Truss roof structure. Installing rafters of a gable roof with your own hands: a step-by-step process for installing rafters on a Mauerlat

The rafter system of a gable roof is designed for roofing in the form of two rectangles located at a certain angle to each other in the upper part of the structure. Such a design is quite often used in the construction of private low-rise houses, various buildings for domestic and economic purposes. In industrial and commercial enterprises, a gable roof is installed on buildings for various purposes, which have a significant length, exceeding the width by several times. The design contains two slopes of different lengths. On the front side, a short slope with a large angle of inclination is installed, on the back side - a long one with a smaller angle of inclination. This configuration allows the main part of atmospheric precipitation to be directed to the non-working zone of the enterprise territory.

Figure 1. Scheme of fillies.

The construction of a gable roof is one of the low-cost options that does not require significant physical effort.

It is relatively easy to perform with little experience with wood material.

Typical structural elements of the system, specific terms

Figure 2. Sheathing scheme.

In the manufacture of parts of the gable roof truss system, coniferous lumber is used. It is undesirable to use hardwood due to its high specific gravity. Most of the elements have specific names that are understood mainly by specialists:

Lezhen - timber with a section of 150x150 mm, 180x180 mm. Fits on the surface of the inner load-bearing wall. Designed to level the surface and distribute the loads from the racks.
A rafter leg, or rafter, is a piece of timber or thick boards. The main element of the triangular roof structure, bearing the main load from snow, rain, wind and other atmospheric phenomena. The distance between the rafter legs can be from 0.6 to 1.2 m. The step size mainly depends on the plumb line of the roofing material; in some cases, the peculiarities of the roofing material should be taken into account.
Mauerlat is a square beam with a side size of 150-180 cm. It is laid on the surface of external load-bearing walls. During installation, it must be secured with anchor bolts or other reliable means. Distributes the load from the rafter legs to the load-bearing walls.

All parts of the gable roof are connected to each other in a different way. Previously, structures were assembled mainly using staples, nails, threaded studs. Now manufacturers of building materials offer a wide range of different brackets for assembling roofs of any configuration. Fastening of most parts is carried out with self-tapping screws of the required diameter and length, reinforced with special spikes in the brackets.

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Additional elements of the rafter system

Figure 3. Schematic of an arch with three hinges.

In addition to supporting parts, additional reinforcing elements are used in structures:

Filly (fig. 1) - used to increase the length of the rafter legs. Installed at the bottom for eaves overhang. The thickness of the fillies is slightly less than the rafters.
Roof overhang, or cornice overhang, is a roof element protruding from the edge of the wall by about 40-50 cm. Designed to protect the walls from precipitation.
The ridge is an element that connects all the rafter legs of the system in the upper part. Installed horizontally.
Lathing (Fig. 2) - boards or bars installed for roof fastening. They are located perpendicular to the rafter legs, additionally performing the function of their fastening. They take the main effort from the roofing material, distribute it to the rafters. It is desirable to use edged lumber for the device. With limited funds, you can use unedged, cleaning it from the bark. If the roof is made of soft material, the lathing is made solid. This option can be made from boards or plywood treated with protective materials against high humidity. When corrugated board is used, the lathing is performed with a certain step, depending on the weight of the material and its design features.
Braces are elements made of timber or thick boards that reinforce the main structure. Distribute the force from the rafter legs to the supporting parts. The assembled structure of struts and puffs was called a farm - an enlarged part with the necessary safety margin.
Racks - made of rectangular or square sawn timber. Installed vertically under the slope. The load from the roof rafter gusset is distributed through the uprights to the internal load-bearing wall.
Tightening - a bar or board that secures the rafters in a hanging system. Creates a rigid triangle shape between the rafter legs, compensating for the spreading force.

For the manufacture of additional parts, you can use lumber with a cross section similar to the supporting parts. In order to save money, you can calculate and purchase products of a smaller section.

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Two typical ways of constructing truss systems

Figure 4. Connection diagram of the lower ends of the parts.

The gable roof rafter system can be arranged in two main ways:

hanging rafter system;
layered system.

The hanging system is used for buildings with a distance between external walls less than 10 m, without an internal load-bearing wall in the middle of the building. With a different building configuration, a layered rafter structure is used.

If the building has columns located along one of the central axes, it is possible to use the combined version. The rafter legs located above the columns are mounted with an emphasis on the surface of the columns, hanging rafters are installed between them.

