How to install a roof purlin. Assembly order of the truss system

The truss system is the basis of the roof, the reliability and strength of the roof, its ability to withstand precipitation and wind depends on it. The design of the truss system is determined by the shape of the roof and the features of the layout of the house, as well as the materials used. A do-it-yourself truss system is usually made of wood, but other materials, such as a metal profile, can also be used.

Types of rafters and their application

The choice of a truss system is a crucial step that requires knowledge of the design of each type of roof. Rafters can be:

1. Slanted rafters supported by ridge run and Mauerlat. They are used in the construction of a single-pitched, simple gable roof, and also as one of the elements of the hip and polyline mansard roof.
2. Sliding rafters - a type of layered rafters used for wooden buildings giving great shrinkage. Their difference is sliding mount rafters to the Mauerlat, which allows you to compensate for the shrinkage of the walls without deformation of the roof.
3. Hanging rafters - a system of rafters tied with crossbars or puffs, usually used in the construction of a simple gable roof, as well as the upper rafters of a mansard roof. In the hanging rafter system, there is no ridge run, and in the upper part the symmetrical rafter legs rest directly on each other.
4. Sloping rafters, otherwise called angular or diagonal. They are used to perform three-slope or hipped roof, as well as for roofs with complex geometry.

Elements of the truss system

Any rafters are designed to distribute and transfer the load of the roof to the walls of the house. The main elements on which the rafters rely are:

• Mauerlat - a beam fixed on the upper plane of the walls around the perimeter of the whole house;
• Beds - support bars laid on internal load-bearing partitions or columns;
• Beams of the ceiling of the upper floor;
• Racks and supports;
• Runs - horizontal support elements laid along the roof axis on racks.

The truss truss consists of the following elements:

• Rafter legs - boards or beams that form the contour of the roof and are laid with a certain step;
• Puffs or crossbars - horizontal elements that pull paired rafter legs together;
• Struts - supports set at an angle and supporting the rafter legs;
• Filly - boards fixed at the lower end of the rafters and forming roof overhangs;

Narozhniki - short rafters resting on diagonal rafters in a hip roof.

All these elements in private construction are usually made of wood - timber or boards. conifers dried naturally. The tree is impregnated with an antiseptic, which allows you to extend its service life. The thickness and section of the elements is determined by calculation.

Laminated rafter technology

1. Before construction begins, it is necessary to sketch the roof and calculate its dimensions. The cross section and pitch of the rafters, as well as the need to install additional supports and struts, are also determined by calculation.
2. Support elements are laid and exposed: mauerlat, beds and floor beams, racks, ridge and intermediate runs. These operations are described in detail in the articles on different types roofs:
3. Make a rafter template. To do this, take a board with a width corresponding to the estimated length of the rafters, with the same width, but with thinner- It is lighter and easier to precisely fit in place. The board is applied to the installation site of the extreme rafter with one end to the ridge run, the other to the Mauerlat.
4. At the top of the template mark the top gash. The shape of the cut should be such that the board lies on the ridge run and at the same time fits snugly against the opposite rafter. The depth of the cut should be no more than 1/3 of the width of the board.
5. After sawing out the upper cut, the template is once again applied in place and the lower cut is marked out - it should rest on the Mauerlat, without leaving large gaps. The end of the template is filed at an angle so that the cut is in a vertical plane.

   

6. The resulting template is applied at the installation site of all rafter legs, checking to see if a fit will be needed in place. If the template fits perfectly (which rarely happens), you can immediately make required amount rafter legs. If you need to adjust the bottom notch, then only the upper part of each rafter is cut out according to the templates, and the bottom notch is done in place each time.
7. The rafters are placed with established calculation step. Usually it is from 50 to 120 cm and depends on the type of roofing, namely on its severity, and on the expected snow load. The heaviest coatings are slate and ceramic tiles but they are now rarely used. More often, the choice is made in favor of more modern, light and reliable materials: metal tiles, ondulin, soft roof. For them, the pitch of the rafters can be chosen about 100 cm without performing complex calculations.
8. First, rafters are installed from the side of the gables. The rafter leg is supported on the ridge run and the Mauerlat and fixed on two nails 100-150 mm in each attachment point. Having installed the rafter pair, they additionally fasten it: in the upper part with the help of metal plates and self-tapping screws on one side and corners with a stiffener on the other, in the lower part - with brackets or also on the corners.

   

9. After installing the rafters from both gables of the roof, a twine is pulled between them and the rest of the rafters are aligned along it. Rafters are fastened in the same way.

   

10. Install struts, if required by the results of the calculation. The struts are made from the same material as the rafters. Apply a board of suitable length under right angle to the rafter and mark the bottom washed down. It is important to consider what the brace will rely on: on the floor beam or on the bed, the shape of the lower gash depends on this. After completing the lower cut, the brace is put in place and the cut line along the rafters is marked. The prepared brace is placed at a distance between the beams and rafters and secured with metal plates or corners.

