Types of gable roof truss system: for small and large houses. Do-it-yourself gable roof truss system Gable roof section

truss system- the basis of any roof. The complexity or accessibility of the roof structure depends on the type of roof chosen. Today we will talk about the simplest option - a rafter system for two pitched roof. Experienced specialists tell about the structure of the roof frame, the features and functions of its elements, and how the truss system of a gable roof is made with their own hands.

Gable roof: types and benefits

Recall that a gable roof is a type of roof consisting of two planes (slopes) connected at an angle of a certain degree. It can be simple (symmetrical or asymmetric) and complex - broken.

The rationality of choosing a roof of two slopes is determined by its following advantages:

Profitability and simplicity of erection, in comparison with other roof structures.
Ease and availability of service at any time of the year.
Reliability and durability against wind, snowfall, hail and other natural influences.
The possibility of arranging the attic.
Better hydro and thermal insulation.

The necessary theoretical minimum for the construction of the truss system

The pitched roof structure is made of metal or wooden beams. Metal is a more "problematic" material. It makes the entire roofing system heavier, cools down and heats up quickly, is more difficult to install and requires the use of professional welding equipment. Based on this, in the construction of private houses (especially with their own hands), wood is mainly used.

There are two main options for the implementation of the truss system for a gable roof - a hanging type device (each rafter leg has two points of support) and a layered method (the rafters are connected at the bottom by a puff, forming a triangular truss, a carrier beam is installed in the middle). A layered structure is necessary if between bearing walls there is a distance of more than 10 meters. Look at the image:

What does the system of truss elements consist of? Imagine a 3D projection. The skeleton of the roof consists of a mauerlat (rafter base), rafter legs, a ridge, racks, girders, lying, puffs, struts and battens. Mauerlat, lying and puffs are the lower parts of the system on which the entire future roof is being built. First, take a look at the illustration below, and then consider each element separately:

Mauerlat - the basis of all foundations

Mauerlat is a bar made of solid wood (mainly coniferous species) with a section of 10-15 cm. This optimal dimensions for the necessary strength and durability of the entire roof structure. The beam is laid on the load-bearing walls of the house to redistribute the spacer load on them.
There are two ways to install the bars of the truss base - with the transfer of load to the walls and without the transfer of gravity. The choice of mounting option for the Mauerlat should depend on the severity of the roofing system, the coating, the thickness of the load-bearing walls and the perimeter of the roof.

In the latter version, the Mauerlat is placed in a pocket, closer to the inner edge of the wall, and fastened to wooden corks with staples (each cork corresponds to the size of a brick and is part of the top row of brickwork).

The bars that take the load are mounted on the load-bearing walls from above with the help of anchors. Masters advise laying a rigid frame on a concrete base in the form of a belt in the wall. High-quality waterproofing is necessarily laid under the Mauerlat.

Details can be found in the video:

Lying - Basic Load Distributor

Lezhen performs functions similar to Mauerlat, and has the same dimensions. Beams are laid on internal load-bearing walls to evenly distribute loads from vertical struts and struts.

See the illustrations for the installation master class:

Rafter legs - ribs of the roofing skeleton

Rafters can be called the main component of the roof frame. This element cannot be left unused or replaced by another part. The legs of the rafters are wooden beams, the cross-sectional size of which can vary from 5 to 15 cm. The rafters rest on the Mauerlat and are interconnected by a ridge.

The installation process of the rafters can be seen in this video:

Skate - a small nuance with great meaning

The final element of the junction of two slopes is called the roof ridge. This is a rib located vertically at the highest point of the roof. A ridge run is mounted at the junction of the rafters. After that, the roof ridge is installed on it. This element fastens the rafters, performs a ventilation function and gives the roof aesthetics.

Racks - receivers of the main loads

Racks are powerful beams that take part of the load of the truss structure. They are installed vertically, usually in the center of the truss. If the project provides for an attic, then the racks are placed on both sides, closer to the roof slopes. When the attic is divided into two rooms, the racks are placed both in the center and on the sides.

Runs - rafter support

Ridge and side runs serve as a stiffener for roof trusses. The greater the load on the system (snowy winters, heavy roofing, large roof area, etc.), the more purlins should be installed on the roof slopes.