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Hanging rafter system

In structures of this type, the installation of rafter beams is carried out on the surface of the outer walls. The disadvantage of this method is the emergence of an effort expanding the walls. To compensate for the load, the beams are tightened by tightening. The structure takes the form of a rigid triangle that retains its shape under the influence of loads. In some cases, floor beams can play the role of ties. This scheme is used when installing in the attic space of the attic.

Hanging rafters can be made in different ways:

A simple version of the arch with three hinges (Fig. 3) - the structure is a rigid triangle, the two sides of which are the rafter legs. The main load creates a bending force on the parts. The force on the third side is directed towards the tension of the structure, so a steel tie can be used instead of a wooden part. The connection of the lower ends of the parts can be assembled in various ways (Fig. 4), by inserting beams into a tie, using wooden elements or metal brackets.
Reinforced structure (Fig. 5) - a gable rafter system used to construct the roofs of large industrial buildings with a distance between the walls of more than 6 m. This system is not suitable for use in small residential buildings. The design feature is the distribution of the tightening weight per ridge. Since it is almost impossible to find solid lumber of the required length (6 m or more), the tightening is made from pieces. The connection of all elements is performed with a straight or oblique cut. The center piece is called the headstock. The connection of the headstock with a tightening is performed by a collet twist with the ability to adjust the tension.
An arch device with a tightening in the upper part of the rafter beams (Fig. 6) is used for equipment in the attic space of the attic. In this case, the tensile force in the rafter beams increases. The lower ends of the beams are attached to the Mauerlat beams. The fastening should limit the movement of the beams to the sides along the beam, but allow sliding across. This ensures an even load distribution and stability of the entire system. The roof beams should form an overhang.

Many variants have been developed for the arrangement of hanging systems. Most are used for relatively small structures without supporting structures inside buildings. For larger buildings, a layered rafter system must be used.

The gable roof has been popular for many years thanks to its simple, reliable and presentable design. Depending on the slope of the slopes, it is used in regions with different rainfall. The gable roof rafter system ensures natural precipitation.

Symmetrical - both slopes have the same length and are mounted at the same angle. Such a roof is an isosceles triangle with an obtuse or acute angle.
A sloping roof is created to accommodate an attic room, its rafter system implies a complex, two-level structure.
The different angles of the slopes are an original design that emphasizes the unusual architecture of the house.

Slope value

The angle of inclination is selected after analyzing several indicators: the type of roofing, the amount of precipitation, and the wind load. For regions with heavy rainfall, a small slope angle is recommended, but not less than 5 degrees. Snow masses do not linger on steep surfaces. Gentle roofs with obtuse slope angles are suitable for windy climates.

The gable roof rafter system must comply with accepted safety standards and be built in accordance with standards.

Rafter systems

The load-bearing elements and rafters take on the load from external forces and redistribute it to the walls of the building. The strength of the entire roof depends on their reliability. When constructing a structure, two rafter systems are used:

Hanging - rafter legs have two points of support on the walls of the building. They are subjected to compression and bending stress. With a span distance exceeding 8 meters, a headstock with struts must be installed. To reduce the impact of the rafters on the walls of the building, they are tightened together.
Inclined - these beams are supported on an internal wall or a special design.

If it is impossible to use one of the systems in its pure form, they resort to a hybrid design, which allows alternating hanging and layered rafters.

The device of the gable roof rafter system allows you to carry out calculations yourself, based on knowledge of geometry. To calculate the area of \u200b\u200bthe structure, you need to set the length of the ramp. The amount of material required depends on the angle of inclination. A sharp angle saves money, but at the same time minimizes attic space.

We calculate the ridge height, rafter length and roof area using geometric formulas. For clarity, fit schema at home. For example, let's take a slope angle of 45 degrees, the width of the house (the base of an isosceles triangle) - 6 m, length - 10 m.

First, divide the triangle in half with the height dropped from the top corner. It turns out two right-angled triangles, and one of the legs is the desired roof height. The height divides an isosceles triangle in half, which means that one leg is 3 m.The second is calculated by the formula:

3 × tg 45 0 \u003d 3 m.

Knowing the legs, according to the Pythagorean theorem, we calculate the hypotenuse, which is a rafter:

3 2 + 3 2 \u003d X 2.

