast majority of nodes of any roofing system is a triangle, which, in turn, obeys strict geometric (more precisely, trigonometric) laws.

So, in our case, the width of the roof along the gable line is known. If the roof is symmetrical, then the ridge will be located exactly in the middle, and for calculations, you can simply divide the width F by two (the base of the triangle f=F/2). With asymmetrical slopes, you will have to project the top of the ridge onto line F, and measure the distances f1 and f2 from it to the edge of the triangle (to the Mauerlat) on each side. Naturally, in this case, the slope of the slopes will be different.

H =f × tga

In order not to force the reader to look for the values of tangents and carry out calculations manually, a calculator is placed below, in which the necessary tabular values \u200b\u200bare already entered.

In this article I will try to describe in detail how a gable is being built. This form is practically the simplest, suitable for a private house and its construction, from the point of view of monetary costs, is more profitable compared to other more complex roof configurations.

- in the second case, the rafters lie on the floor beams of the floor below. A gable roof made according to this option will be described here.

Let's take a brick box at home as an example. Its dimensions are 8x8 meters, height 3 meters. Do-it-yourself construction of any roof begins with the installation of a maurlat (Fig. 1). Methods for attaching it to the walls were described in the article, which you can read.

Mauerlat is installed flush with the inner surface of the walls. Outside, it must be bricked up so that it cannot be seen. At the same time, the upper surface of the Mauerlat should be 2-3 cm higher than the upper surface of the facing brick, so that the entire load from the roof is transferred only to the Mauerlat. No need to load .

Next, install the floor beams. We do this in the sequence indicated in Fig. 2. First of all, we put the beams indicated by the numbers 1,2,3,4. Their removal determines the width of the eaves. We usually take it from 40 to 50 cm at the request of the customer. As beams, we use a beam, the section of which is determined by making a simple calculation described in detail. In our case, it will be a beam of 100x200 mm.

After fixing the extreme floor beams, we stretch the cord along the upper plane and expose the rest of the beams, if necessary, pulling up the Mauerlat under them, or vice versa, laying thin plywood (you just often order a beam 200 mm high, and they bring it from 190 to 210 mm, this is on our sawmills equipment). We choose their step taking into account the step of future rafters. When using floorboards 50x150 mm as rafters, we take a step of 60-70 cm (it is better to take 60 cm, because roofing insulation has such a width).

Having installed all the long beams, we put the short ones (Fig. 2). Their step is enough to make about 1 meter. This scheme is slightly different from what we are used to seeing in similar pictures. We came to it after the pediment tide sagged on one of our first roofs, although the tides of the tide were securely fixed. In this scheme, the possibility of sagging is completely excluded.

We fasten all beams to the Mauerlat with 150 nails, you can also use metal rafter corners and self-tapping screws. In general, the use of various fasteners for rafter connections makes it easier to work. This is especially convenient for an inexperienced person, you do not need to make complex cuts and notches. We have already talked about this in the article "".

After installing all the beams, we lay (without fixing) boards on them, you can floor, you can inches. They are needed just to walk on them calmly. In order not to clutter up the drawing, I did not show them on it. The next step is to install the ridge beam.

First of all, we set the racks from the board 50x150 mm according to the level or plumb and fasten them with the help of temporary struts. On fig. The 3 spacers are shown on only one post, again to keep the drawing clear. The step of the racks is not more than 3 meters. First we put the extreme ones, then, pulling the laces between them, we put the intermediate racks. After the construction of the entire truss truss, the intermediate racks can be removed and the living rooms can be easily made on the second floor.

The height of the racks is selected depending on what shape of the roof you want to get. I usually advise customers to take it equal to the height of the first floor along the facade (the distance from ground level to the Mauerlat). This proportion is also shown in the figures.

Having installed the racks, we put them on them and fix the ridge beam literally on a couple of screws. As it we use a board 50x200 mm (in principle, 50x150 mm is also possible).

Now we move on to the installation of rafters. First we need to make a template from a 25x150 board. To do this, we apply it to the end of the ridge beam and to the beam (Fig. 4) and draw two lines. Having sawed off a board on them, we get a rafter template.

Of course, it is very good when the foot of the house is laid out with high geometric accuracy and floor beams are also installed. Then we can cut all the rafters at once according to the template and install them calmly. But to be honest, this is quite difficult to achieve, and even more difficult when a new roof is being made on an old house.

In this case, we first make only the top notch at the rafter according to the template. Then we take the resulting workpiece, apply it to the desired beam and mark the bottom gash, as they say in place. All rafters are installed in this way (Fig. 5). Please note that having installed one rafter, we immediately set the opposite one to it in order to quickly remove the lateral load on the ridge beam (otherwise it will bend it).