Tightening - truss element connector

This structural detail performs the function of fixing the rafters at the base. Thus, a rafter triangle is formed - a farm. Puffs may not be installed in layered systems.

Struts - the strength of the structure

The struts serve as a support for the uprights and strengthen all structural elements. Experts recommend installing struts at an angle of 450. This increases the strength of the system and protects it from deformation under the influence of snow masses and wind.

Lathing - the basis for a roofing cake

Lathing - horizontal wooden slats section 40-50 mm, located on the slopes perpendicular to the rafters. The main purpose of the crate is to fix the roofing material. The frequency and thickness of the battens depends on its type. In addition, the crate helps to move materials during the roofing and serves as an additional element of structural strength.

Overhang elements - final moments

The edge of a roofing system is called an overhang. This is a protrusion of the rafter system above the wall by about 40 cm. The overhang box consists of the following elements: filly (slats connecting with rafters), frontal and cornice boards. The purpose of the overhang is to protect the walls from getting wet during rains and melting snow.

A step-by-step guide to installing a gable roof truss system

To get started, we suggest that you familiarize yourself with the illustration that we have prepared for you:

And now consider the three main stages of the process of installing a simple gable roof truss system:

Stage 1: Calculations and drafting

Work should begin with the preparation of the roof project. It will contain all sizes, shapes and types of fasteners of structural elements. To create a quality project, you need to make the following calculations:

Calculation of constant and variable loads on the truss system. Constant loads include the weight of the roof and finishing materials (the attic is also taken into account additionally). Variable loads are the force of wind, rain, snow, etc. The maximum can be considered the main load of up to 50 kg per square meter roofs, and variable - up to 300 kg (taking into account possible snow blockages).
Accounting for seismic activity, storm winds and features of the location of the house. For example, if the house is surrounded by other buildings, then the load on the roof is significantly reduced.
The choice of the angle of inclination of the gable roof. When calculating the angle of inclination, the following factors are taken into account: the higher the angle, the more materials will go to the roof (and money, respectively); the slope depends on the roofing material - the softer the roof, the smaller the angle of inclination (for example, for soft tiles, an angle of 5-200 is selected, and if you use slate or ondulin, you must select a slope of 20-450).
Calculation of the pitch and length of the rafters. The step length between the trusses varies from 60 to 100 cm. The heavier the roofing, the more often the rafters need to be distributed. To calculate the length of the rafter, we use the Pythagorean theorem, taking rafter leg for the hypotenuse of the triangle. The first side will be considered half the width of the house, and the second - the selected roof height. Then we add another 60-70 cm of margin to the hypotenuse we found.

When all calculations are made, you need to make a drawing of parts, connections and the entire project as a whole.

Stage 2: Acquisition and preparation of the necessary materials and tools

For work, it is necessary to purchase lumber, according to calculations, bolts, corners, anchors and other connecting parts, and prepare the appropriate tools (drills, levels, meters, jigsaw, etc.). Wood for load-bearing beams and rafters must be solid and of high quality - knots and wormholes are unacceptable.

Antiseptic, anticorrosive and fire-prevention treatment of wood - obligatory moment at this stage. You can start working with the material one day after processing.

Stage 3: Installation of the roof truss structure

It is better to mount the roof frame in dry, not windy weather, so as not to encounter additional difficulties during operation. At this stage, we will dwell in more detail and consider step-by-step instructions for installing the truss system.

Installing the truss system: a step by step guide

Step 1. Laying the Mauerlat and the bed. There may not be a bed if there are no more load-bearing walls inside the house. Before laying the Mauerlat on the walls, it is necessary to lay a waterproofing material, for example, roofing material. We measure the tape of the desired width, cut it off and lay the waterproofing on the edge of the wall (where the frame will be installed).

We mark the beams of the desired section and length, trim and begin to form the base frame. Mauerlat should be located on the outer edge of the wall (if a hanging structure is planned) or in a special niche on the wall in front of the threshold (if the roof system is layered). The beds under the racks are laid on the internal load-bearing partitions. The Mauerlat is attached to the wall and wooden plugs with brackets, studs and anchors.

And we invite you to familiarize yourself with the illustration that we have prepared for you:

When laying the frame along the entire length of the wall, we may encounter the need to connect the base beam. They should be performed by cutting the bars at an angle of strictly 90 degrees. Fastening is carried out with high-quality bolts.