The length of the rafter will be equal to the square root of 18, approximately 4, 25

The number of rafters is calculated by dividing the total length by a step (0.6 m):

10: 0.6 \u003d 16.6 - this value needs to be doubled.

We calculate the area by multiplying the length of the slope and the house and by multiplying the value by 2:

4.25 × 10 × 2 \u003d 85 m 2.

The supporting base for the roof is the Mauerlat - a durable timber with a section of 150 × 150 mm made of processed softwood. Its fastening is carried out on anchors embedded in the top row of the masonry. They should rise 2–3 cm above the timber to provide space for tightening the nut. A layer of roofing material is laid under the Mauerlat to protect it from moisture. A transverse beam is laid between the walls, fastening the Mauerlat and protecting it from longitudinal loads. To support the ridge, a special bar is laid along the slope - a bed, with a section equal to the Mauerlat. With a large building width, the installation of purlins is necessary.

The cross-section of the rafters is determined by the pitch and length of the rafter element, usually boards of 50 × 150 mm. Roof trusses are easier to assemble on the ground and ready to serve on the roof. For the template, two boards are taken, equal in length to the rafters, and connected with a nail. The free ends are laid on the supports, the resulting angle is fixed with a crossbar. The places and shape of the cuts are marked using a second template made of plywood. The bars are fastened at the desired angle with bolts, cuts are made on them, and after the truss they are raised up for installation.

The first to install the rafters on the gables. They are attached to the Mauerlat using corners or brackets. The first farms are set strictly according to the level. A cord is stretched between them, which is a reference point for installing the remaining elements.

To give sufficient rigidity to the entire structure, struts and crossbars are attached to the rafter leg. The ridge girder is bolted to each truss. This connecting element must be made of a sturdy bar.

With a significant width of the building, it is necessary to install purlins; this is a horizontal beam measuring 50 × 150 mm, supporting the rafters. For its installation, vertical racks are installed, resting on the bench. These elements will form the basis of the frame for the attic space.

To avoid water flowing onto the walls, it is necessary to provide an overhang; for this, the rafters are made hanging 30 cm or additional filly boards are attached.

A crate is stuffed onto the finished rafters, the required step is selected for each roofing material, and a continuous flooring is performed for bituminous tiles. Roof insulation is an important part of construction. It is possible to reduce heat loss to a minimum by correctly laying the insulation. For this, basalt wool is taken, the width of the material is equal to the step between the rafters, which allows you to quickly and reliably perform insulation. Laying waterproofing will help to ensure reliable protection of the roof from moisture.

The symmetrical gable roof model is the easiest to build and the most reliable option in operation. The load in the rafter system is evenly distributed, which allows you to extend the service life of the structure. Visual video lessons will help you master the subtleties of work.

Video

This video explains how to build a gable roof truss system:

In this video, you can see the rafter system using one gable roof as an example:

Properly designed and assembled according to technology, the roof serves as a barrier preventing cold air and moisture from entering the house. Outside, with the naked eye, we see only a small part of the structure - the roof covering. But the roof frame, which is the most important component, performs the main supporting functions and takes on the impact of wind and snow loads.

So that it does not deform as a result of operation, it is necessary to correctly calculate the size of the section of its elements and determine the distance between them, taking into account the weight of the roofing material, the slope and climatic conditions. In this article, we will tell you what the gable roof rafter system is, what it consists of, how it is designed and assembled with our own hands.

The rafter system for a gable roof of a house is a system of interconnected supporting elements, which together make up the frame of the structure.

It is made of wood or metal in accordance with the calculation of the loads that will act on them during operation. The roof truss frame performs the following functions:

Gives the required slope to the roof slopes... The traditional shape in the form of an equilateral rectangle of a gable roof is given by the rafter frame, which forms a slope between the base of the roof and its ridge. The angled surface allows snow and water to slide freely off the slope.
Distributes the load from the weight of the roofing cake... The weight of the roofing cake, taking into account the snow load, can reach up to 500 kg / m2, therefore the gable roof is subject to intense load, especially in winter. The rafters of the gable roof evenly distribute the weight that falls on them, and then transfer the load to the load-bearing walls and foundation of the house.
Serves as the basis for fastening thermal insulation and roofing material... The roof truss frame serves as a kind of skeleton of the structure around which its "body" is built. Thermal insulation should be installed between the rafter legs, and a roof covering is fixed to the crate, which protects against moisture penetration.