When the length of the roof slope is large and the standard 6-meter board is not enough, there are two ways to go. The first (I think it is preferable) is to order longer boards at the sawmill. Of course it will cost more. For example, at the end of autumn 2012, we had 1 cube of 6-meter boards cost about 5,500 rubles, and 1 cube of boards 7.5 meters long cost 7,000. But installing rafters is easier and faster than using the second method.

According to the second method, you need to splice two boards. This can be done by sewing on them a piece of board of the same section with a length of 1.5 - 2 meters. See the figure for how this is done. The joint is best done at the bottom, and under it it is necessary to install an additional rack.

We attach the rafter to the ridge beam with two or three nails. For fastening to the floor beam, we have recently been using metal mounting plates and self-tapping screws and adding a couple of nails. Sometimes we use brackets. By the way, I have seen many times how people use staples, but they do it wrong. The bracket must work in tension. Below on the left photo - how not to do it, on the right - how to do it.

Having strengthened the truss truss, we begin to deal with gables. First, we put additional racks, which will be the gable frame (Fig. 7). The accuracy of the installation is controlled by a cord stretched along the bottom of the rafters. Then we make a window opening (Fig. 8). You can make it any size and configuration you like. Please note that in the figure, the stand in the center of the window (supporting the ridge beam at the beginning) was simply cut. It no longer bears almost any load. Having finished with the frame, we sheathe the pediment with an inch (for example, 25x150 mm) (Fig. 9).

The next step is filing the cornice boards around the entire perimeter of the house. The frontal board (sewn to the ends of the floor beams) is made from a board 25x200 mm. We hem two belts from the board 25x100 from below to the cornices (Fig. 10). They are more than enough to fix the soffit in the exterior.

Now, if we are going to mount the drainage system and use metal holders for the gutters, they need to be installed on the stops right now (under the waterproofing film). Moreover, it is also desirable to sheathe the frontal boards with siding at this stage. Then it will not be very convenient to do this. I didn't show it in the picture. In addition, we now only use plastic gutter holders that are attached directly to the front board. It is more convenient with them and you can put them after the roof is assembled.

Next, we proceed to the crate. First of all, using a construction stapler, we fix the first strip of waterproofing film on the rafters (Fig. 11). It is more convenient to work if scaffolding is already installed around the perimeter of the house. In any case, you will have to put them when you make a roof, drain, sheathe the cornices with siding.

Having fixed the film, we nail the slats of the counter-lattice (25x50 mm) to the rafters. The need to use a counter-lattice is described in detail here: . Do not forget to leave room for the overlap of the subsequent waterproofing strip.

Then we make a crate. Now I will not focus on the rules for its installation. This topic is for a separate article. In addition, instructions are attached to any roof covering, which describes in detail how to make a crate specifically for this material (the figures schematically show a crate for a metal tile). I will try to prepare a new article on this topic in the near future.

In this way we cover the entire roof (Fig. 12). After that, it remains only to make a gable overhang and a gable ebb. The sequence here is:

To the protruding ends of the lathing with self-tapping screws, we hem the wind board of the gable overhang (25x150 mm) from below (Fig. 13);

We insert and fix the filly of the gable overhang with self-tapping screws (board 25x150). The distance between them is about 1 meter (Fig. 14);

We sew two belts to the fillies from below (board 25x100). They are also enough to subsequently sheathe the gable overhangs with siding (Fig. 15);

From pieces of the board 50x150 of the required length, we prepare triangular fillies for the gable ebb according to the figure (Fig. 16). Then, fixing them on the takeaways, we also nail two belts (25x100) to them.

This completes our roof. What happened in the end and what happens after the roofing work and sheathing of the gable and cornices with siding is approximately shown in Figures 17 and 18.

The truss system is the roof frame, which is the basis for the roofing decking.

The rafter system is designed to withstand the load of the roof, taking into account natural loads: winds, snow, rain.

The roof option is approved at the design stage.

The purpose of the roof includes several functions: warmth in the house, protection of the premises from natural phenomena, therefore the truss system must be given special attention.

You can read how to calculate the truss system.