How not to damage bricks or blocks when lifting roof boards?

Choose the edge of the wall through which it is most convenient to feed the beams for the roof frame. This edge must be protected with a wooden square. Two trimmings of a rough board about a meter long will do, which need to be knocked together at a right angle. Put the square on the outer edge of the work wall. Now you can lift the boards without fear of damaging walls or window sills with them.

Step 2 Installation of rafters. The first step is to install the extreme rafters. In order for the rafters to be held evenly, we install the racks in the center. We attach the racks to the Mauerlat using iron corner and self-tapping screws. This temporary part is removed after the installation of all rafters. We fasten the extreme rafters with crossbars and install a ridge run. Mounting type - metal corner, self-tapping screws and studs.

The illustration shows the process of mounting the rafter legs and attaching the rafters to the run:

But how to attach the rafters to the Mauerlat:

Between the extreme farms, it is imperative to stretch the construction thread along which we will level all the slope rafters.

Now we mount all the truss elements according to a pre-marked scheme. We join the rafters over the ridge run.

For more information about the process of installing rafters, see this video:

A system of special racks will help strengthen the rafter legs. Attached to the Mauerlat wooden blocks from boards of the same thickness as the rafters. The bars must be fixed in increments equal to the selected distance between the rafter legs according to the markup. The length of each board is approximately 40 cm. These racks will transfer the load to the power plate and load-bearing floors. The bars must be fixed to the base with steel corners. Now the rafter legs need to be installed so that one side of each is adjacent to the rack. Then, on the other side of each rafter, we fasten the same rack and grab all three parts with 12 mm studs.

After mounting all the legs of the rack, they are cut flush with the bevel of the rafters from the side of the street. From the inside, an empty corner is formed between the racks, which must be closed with a wooden triangle (you can use trimmings from bevels).

All rafter legs should be additionally strengthened with crossbars, racks, struts and the joints should be reinforced with metal plates. The full process of strengthening the rafters can be viewed on the video:

Step 3. Waterproofing and crate. On the finished rafter ribs, you need to lay a high-quality waterproofing vapor-permeable material under the crate. The entry of the insulating sheet (sheet to sheet) is 15 cm. A counter crate of wooden slats is stuffed onto the waterproofing along the ribs of the rafters. From above, a crate of the same rails is installed perpendicular to the rafter legs.

When installing the frame, it is necessary to take into account the presence of a chimney and the obligatory ventilation of the ridge. The distance between the boards of the crate is on average 300 mm. This scheme is suitable for all types of solid roofs. When choosing a soft roofing material, the crate is made of solid sheets of moisture-resistant plywood.

The rafter system is ready. Now it's the turn of the installation of roofing material, internal insulation roof and attic arrangement (if provided by the project).

So, it's time to answer the main question of our topic: is it worth doing it all with your own hands? Do not believe anyone who tells you that it is easy and simple. But if you have golden hands and a great desire to make quality roof"for yourself", then go ahead! We wish you good luck!

The truss system of any object is equivalent to the value of the load-bearing structural elements of the house. The roof plays the role of a node under which the stiffening ribs of the building are assembled. Accordingly, when installing the roof with your own hands, it is required to give the maximum value to all structural units, even when using simple option- duplex.

Advantages of gable roofs

There are a lot of options for pitched truss systems. Among them, simple symmetrical is especially popular. Why? Here are her virtues:

On the basis of a gable roof, variations are created to reflect the special architecture of the building.
Simple calculations, easy to understand.
The one-piece design creates favorable conditions for the dryness of the internal space and the unhindered flow of water, snow and ice.
The maintainability, strength and durability of a gable roof are much higher than other options.

Depending on the size, homeowners always have the opportunity to equip roof space, make it a full-fledged floor or attic. In a word, a gable roof is the right and profitable solution for any object, whether it is a residential building, a summer house or a bathhouse.

Elements of the truss system

Depending on the type of roof structural elements differ. Without knowledge of the appointments of each, it is impossible to arrange a reliable coverage at home. Let's analyze in detail:

Mauerlat

The basis of the truss system. It is a beam with a section of at least 150 mm, or an I-beam channel, if the roof structure is metal. It is located on the bearing walls of the object. Its purpose is to distribute the load of the system evenly throughout the structure of the house.