Please note that the structure of the gable roof truss system is quite difficult to design and assemble, especially if the master does not have enough experience. Indeed, in order for it to be able to withstand intense loads, it is necessary to correctly calculate the cross-section of the rafters and the pitch of the rafters, taking into account the slope and length of the slopes, the used roofing material, and also draw up a drawing according to which the assembly will be performed.

Types of truss systems

Rafter systems differ in many factors, their composition depends on the layout features of a wooden or brick house, the total weight of the roofing cake, the material from which the frame is made, as well as the type of roofing.

An important characteristic of a structure is their bearing capacity, which determines how much weight they can withstand without deformation. According to their characteristic features, the following types of rafter systems are distinguished:

Naslonnaya

A rafter frame of a layered type is called a frame, the rafters of which have 2 points of support. The upper end of the leg rests on a ridge girder mounted on vertical posts anchored to an internal wall. And with the lower end, it is installed on the Mauerlat.

The assembly of a rafter system of a layered type on a gable roof is possible only if at least 1 bearing partition or capital column is located inside the house. Such a structure is often called a non-thrust one, because the second point of support of the rafters compensates for the expanding load on the walls of the house, which is assumed by the hanging diagram of the frame installation.

The rafter legs of the layered type experience only a bend load, which can be eliminated by various struts. The rafter system allows you to overlap houses up to 14 meters wide.

Hanging

The hanging rafter system is distinguished by the fact that its rafters rest only with their lower end on a Mauerlat beam installed on the external load-bearing walls. The upper end of the rafter legs of this design does not rest on anything, but rather hangs in the air, which causes 2 types of load: bending and expansion.

The expanding load of such a layout of elements on the outer walls is so great that it has to be compensated for with the help of numerous crossbars and ties, due to which the rafter pairs are tied together.

The device of a gable roof with hanging rafters consists of triangular trusses, the rigid form of which is not subject to stress. It is believed that the complexity of the hanging circuit is much higher.

The rafter system of a gable roof with your own hands is easily mounted if you correctly calculate the pitch of the rafters, that is, the distance between the rafters and the size of their section.

Combined

Combining the best of both systems, it is recognized as the most reliable. It is used in cases when inside the building, not walls, but columns are used as a support inside the house. Then the hanging and layered rafters can be alternated in order to strengthen the structure with additional elements, without increasing the consumption of building materials.

Important! A sliding rafter roof is another type of frame, which differs in that the rafter legs are not installed on the Mauerlat using a rigid mount, but using a movable support. The sliding mount allows the roof to change its dimensions within the power reserve during the shrinkage of the wooden house.

Design

The device of the rafter system of a gable roof of any of the listed types is a combination of auxiliary and supporting elements. They evenly distribute the weight of the roofing cake, and also compensate for the expanding and bending loads that arise between them.

The cross section, length and pitch of the rafters are determined using an engineering calculation that takes into account the weight of the roofing cake, climatic conditions in the construction region, and the slope of the structure. The structure of the rafter frame of a gable roof usually includes the following elements:

Mauerlat... Install the Mauerlat beam on the outer walls of the house, on which the roof slopes rest. It serves to soften the pressure on the supports and evenly distribute the load from the weight of the roofing cake. It is made of a durable bar with a section of 150x150 mm or 200x200 mm and is attached to the upper chord of the walls using anchor bolts or long metal studs.
Sill... This is an analogue of a Mauerlat, only it is installed on internal load-bearing walls, and it is necessary to expose vertical resistant ones for mounting a ridge run on it.
Rafter legs... This term designates frame elements that are made of boards with a section of 150-40 mm and are installed at an angle to the base of the roof, forming the slope angle. What is the distance between the rafters, their length and thickness are determined by calculation, taking into account the total loads to which they are subjected during operation.
Tightening... Tightening is called beams that are placed horizontally and connect the legs of one rafter pair together in order to reduce the bursting load on the outer walls of the structure. The crossbar is a tightening installed under the very ridge of the structure.
Racks... A rack is a vertical bar that is placed on a bed to support the ridge run. Determining what distance should be between the posts is easy, because it repeats the step of the rafters.
Braces... Diagonally located supports that support the rafter legs in the middle or at the bottom, preventing them from bending, are called struts.

Please note that only the calculation of temporary and permanent loads to which they will be subjected during operation can determine how to correctly position the elements of the rafter system. Calculating the total weight of the roofing cake helps to determine the correct distance between the rafters, calculate their length and the required thickness.