It is customary to classify truss systems so that the task of choosing a variant of the future roof is easier to solve:

Shed. The most simple. More suitable for utility rooms, baths, small private houses, gazebos. Provides for the inclined position of the structure at a slight angle (no more than 25°);
gable. Used for small houses and suburban buildings. They look like a triangle, in which the rafters are connected by a beam and are at a certain angle;
Gable broken lines. They have two slopes with a fracture, thanks to which it is possible to increase the area of the attic;
Tri-slope (semi-hip). They have two trapezoidal slopes, which are connected by one end triangular slope (hip);
Four-slope (hip). Used for residential buildings require a significant amount of labor. They have two end triangular slopes and two trapezoidal;
Tent. Used for square buildings. They consist of four triangular slopes, the upper corner of which is connected in the center of the roof;
Multi-forceps. Consist of trapezoidal or other slopes of various shapes, interconnected.

The most suitable designs for - and broken gable. There are others, but they are less common and not as practical as those listed above.

Rafter structures are also classified into:

Hanging. With this type of roof frame due to the lack of load-bearing walls in the room;
Layered. Rafter installation option, providing support on a load-bearing internal wall or support in a building.

The calculation of the material for the roof frame when designing a building is based on the intended configuration and load. Do-it-yourself rafters are not difficult to do, it is important to approach the matter wisely.

Rafter systems of layered and hanging type

Calculation of the load on the rafters

To correctly calculate the load on the rafters, it is necessary to take into account many factors that can affect the severity of the structure.

Important metrics to consider:

Constant load: includes a mass of roofing cake, covering material;
Temporary load: constant and maximum amount of snow, rain, intensity of wind gusts, and in areas with high seismic activity - the effect of storm winds, tornadoes, hurricanes.

In addition, you should keep in mind the mass and strength of the rafter legs, as well as pay attention to the fastening of the gable roof rafters and the installation option.

Scheme of truss systems

The distance between the rafters of a gable roof and the thickness of the rafters

The rafter pitch of a gable roof is the empty space between the rafters. The functionality of the roof depends on the correct calculation of the pitch. As a rule, the step is about a meter.

For a more accurate calculation of the distance between the rafters, there is a certain calculation scheme:

Determine the length of the slope.
The length of the slope is divided by the distance between the rafters.
To determine the number of rafter boards, one is added to the resulting value and rounded up. This determines how many boards are needed per slope.
The length of the slope is divided by the number of boards, get the distance between the rafters.

This calculation is not always final.

Additionally, you should take into account the load of the roofing (its mass), the thickness of the rafters, as well as the dimensions of the rafters for a gable roof.

The thickness of the rafter board largely depends on the covering material:

. Boards are used with a section of 5x20 cm at a step of 60 to 90 cm with a decking of a batten with a section of 4x5 cm;
. Rafter boards - 5x15 cm, step - from 60 cm to 95 cm;
. The cross section of the board is 6x18 cm or 5x15 cm, the distance between the bars is from 80 cm to 130 cm;
. The cross section of the rafter is 5x15 cm, 5x10 cm with a step of 60 cm to 90 cm;
. The cross section of the beam is the same as on the corrugated board with a step of 60-80 cm.

All indicators should be taken into account and the thickness of the rafter should be accurately calculated so that there is no excessive load on the foundation.

Incorrect calculation of the length of the gable roof rafters, as well as incorrect calculation of the pitch indicators, can lead to sagging of the roof.

Do-it-yourself installation of gable roof rafters requires taking into account the weight of the rafter board and all additional structural fasteners.

What is the truss system

Rafter construction - a complex system and installing a gable roof truss system is not an easy task. truss system consists not only of rafter boards, but also of other additional elements:

Mauerlat. An element that distributes the entire load evenly on the supports;
Run. Boards fastening the legs of the rafter: at the top - a ridge, on the side - a side run;
Puffs. Connecting beam, which prevents the divergence of the rafter legs;
Struts, racks. Bars that fix the stability of the rafters, resting on the bed;
. Lattice of bars, which is superimposed perpendicular to the rafters. Transfers the load of the covering material to the truss frame;
. Connecting beam, which serves as a union of roof slopes;
Filly. If the length of the rafter legs is insufficient, they are mounted to form an overhang;
Roof overhang. Goes beyond the bottom line of the slope to prevent precipitation from falling on the walls.

The rafter system implies rafters, stretch marks, braces and racks located in the same plane. They are located in such a way that the main load of the roof structure falls vertically on the external load-bearing walls. Therefore, the manufacture of gable roof rafters is a very important process.

What is the gable roof truss system

Installation of a rafter system with layered rafters

A layered rafter system is used when the span does not exceed 6.5 meters.

In the presence of load-bearing structures inside the building, it is possible to install additional racks.

The main support of the rafter legs is the Mauerlat.

Mauerlat installation

Before mounting the Mauerlat, it is necessary to install an armored belt. It consists of a formwork in which reinforcement is laid and poured with concrete. At the base, with concrete that has not yet hardened, studs are installed, to which the Mauerlat is then attached.