Rafter leg

Structural basic unit of the system. Together with others, it forms a truss system - strengthening the strength of the entire roof. It is made of a wooden beam, which is not inferior in cross section to Mauerlat or profile pipes.

Rafter rack

Vertical bar or pipes. Depending on the variant of the gable roof, the pillars can be located in the center and / or on the sides. They take part of the weight of the entire truss system, which is why the cross section is 150 mm.

Rafter girders

Horizontal beams laid on racks and under the ridge to support the rafter legs. They provide structural rigidity and relieve stress on trusses.

Puffs and braces

Connecting beam for rafters. The action is similar - relieving the stress of a beam or metal and making the structure rigid.

lying down

Mounting support for racks and struts. To securely connect these two elements, you need a large cross-section beam - 150 mm or a thick-walled pipe of impressive diameter.

Lathing beam

Elements laid perpendicular to the rafters. Used to set the selected roofing and creating a multi-layer protective cake. The cross section is small - 40–50 mm.

If the intended roof structure is made of wooden beams, you should carefully consider the quality of wood upon purchase - the beam should not have interspersed knots, be made of soft woods.

Also, wood must have natural moisture, otherwise it will begin to dry right in the system structure, cracking, deforming the roof model, depriving it of reliability and safety.

Calculation of the truss system

Gable roof- complex design. The project takes into account many factors - natural nuances, wind, constant and variable loads. It is extremely difficult to make calculations on your own, without special knowledge about the climate of the area, the characteristics of the material for the manufacture of the system, and the nuances of pressure distribution.

Ideally, the calculations are at the mercy of professionals, you can independently choose only the material for coating - the following parameter depends on its type:

Tilt angle

The minimum angle of inclination of the roof relative to the parallel of the earth is 5 degrees. However, its dependence comes from the chosen roofing material. In this capacity, traditional slate, profiled sheet, flexible and metal tiles are used.

They are guided by the following rule: the steeper the slope, the more textured the roof can be.
From 5 degrees for laying rolled protective insulation of the roof. The number of layers matters - up to 15 degrees three-layer coatings, above - two- and single-layer coatings.

From 6 - ondulin.
From 11 - slate.
From 12 - corrugated board.
From 14 to 20 - metal tiles.
From 15 to 45 - soft roof.

Thus, the resulting precipitation - snow, water - will not linger on the surface, although complete cleaning requires one's own efforts or the involvement of specialists for the installation of the Anti-Ice system.

Determining the parameters of the rafters - step, length, section

The rarer the step, the more impressive the cross-section of the beam or the diameter of the pipes should be. As a rule, for load-bearing structures, this parameter is at least 150 mm, 100 mm for country houses and related construction - gazebos, baths, outbuildings.

Next, you need to set the number of rafters per slope: its length is divided by the installation step, which is from 60 to 100 cm + 1 extreme leg. Multiplying the result by 2 gives the total. Depending on the section of the beam, the amount of rafter legs and the installation step vary.

The length of the rafters is simply calculated if the school knowledge about the right triangle is left in the luggage. The rafter leg is equal to the hypotenuse of the resulting figure. The calculation is as follows: A² + B² = C², where - A is the height of the roof, B is half the length of the pediment, C is the length of the rafter leg. To the resulting value is always added from 30 to 70 cm for cornice overhangs.

Types of truss systems

Before getting down to work, it is important to choose a truss system option for a gable roof. There are few of them, each has its own advantages and disadvantages:

hanging

Suitable only for a standard roof width of 6 m, respectively, this is the length of the rafter leg. Fastening occurs by fixing the ends to the ridge run and the bearing wall. Be sure to install a puff that levels the stress and pressure of the structure.

In addition, they will play the role of load-bearing beams. Without them, the structure will disperse under weight. The advantages of the option are in the absolute dryness of the roof surface during the off-season, and in less deformation at the time of shrinkage.

Layered

The option is suitable for any roof width. Reliability and stability is ensured by fixing the bed to the Mauerlat. Thus, the pressure is leveled by the rack, which reduces the tension in the rafter legs. The advantage of the system is simplicity, but the design requires large investments - additional lumber is required to equip the beds.

hybrid

These systems are typical for multi-pitched roofs, where transitions are accompanied by numerous reinforcements, beams, posts, beds, slopes and other elements for the stability of the entire structure. The device is expensive and complicated, so only a professional should deal with the project and construction. At least curate it.