The calculation of the rafter system of a gable roof is based on the fact that in the frontal size it has the shape of an equilateral triangle, the sides of which can be easily calculated using simple trigonometric formulas.

These simple calculations help determine the optimal distance between rafters, their thickness and length. The design calculation is performed in the following sequence:

Determine the structure and slope of the roof... There are various ways to choose the type and slope of the roof structure. This parameter depends on the climatic conditions and the performance characteristics of the selected roofing material.
Determine the total load on the structure... To do this, add up constant loads (the weight of the roof covering, its own weight of the frame, thermal insulation and floors) with temporary loads (snow load, wind load), multiply by a correction factor that takes into account the slope of the slopes, and then add 10-15% to this figure so that the frame had a certain margin of safety.
Calculate the length of the rafter legs... For this, they use the Pythagorean theorem, because the truss truss is an equilateral triangle. It turns out that the square of the length of the rafter leg is equal to the sum of the squares of the height of the blood and half the length of the inception. Knowing how to calculate the length of the rafters, you can calculate the height of the ridge.
Determine the section of the elements... The optimal section of the elements is chosen according to the tables in accordance with the length of the rafter legs and the distance between them. The more these indicators are, the thicker the rafter should be.

Remember that before you calculate the rafters for the roof, you need to decide on the basic design parameters. In particular, it is necessary to know exactly the height of the ridge and the slope of the roof, as well as the dimensions of the room to be covered. The result of the calculation of the roof elements should be a detailed diagram of the rafter system, reflecting their dimensions and the angles between them.

We calculate the angle of inclination

The angle of inclination of the slopes is selected not depending on aesthetic preferences, but based on weather conditions, taking into account the roofing material. Steeper ramps of 40-45 degrees are constructed in areas with a large amount of snow cover, and more gentle 10-20 degrees in places with strong gusty winds.

Keep in mind that the steeper the slope, the higher the consumption of materials, the higher the total cost of the roof. Be sure to take into account the requirements of the material:

Tiles, slate require a slope of at least 22 degrees, otherwise, sediments seep through the joints between the elements.
The metal tile is laid at an angle of at least 14 degrees, since it suffers greatly from gusts of wind, it can deform or even fly off.
The soft roof allows an angle of inclination of up to 5-10 degrees, making it possible to cover slopes of any geometry with it.
Ondulin is considered one of the most reliable materials and can even be used for roofs with a slope of less than 6 degrees.
Profiled sheets should not be laid at an angle of less than 15 degrees, however, even slopes with an acceptable slope should be treated with a sealant for better waterproofing.

Assembly technology

Before installing the roof frame, it is necessary to perform the calculation of the parameters of its elements, based on the calculation of the total load on the structure, and also create a detailed drawing reflecting its results.

Having a frame diagram in front of you, it is much easier to qualitatively carry out the installation of a gable roof rafter system. The assembly technology of the structure implies the following sequence:

First, a Mauerlat is laid on the upper belt of the outer walls, on which the slopes will rest, and a bed is mounted on the inner partitions, if the system is layered. These elements must be firmly fixed with anchor bolts or studs.
Then the rafters are fastened. They are fixed with nails to the Mauerlat, and also connected to each other using a metal plate. It is worth recalling that drunk is made in the rafters under the Mauerlat beam, and not vice versa. First, the rafters are installed, located on the edge, in order to set the level along them, along which the remaining pairs will be aligned.
After installing the rafters, auxiliary supporting elements should be installed that will support them - struts, tightening, contractions. To fix the crossbar more reliably, its end is made with a ledge in half the thickness of the bar and it is cut to the rafter, fixing it with nails in several places.
A crate is nailed on top of the rafter legs, onto which the roofing material is fixed. The material and pitch of the battens are selected in accordance with the characteristics of the roofing material and the slope of the roof.

Remember that a well-designed and well-assembled rafter system is the key to the strength, reliability and durability of a gable roof. Therefore, do not neglect the help of professional roofers and designers when creating a roofing project for your home.

Video instruction

21.02.2017 1 Comment

The rafter system of a gable roof is a simple design, available for a do-it-yourself device even for a novice developer. You just need to make preliminary calculations, get acquainted with the details and stages of roofing, 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 effect of loads on it from wind, snow, and the weight of materials.

In order for the process of building a gable roof rafter system to be given to you as easily as possible, below are detailed step-by-step instructions for installing the rafter system with your own hands.