Mauerlat - a beam that is laid on a support (bearing wall) and is the base of the truss frame. A layer of waterproofing material is preliminarily laid. If the length of the beam is not enough for the length of the wall, then it is increased.

Check if the diagonals are equal. A discrepancy of a few centimeters can lead to a frame conversion;
Fix the corners of the Mauerlat;
Attach the Mauerlat with studs or wire. The studs are tightened in two stages, having previously drilled holes for them.

The stability of the roof structure depends on how firmly the Mauerlat is installed.

Therefore, it is necessary to take seriously the fastening of the Mauerlat to the bearing support.

Mauerlat installation

Sill

After the Mauerlat has dried (after 5 days), the installation of the bed is marked on the Mauerlat beam: its axis should be with the same indentation on each side of the Mauerlat beam. The bed is attached to a two-layer waterproofing layer with anchor bolts. To the wall from the inside, the bed should be fixed with twists of wire or staples. Next, markup is made for installing the rafters.

Installation of a gable roof truss system

The anchor points of the layered rafters are the walls and racks inside the frame. The rafters are mounted with hinged attachment points. When using sliders for fastening, a slight lowering of the roof frame is ensured in the first years of the roof's service life.

This installation method is necessary to prevent distortion, as in the early years the building settles a little.

Rafter beams should be fixed either by installing them in prepared grooves and strengthening with fasteners, or by attaching plank linings.

Installation of rafters

ridge knot

The rafters are joined end-to-end, cutting off the edge of the bar so that the angle when connecting opposite beams corresponds to the angle of the slope. Hammer the rafters under the ridge with nails. A variant is possible in which the beams are connected by bolts, a nail or a hairpin, that is, they overlap.

If necessary (if provided by the project), a cut is made in the rafter beams for attaching the ridge beam (purlin).

ridge knot

Racks

Racks are attached with a short span - in the center, on the sides and center - with a wider roof base. Fastening is carried out vertically from the ridge to the inner wall.

Run

Run - a connecting beam for fixing rafter legs. Fastens with bolts or brackets to the rack.

Filly installation

The final step in the installation of the layered system is the installation of filly with a short length of rafter legs for overhang. To install the visor, it is necessary to install additional small rafter boards.

Installation of a rafter system with layered rafters

Do-it-yourself gable roof truss system: installation with hanging rafters

truss system, equipped with hanging rafters, is a triangular structure, where the sides are rafters, and the base is a puff connected to the lower heels of the rafters.

Installation of a hanging-type truss frame can do without installing a Mauerlat: a board that is fixed on a two-layer waterproofing can replace it.

If the structure has a large span, then struts, headstocks, crossbars are attached to it.

Racks in the hanging system are not provided.

Puffs

The puff is the longest beam of the roof frame. To prevent it from sagging, it is necessary to fasten headstock - boards that are attached to the top of the structure on one side, and to the puff - on the other. Fasten with bolts or overlays made of wood. The slack can be adjusted using the threaded collars.

The device of the truss system

Installation of strut beams

The headstock can be supplemented with strut beams, forming a rhombus, where two struts are the lower sides, and the rafters are the upper ones, the upper corner is the ridge. Thus, the struts rest against the headstock, distributing the load.

Strut beams

rafters

Rafters of a hanging structure are mounted like a layered one. When installing attics, the puff is installed closer to the ridge, providing more space under the ceiling. The tightening in this case is fastened by cutting with bolts.

ATTENTION!

When installing a hanging system, a prerequisite for installation is the accuracy of calculations and the strength of the rafters and puffs.

The presence of errors leads to the displacement of the axes of the elements of the system, which provides a distortion of the structure.

How to install rafters for a gable roof will tell you this photo:

Rafter installation

hanging rafters

How to strengthen the rafters of a gable roof

It is necessary to reinforce the rafters of a gable roof when the load calculation is incorrect or frame defects are found.

Strengthening can be done with:

Balok, which are installed in order to transfer the load to them;
Strut mounting with an inclined mount with an emphasis on lying down;
Overlays of double-sided rails;
Increase in the section of the rafter beam in the place of supports on the strut by applying planking from boards with nails or bolts;
board wall, which are attached to the rafters in places where snow is expected to accumulate to increase the bearing capacity of the rafters.

You can resort to strengthening the Mauerlat beam and the base of the rafter beam. Due to high humidity and reduced ventilation, these parts of the frame are more susceptible to decay, therefore, when arranging the roof special attention needs to be paid

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: a rectangular groove is cut out on the rafter leg at the point of contact with the Mauerlat by 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. The 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

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