Do-it-yourself installation of a gable roof

So, when the option of the truss system is selected, lumber is purchased, a roof project is drawn up, you can get to work. You cannot deviate from the sequence of steps. This threatens to delay installation and loss of structural reliability.

Mauerlat mount

If the length of the beam for installing the Mauerlat is insufficient, an extension is made. Using the half-tree cutting method, the ends are connected. Additional fasteners are anchor bolts. Do not use self-tapping screws, dowels or nails - they are unreliable. Mounting to the wall is as follows:

There must be a margin of at least 5 cm from the edge.
Holes are drilled along the wall for inserting fasteners. Similar actions are carried out with a bar.
Mauerlat is attached to the edge with steel studs. The fastening step is more often 2 times than the distance between the rafter legs. Subsequently, before installing the main units, they are guided by metal marks.

Important - before laying the Mauerlat, the edge of the wall is protected with waterproofing. Spread one layer even if the house is made of wood.

Making and fixing rafters

Roof trusses are convenient in that they can be assembled on the ground in finished structure and move to the roof. This will reduce installation time, however, the model is heavy and lifting equipment will be required, which, of course, will increase the cost of the project.

For budget construction, another method is suitable:

At the bottom and top of the rafter legs, a gash is made to attach to the Mauerlat and the ridge run. This must be done separately with each unit, after lifting the wood up.
Places for fixing are marked on the Mauerlat and a ridge run is installed: racks are installed along the gables, on which a beam is placed. If the length is not enough, it is increased, but in a different way, unlike the Mauerlat - a board is screwed to the junction from both sides.
Depending on the chosen model of the truss system - layered, hanging - they make cuts in the ridge beam, Mauerlat or drill holes in them for fasteners.
Next, begin the installation of rafter legs from opposite ends of the roof, gradually moving towards the middle. Between the corners of the extreme trusses, it is not bad to stretch the cord to exactly match the entire horizontal part.
Between themselves, the rafter legs are connected by puffs and struts. Under the ridge part, at the angle formed by the rafters, wooden linings are stuffed, and the ends themselves are tightened with bolts.

More recently, professional builders have begun to use sliding fasteners for roof installation. Metal plates securely hold the bearing elements and at the same time move due to shrinkage. This cancels out its effects.

The work of fixing the rafters is hard and long. You should calculate the time in advance - you can not leave the roof unfinished during the rainy season, otherwise the rigidity of the structure will be lost in the future due to absorbed moisture.

Gables and framing

The side parts of the roof - gables, are made in the form of ready-made shields from boards and are completely installed at the top. Difficulties should not arise - it is only important to carefully file them at the required angle. It is necessary to fasten the crate only after the final appearance of the roofing is known. For instance:

Under the corrugated board, the step of the crate beam will be 440 mm.
The metal tile is fastened to the crate in increments of 350 mm.
A soft roof needs a solid plywood coating.

It is important to note the places for passage chimney- the crate should not come into contact with a brick or metal surface. The distance to the hot unit is at least 15 cm. Before installing the lathing, the finished roof is covered with waterproofing with allowances extending beyond the edges of the walls. Then the beam is mounted.

If it is decided to make a warming cake from above, then first the vapor barrier is strengthened from the inside, then the selected material is put into the boxes formed by the rafters. Next, waterproofing and wind protection.

Then it is required to re-mark the contours of the rafter legs with a beam 20 * 20 and then fill a new layer of the crate, along which the roofing material will be laid - the formation ventilation ducts. This method will save the capacity of the under-roof space if the owners are going to use it for a specific purpose.

Roofing material flooring

Regardless of the type of roofing raw material, installation starts from the edges of the roof and leads it up, laying one unit on top of the other. Thus, rain moisture will not get under the material.

The method of fastening depends on the type of material - soft tiles or tiles with a bitumen or polymer base are fused. Solid profiled sheets - ondulin, metal tiles - are fixed in pre-drilled holes to the crate, using rubber pads to seal and preserve the anti-corrosion layer.

As a result: the description of the installation of the truss system and the roof is easy only on the screen or paper. In reality, the process is complex and multifaceted. Therefore, if knowledge is not enough, it is better to invite professionals to work - their work is always guaranteed.