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Requirements for building materials

For the device of the truss system, the best option would be to use sawn timber from coniferous wood - pine, spruce or larch, I - III grade.

The material for the rafters is taken at least grade II, the Mauerlat is made of boards or timber of the II grade, for the racks and girders, the material is taken for the II grade, the lathing is made of lumber of the II-III grade, it depends on the roof. Crossbars, tightenings are made of Grade I material. Grade III material can be used for linings, linings.

Note! The lumber must be dry with a moisture content of no more than 20%. Before installation, it should be treated with fire 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 spacers for ventilation.

For installation, you will need fasteners: ties, plates, pins, bolts with washers and nuts, screws with EPDM gaskets, 2.8 mm thick, mounting tape, galvanized brackets.

Brackets are used when attaching the Mauerlat, fasten them with nails or self-tapping screws.

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

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

Tools for the construction of the rafter system

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

tape measures of 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 attachments;
screwdriver with nozzles;
markings, horizontal and vertical levels;
slats, rulers;
mounting foam;
safety strap and rope - for safe work.

All tools on the roof should be kept in a tool bag for safety reasons.

Types of rafter systems for a gable roof

Sent rafters

They are supported by a Mauerlat and racks installed on the inner wall, with an equal pitch to the rafters. To give rigidity with spans of 6 m, braces are additionally installed.

Diagram of layered rafters of a gable roof

Hanging rafters

If the building is small in width, you can arrange a rafter system when the rafters rest on the Mauerlat or walls, without intermediate supports. The maximum span is 9 meters. Sometimes such roofs can be arranged without a Mauerlat. The rafters are installed on the wall, using spacers, on the rafters in this version, a bending moment acts.

To unload, wooden or metal plates are placed. They securely reinforce the corner. For hanging rafters of a larger span, a headstock and struts are installed. For hanging systems, the rafter is arranged with a larger section, and the lumber is chosen at least I II grade.

Diagram of hanging rafters of a gable roof

Calculation of the rafter system

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

Constant loads can be determined by the weight of 1 m 2 of roofing, lathing. 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 \u200b\u200bof the SNiP normative documents, depending on the height of the building, the temperature zone. The load from the snow is equal to its weight multiplied by a coefficient depending on the slope of the slope. All these calculations are carried out in 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 a project, the roof area is the same as your building. The gable roof rafter system will serve as a model.

Dimensions of timber for rafters

At the top point, a ridge is laid, which 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 tile roofs, slate 22 gr .;
for metal tiles - 14 g.;
ondulin - 6 gr.;
corrugated board - 12 gr.

The optimal angle is 35-45 degrees. slope, provides 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 / 2Lpr * tgA. Where A is the angle of inclination, L is the width of the building.

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

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

The size of the rafters depends on the pitch. The step of the rafters is smaller, a larger number is installed, the 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 structure of the roof and the materials used for its construction.

Rafters size table, depending on the step of their installation

Length rafters, mm	Distance between rafters, mm	The size of the cross-section of the rafter beam, 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 outward by 500 mm. The rafter leg can protrude, or a board or block is built up. In this case, moisture does not fall on the wall, the foundation is not poured.

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

The rafter system of a gable roof consists of the following elements:

Mauerlat.
Beds.
Racks.
Rafters.
Braces.
Puffs.
Lathing.

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:

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

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 in length, for this, make a wash down of 100 mm, 500 mm long, fold the bars and fasten with pins.

In the corners, the Mauerlat is tied with cuts into the floor of the timber, fastened with staples or bolts. At wooden buildings, this is the Mauerlat, the last crown. On brick walls, make a monolithic reinforced reinforced concrete belt with a section of 400 × 300 mm. Along the waist, place pins with a thread of 12 mm in diameter, every 120 mm, for fastening.

Drill holes with a diameter of 12 mm in the Mauerlat, lay them so that the pins go into the holes. Tighten with nuts from above. First, we put two layers of roofing material or roofing felt under the bar. On the outside of the wall, lay the Mauerlat with a brick. Lay the Mauerlat on a horizontal and vertical base. It is necessary to check the level of the horizontal surface. Check the diagonals. Align with shims if necessary.

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

The device of the rafter system of a gable roof with your own hands is performed in the following order:

Install the bed with the rafters sent.
Mark the step of installing the rafter legs.
Prepare to fit the rack.
Install them, if necessary, unfasten with spacers.
Lay the purlin. Check geometry. Install the hardware.
Try on the first rafter leg, mark the trim points.
Make a marking of the points and install the rafters at the beginning and end of the roof, pull a cord between them in order to align the other elements along it.
Having installed the rafter leg, we first attach it to the Mauerlat, then to the ridge run, to each other.
Wire every other leg to the Mauerlat.

The fastening of the rafters to the Mauerlat is done using cuttings, persistent corners and a hemming support bar. Reinforce with nails or staples.

Methods for attaching rafters to Mauerlat

Place the support legs on the beds or pads and strips. Lezhen is a beam of 50 × 100 mm or 50 × 150 mm, laid on the middle wall along the roofing felt. Lay brick columns under the lining, 2 bricks high.

The rafter legs are connected to each other on a skate. Consider the common joints of the rafter system:

They make cuts at one leg and washed down at the other. Insert one leg into the cut with the other and fasten it with a bolt.
Install lining, wood or metal.
With the help of cuttings in the girder, 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 girders are installed. Tightening is a bar of 100 × 150 mm, purlins and struts are made of a bar of 50 × 150 mm or 100 × 150 mm.

With the installation of contractions, the reliability of the rafter structure increases. The cross-sections of the timber are the same with the rafters. Attached to the legs with bolts or nails. The device of struts adds rigidity to the structure. They are installed tightly, to the surface of the rafter

The lumber has a standard length of 6 m. The rafters can be longer. Then you need to dock them. There are several ways to connect:

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

Sheathing device

A crate is arranged along the roof rafters. It serves to distribute the load from the roofing material, snow onto the rafters. Plays the role of an air gap between the roof and the rafter system.

The design of the battens depends on the adopted roofing material:

under the soft tiles, the sheathing should be made continuous, an anti-condensation film is laid on the rafters, the counter rail is pressed on top, the batten is nailed onto it, then OSB boards and underlay carpet, we put the tiles on the 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 inclination of the roof.
lathing for standard slate should be made with a step of 500 mm from a bar of 75 × 75 mm or 50 × 50, as well as boards from 30 × 100 mm. Consideration should be given to the design features of the roof, when making 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 the width no more than 14 cm. If the width is more, the boards can warp and damage the roofing. The length of the nails should be three times the thickness of the sheathing. Lay the boards along the ridge. Install the first board with a greater thickness to the height of the roof covering.

Arrange a continuous crate along the roof slope.

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

Eaves overhangs

Settled up to protect from atmospheric precipitation, play an aesthetic role. Eaves overhangs fit tightly without cracks. The final stage of roofing.

Diagram 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 an apex at the ridge and the sides coincide with the roof slopes. The gables support the rafters and enclose the attic space. Protect from wind and precipitation, give roof stability.

In wooden buildings, the pediment is made frame. In brick buildings, frame or brick. The gables are made of brick or aerated concrete, erected before the roofing device. They require very precise execution.

The frame gables are inserted into the finished opening when the rafter system is already assembled.

The frame is made from bars or boards. The elements of the frame are connected on thorns or in the floor of a tree, all are fastened with nails. Sheathed by nailing boards, lining or siding, maintaining the color scheme in the decoration of the facade of the building. For the device of a window opening, an additional frame is made for 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 a low flammability is used. From the outside, the frame is upholstered with a hydro-windproof film or a windproof membrane, from the inside, a vapor-proof film or a vapor-proof membrane is nailed under the finishing material.

In contact with

Perhaps the main decoration of any house is the roof, without which it is difficult to imagine any structure. The roof gives a private home a holistic appearance and defines its style. However, first of all, it acts as an engineering structure designed to protect people from the destructive effects of the external environment.

Today, the use in the construction of houses of various elements of architecture, undeservedly forgotten earlier, is returning to fashion. For example, mezzanines, bay windows, attics are increasingly common, giving the building a stylish and interesting exterior. At the same time, you can achieve a noticeable increase in internal space at a relatively low cost of money.

The roof rafter system is considered the most strong, durable structure... It is distinguished by its ease of installation, ease of fit and the ability to withstand heavy loads, while being relatively light in weight. The rafter system is a special design with a triangle lying at the base. Its rigidity is achieved by attaching the rafters and the roof frame to each other. The most common options are made of wooden logs or beams, however, there are also systems made of galvanized steel.