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 residential building small sizes- 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 square section 100x100 mm or 150x150 mm. Mauerlat takes on the load from the rafters and transfers it to the outer walls.

rafter legs- it long boards section 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 truss 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 for different levels, racks replace brick wall dividing the attic into two halves.

The installation process of the roof includes several stages: fastening the Mauerlat to the walls, assembling the truss trusses, installing the rafters on the floors, installing the ridge, fastening 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;
hammer;
nails and screws;
square and building level.

V 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.

V 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.

Third option: ceiling beams are released over the edge outer wall by 40-50 cm, and truss trusses are installed on 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 various materials from wood to siding.

Video - Do-it-yourself gable roof

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 paired rafter legs, connect all rafter pairs in order to impart overall rigidity to the entire roof structure. V various options roofs, 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 also be needed when purchasing. required material, and for the production themselves installation work. 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 circuit diagram gable roof devices 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 Mauerlat plane (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 - and elongation of the rafters 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 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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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 "at the forefront" becomes appearance buildings. 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 beneficial use 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.

21.02.2017 1 Comment

The truss system of a gable roof is a simple design that is available for a do-it-yourself device even for a novice developer. It is only necessary to make preliminary calculations, familiarize yourself with the details and stages of the construction of the roof, and calculate the materials needed for installation. When calculating, it should be taken into account that the bearing capacity of a gable roof depends on the influence of loads from wind, snow, and the weight of materials on it.

In order to make the process of building a gable roof truss system as easy as possible for you, below is a detailed step-by-step instruction for the installation of the truss system with their own hands.

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Requirements for building materials

For the device of the truss system the best option will use lumber from coniferous wood - pine, spruce or larch, I - III grade.

The material for the rafters is taken not lower than grade II, the mauerlat is made from boards or timber of grade II, for racks and girders material of grade II is taken, the crate is made of grade II-III lumber, it depends on the roof. Crossbars, puffs are made of Grade I material. On linings, linings, material of grade III can be used.

Note! Lumber must be dry with a moisture content of not more than 20%. Before installation, it should be treated with flame retardants and antiseptics against fungal diseases.

You need to store lumber under a canopy, providing protection from the sun and moisture. Level the storage area, shift the lumber with linings for ventilation.

For installation, fasteners are required: ties, plates, studs, bolts with washers and nuts, self-tapping screws with EPDM gaskets, 2.8 mm thick, mounting tape, galvanized brackets.

Brackets are used when fastening the Mauerlat, they are fastened with nails or self-tapping screws.

KR corners serve to attach the rafters to the Mauerlat, prevent the rafters from moving.

All fixing material must be made of high quality material and protected against corrosion.

Tools for the construction of the truss system

To install the gable roof truss system, you will need the following set of tools:

tape measure, different lengths 5, 10, 20 meters;
markers, pencils;
cord, for stretching;
hammers, different purposes, nail puller;
scissors, for cutting;
roofing knife;
putty knife;
Scotch;
hacksaws, electric saw, electric drill with various drills and nozzles;
screwdriver with nozzles;
markings, horizontal and vertical levels;
rails, rulers;
mounting foam;
safety belt and rope - for safe work.

Keep all roofing tools in a tool bag for safety.

Types of truss systems for a gable roof

sent rafters

Rely on Mauerlat and racks mounted on inner wall, with a step equal to the rafters. To give rigidity during spans of 6 m, struts are additionally placed.

The scheme of the rafters of a gable roof

hanging rafters

If the building is of small width, it is possible to arrange a truss system when the rafters rest on the mauerlat or walls, without intermediate supports. The maximum span is 9 meters. Such roofs can sometimes be arranged without a Mauerlat. The rafters are installed on the wall, using gaskets, on the rafters in this embodiment, a bending moment acts.

To unload, put wooden or metal lining. They securely reinforce the corner. For hanging rafters of a larger span, a headstock and struts are installed. For hanging systems, the rafters are arranged with a larger section, and the lumber is chosen not lower than grade I II.

Scheme of hanging rafters of a gable roof

Calculation of the truss system

It is possible to determine the cross-section of a gable roof beam required in the truss system by collecting all the loads acting on it: the weight of the coating, lathing, snow, wind pressure, precipitation.

Permanent loads can be determined by the weight of 1 m 2 of roofing, battens. It is important that the weight per 1 m 2 of the roof is in the range of 40-45 kg.

Variable loads from snow, wind are calculated according to the tabular values of SNiP normative documents, depending on the height of the building, temperature zone. The load from snow is equal to its weight multiplied by a coefficient depending on the slope of the slope. All these calculations are carried out during the project.

And if there is no project, and the roof is being erected on a small building? You need to look at the construction of a house in the neighborhood, which is carried out according to the project, the roof area is the same as your building. The gable roof truss system will serve as a model.

Rafter beam dimensions

At the top point, a ridge is laid that connects the rafters. The height of the ridge depends on the slope of the roof. The slope is influenced by the choice of coating material. The minimum dimensions are:

for tiled roofs, slate 22 gr.;
for metal tiles - 14 gr.;
ondulin - 6 gr.;
corrugated board - 12 gr.

The optimal angle is 35-45 gr. slope, provides a quick discharge of water and snow. In regions with strong winds, the roofs are made flat and then the angle of inclination is within 20-45 degrees.

You can determine the height by the formula: H \u003d 1 / 2 Lpr * tgA. Where A is the angle of inclination, L is the width of the building.

The task is simplified when using a ready-made table. The coefficient depends on the width of the building and the angle of inclination. Multiply the coefficient by 1⁄2 of the width of the building.

The rafters are made from pine or spruce bars, with a section of 50 × 100 mm, 50 * 150 mm.

The size of the rafters depends on the pitch. The pitch of the rafters is smaller, a larger number is installed, the cross section will decrease. The distance between the rafters at a gable roof is in the range from 600 mm to 1800 mm, it all depends on the design of the roof and the materials used for its construction.

Table of rafter sizes, depending on the step of their installation

Length rafters, mm	Distance between rafters, mm	Rafter beam section size, mm
up to 3000	1200	80×100
up to 3000	1800	90×100
up to 4000	1000	80×160
up to 4000	1400	80×180
up to 4000	1800	90×180
up to 6000	1000	80×200
up to 6000	1400	100×200

The roof does not end at the level of the walls, it is extended 500 mm outwards. The rafter leg can protrude, or a board or bar is built up. In this case, moisture does not fall on the wall, the foundation is not poured.

Step-by-step installation of the design of the gable roof truss system

The gable roof truss system consists of the following elements:

Mauerlat.
Lie down.
Racks.
Rafter.
Struts.
Puffs.
Crate.

Mauerlat installation

Mauerlat fasteners to a monolithic reinforced concrete belt

Mauerlat evenly distributes the load on the walls of the building, its installation can be done in several ways:

fasten to the wall through a reinforced concrete belt with studs;
studs are inserted into the masonry;
a simple and common way for simple roofs, fastening with wire rod.

For him, take a bar with a section of 100 × 100 mm, 150 × 150 mm or 200 × 200 mm. Which section to choose depends on the size of the roof and its coverage. The Mauerlat is joined along the length, for this, make a 100 mm cut, 500 mm long, fold the bars and fasten with studs.

In the corners, the Mauerlat is tied with cuts to the floor of the beam, fastened with brackets or bolts. For wooden buildings, Mauerlat is the last crown. On the brick walls, perform a monolithic reinforced reinforced concrete belt, with a section of 400 × 300 mm. Align the pins with a thread of 12 mm in diameter along the belt, through 120 mm, for fastening.

Drill holes in the Mauerlat with a diameter of 12 mm, lay them so that the pins go into the holes. Tighten with nuts from above. Previously, we lay two layers of roofing material or roofing felt under the bar. On the outside of the wall, lay the Mauerlat with bricks. Laying the Mauerlat on a horizontally and vertically even base. It is necessary to check the horizontal level of the surface. Check diagonals. Align with pads if necessary.

Installation instructions for beds, racks, rafters, struts and puffs

Do-it-yourself do-it-yourself installation of a gable roof truss system is carried out in the following order:

To carry out the installation of the bed, with the sent rafters.
Mark the installation step of the rafter legs.
Prepare according to the size of the rack.
Install them, if necessary, unfasten them with spacers.
Lay a run. Check geometry. Install fastener.
Try on the first rafter leg, mark the cutting points.
Mark the points and install the rafters at the beginning and end of the roof, pull a cord between them in order to align the rest of the elements with it.
Having installed the rafter leg, we attach it first to the Mauerlat, then to the ridge run, to each other.
Screw every second leg with wire to the Mauerlat.