Types of truss systems

Experts distinguish between several types of rafter systems. They are accepted classified by shape and type of roof:

hipped;
tricycle;
gable;
hip;
half-hip;
broken lines.

Gable rafter system the roof is the cheapest and easiest option. The main advantages of this design include simplicity, reliability and the ability to withstand significant loads. However, it is worth describing some of the disadvantages. Namely, the impossibility of implementing any special design solutions due to the simplicity of the shape of such a roof. However, this disadvantage can be easily compensated for by decorating the house with various decorative elements. The second drawback can be called more significant - the internal space is small, significantly different from the parameters of the sloping roof.

The most common and recognized among fans of interesting architectural solutions is sloped roof rafter system... In this case, there is an opportunity for the manifestation of imagination, of course, subject to the established building standards and strength characteristics. This design can be of the correct or asymmetrical shape and is determined based on the structure of the house itself, as well as the design and layout of the interior of the room.

Sometimes you can get an extremely interesting room under the roof by correctly installing the rafter system and organically using a second light or mezzanine. In order to maximize the usable area of \u200b\u200bthe house and make it cozy at relatively low financial costs, it is very important to be able to effectively and fully use the available space.

Features and requirements for the rafter system

The size of the rafters, which are elements that determine the strength and slope of the roof, it is necessary to calculate individually for each private house, taking into account the total area and geometric shape of the roof, as well as the distance between the walls. Depending on the results obtained, it will be possible to determine the appropriate cross-section of the beams. Typically, this figure is about 1 meter.

In practice, they use two types of rafters:

An inclined structure that rests on the walls of the house along the entire perimeter, and in the center it is supported by an additional or intermediate support. It is advisable to use if the distance between several supports is not more than 6.5 m.
Hanging rafters, fixed at the top of the ridge and abutting against each other. This system is distinguished by a particularly reliable connection of the walls to each other.

In general, the device of the rafter system directly depends on the type of material from which the house is made. For example, for a building built of brick, a rafter system is recommended, which rests on a separately constructed support from beams of a small section or a Mauerlat. As a support for the rafters of a wooden structure, the upper crown of a log house is best suited, and for frame-type houses, an upper strapping is used.

The main parts of the roof truss system

The base of the roof on which installation of roofing cake and the inner lining of the room is precisely the rafter system. Often it is also used as a basis for communications and engineering systems. The combination of various nodes and elements that make up the structure of the roof truss system performs the function of transferring power loads directly from the roof to the load-bearing walls of the structure. The main parts include:

Hanging and inclined rafters.
Mauerlat.
Ridge and side runs.
All kinds of connecting elements such as struts, diagonal ties, spacers.

As a rule, the load on the roof truss structure is very high. It is determined individually, taking into account the design features of the roof and the local wind and snow loads. The installed rafters must be able to withstand such loads, and also have the necessary margin of safety to withstand possible gusts of wind or snow.

In order to determine the basic parameters of the nodes of the roof truss system, it is necessary perform special calculations... They will help you to accurately determine the profile, length and section of each of the structural elements, as well as the features of the interaction of parts with each other. The strength of the entire structure largely depends on how tightly the nodes of the roof truss system are connected. Recommended to apply the following types of connections:

Which type of connection is suitable for a particular system can be determined based on the design load, design features and materials used.

Installation principles

Installation work carried out in three main stages... In particular, the markings, taking into account the location of window openings, hoods, chimneys, mounting the Mauerlat and its reliable fastening to the bearing support. Next, the roof trusses are erected and, finally, the ridge is installed.

Installation should begin with laying the Mauerlat on top of the walls and attaching the rafters directly to it. They must be installed in the desired position and secured from one end to the support, and from the other to the ridge bar. For reliability, the connections can be fixed to each other with additional studs with a diameter of 8 -12 mm.

When constructing a truss structure, the most common wrong calculation is a mistake the size of the rafters, which can lead to sagging of the roof.

It is necessary to foresee each element and unit, to deal with the technology at the preliminary stage. In this case, it is also recommended to plan the eaves overhang with a length of 60 cm, which will reduce the effect of weather on the walls of the house.

For wooden structures that can dry out over time, the most correct mounting option would be bolted connections, capable of adding rigidity to the entire structure.

Subject to all the basic rules, the installation of the roof truss system can be done relatively easily. However, it is important to adhere to the chosen technology precisely to avoid the risk of various problems.