The fastening of the rafters to the Mauerlat is done with the help of notches, thrust corners and a hemmed support bar. Reinforce with nails or staples.

Methods for attaching rafters to the Mauerlat

Install the support posts on the beds or linings and linings. A bed is a beam 50 × 100 mm or 50 × 150 mm, laid on the middle wall along a roofing felt lining. Place brick columns under the lining, 2 bricks high.

The rafter legs are connected to each other on the ridge. Consider the common connection nodes of the truss system:

They make cuts at one leg and washed down at the other. Insert one leg into the cut of the other and fasten with a bolt.
Install overlays, wooden or metal.
With the help of cuts in the run, they are fixed with nails or bolts.

Methods for connecting rafters on a ridge

For the stability of the roof to wind loads, puffs, struts and runs are installed. The tightening is a bar 100 × 150 mm, runs and struts are made from a bar 50 × 150 mm or 100 × 150 mm.

With the installation of contractions, the reliability of the rafter design increases. The sections of the beam are the same as the rafters. They are attached to the legs with bolts or nails. The bracing device adds rigidity to the structure. They are installed tightly, to the surface of the rafters.

Lumber has a standard length of 6 m. Rafters can be longer. Then you need to connect them. There are several connection methods:

Fasten by applying bars on both sides at the junction, connect them with nails in a checkerboard pattern.
Overlap, one part of the rafter to another, at a distance of 1 meter, fasten with nails in a variable order.
Run a cut obliquely, cut out part of the legs of the rafters, connect them, reinforcing them with bolts.

Lathing device

A crate is laid along the roof rafters. It serves to distribute the load from the roofing material, snow on the rafters. It plays the role of an air gap between the roof and the truss system.

The design of the crate depends on the accepted roofing material:

under soft tiles make the crate continuous, an anti-condensate film is laid on the rafters, pressed against the top with a counter rail, the crate is nailed onto it, then the OSB boards and the lining carpet, we lay the tiles on top.
under the roof of the corrugated board, the crate should be sparse. The step of the lathing depends on the brand of corrugated board, its thickness and the angle of the roof.
make a crate for standard slate in increments of 500 mm from a bar 75 × 75 mm or 50 × 50, as well as boards from 30 × 100 mm. It is necessary to take into account the design features of the roof, with the final choice of a suitable option.

The lumber from which the crate is made is pine of the first or second grade. It is advisable to take a width of no more than 14 cm. With a width of more, the boards can warp and damage the roofing. The length of the nails should be three times the thickness of the crate. Lay boards along the ridge. Set the first board of greater thickness to the height of the roofing.

To arrange a continuous crate along the slope of the roof.

With the first layer, lay a board along the ridge from it at a distance of 500-1000 mm next, and so on. With the second layer, lay the crate in the direction along the rafters. Arrange the joint between the boards only on the rafters in a run. The nail is sunk completely with the head into the pulp of the wood.

Cornice overhangs

Arranged to protect against precipitation, play an aesthetic role. Eaves overhangs suit tightly without gaps. The final stage in the construction of the roof.

Scheme of the device of the eaves overhang of a gable roof

Gable

The gable roof has two gables. They have the shape of a triangle, with the apex at the ridge and the sides coincide with the slopes of the roof. Gables support the rafters and enclose the attic space. Protect from wind and precipitation, give stability to the roof.

V wooden buildings the pediment is made frame. In brick buildings, frame or brick. Gables made of brick or gas block are erected before the roofing device. They require very precise execution.

Frame gables fit into the finished opening when the truss system is already assembled.

The frame is made of bars or boards. The frame elements are connected on spikes or to the floor of a tree, all fastened with nails. They are sheathed by nailing boards, lining or siding, maintaining the color in the decoration of the facade of the building. For the device of a window opening, an additional frame is made under it according to the size of the window. If the attic is insulated, then the pediment also needs to be insulated. Insulation is laid in the middle of the frame. A mineral wool insulation with reduced flammability is used. From the outside, the frame is upholstered with a hydro-windproof film or windproof membrane, from the inside under finishing material nail the vapor barrier film or vapor barrier membrane.

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