Roof strut installation

Technology for the implementation of hip diagonal rafters

1. Since the rafters for hip roof installed diagonally. conventional ways their mounts don't fit. In addition, the load on diagonal rafters is much higher than on layered or hanging ones, so the material for their implementation must have a larger cross section. You can use a beam with a thickness of 100 mm or more, but practice shows that it is more convenient to make these rafters from two folded and fastened boards of standard thickness.
2. The diagonal rafters are supported by the upper end on the racks, the lower end - on the Mauerlat bars converging at right angles. They are marked in place, and their main feature is that the cuts are not made perpendicular to the plane of the board, but at an angle of 45 degrees. When making rafters from spliced ​​boards, first one side is performed with oblique cuts, then the second, in a mirror image.
3. Boards are pulled together by screws, nails or studs. Fasten hip rafters using pads and screws.

A video will help you better understand the basic techniques for building a truss system with your own hands.

When doing any rafter system with your own hands, it is important to carefully secure all knots and connections and remember that the roof is the main protection of your house from bad weather. Therefore, it is important not only to quality frame, but also choose the right one, for example, corrugated board, and lay it correctly.

During the construction of any building, the completion of the main work is the construction of such an element as the roof. Its importance is exceptional in general for the entire structure, because the basis is a special truss system. It is the rafters for the roof in the future that will have to withstand any load from external adverse factors.

In this article

Beginning of work

The construction of the roof of any building is carried out using wooden or metal rafters. It is a specially designed system of series-connected elements that provide bearing capacity the entire roof.

In preparation for the assembly of rafters for the roof, it is imperative to draw up a drawing indicating all dimensions. This will be needed when calculating the right amount building materials.

For wooden rafters it is worth using dried wood, which is not affected by fungus and rot. And also you can not use a tree in the presence of large cracks and splits on it.

Metal rafters for the roof should not have visible and hidden deformations. No areas of corrosion are allowed. And most importantly, in no case should roof rafters be installed without treatment with anti-corrosion compounds.

wooden rafters

Do-it-yourself wooden roof rafters do not present any particular problems even for people who do not have a special architectural education.

But we must remember that there are certain foundations from which you should not deviate. First of all - this existing species truss systems.

Dimensions of truss elements

For wooden rafters, the most common is the use of timber and boards.

For supporting elements, a beam section of 100 * 100 mm is taken. If a board is used, then the minimum is 100 * 50 mm. The size of the board is also allowed 200 * 50, but no more. If, in order to save Money it was decided to use logs, their minimum diameter should be from 100 mm. And at the same time they must be necessarily processed and cleaned.

Before putting the rafters on the roof, you can use a special Internet service for exact definition the required dimensions of all elements where you need to make the main parameters of the roof. Or you can make all the calculations manually, taking the data taking into account the snow and wind load in the required region of the country.

It must be remembered that minimum distance between the rafters should be from 60 to 100 cm. Otherwise, the roof may be unreliable and not withstand the subsequent operational load.

The sequence of installation of elements of a wooden truss system

To build a reliable roof with your own hands, you must follow a certain sequence of actions.

Fire-retardant composition increases the degree of fire resistance wooden materials in the event of a fire in an emergency.

Fastening truss elements

To fasten all elements of wooden rafters, self-tapping screws with a length of more than 70 mm should be used. They must be made of stainless steel or with anti-corrosion treatment. This helps to prevent the occurrence of spot rot, which can subsequently spread to all elements.

Special mounting plates, beam holders and beam connectors with mounting brackets must also be made of anti-corrosion materials.

To join each element, it is necessary to make geometric cuts. With their help, additional adhesion between structural elements will be provided.

to install metal rafters may require the use of a special welding equipment, since, in addition to the bolted nut connection, some elements require precisely welding together.

What is the result?

Following such simple rules and conditions, it will be possible to independently build truss system almost any complexity and required type, depending on the needs of the owner of the house.

It is worth remembering that in no case should you allow savings on the quality of building materials. And in case of doubts about the correctness of the actions performed and uncertainty about own forces You should definitely seek professional help.

It is better to entrust the installation of rafters to specialists, the roof is not the element of the building with which you can experiment. However, it is necessary to know the basics and features of how to put rafters on a house, if only in order to control the quality of work and be able to build a simple truss structure.

How to properly put the rafters on the house - let's deal with the terms!

If most people more or less imagine what a rafter is, then a problem may arise with the rest of the terms found in the case of a roofer. Mauerlat, crossbar, bed, stand, strut, run - it is unlikely to do without the help of specialized literature or an experienced builder! However, if you are reading this article, then you can do without them.

• Mauerlat is traditionally wooden beam with a section of 15 * 15 cm, which acts as an extreme lower support for the rafters, distributing the load from the joining points of the rafters to the entire upper wall area. AT recent times metal is often used instead of wood, for Mauerlats these are channels and I-beams. Mauerlat is installed with a slight indent from the outer edge of the wall and fixed. To prevent rotting and corrosion from below, the beams are insulated with roofing felt or other waterproof material. It is with this element that the installation of rafters often begins.
• Lezhen - additional beam to distribute the load from the rafters along the entire perimeter of the walls. They differ from Mauerlats in that the beds are installed inside complex truss structures, that is, they are not obligatory element roofs, but only as an addition in the right cases.
• Rack - vertical beam, which reinforces the truss structure from the inside. In turn, girders are installed on the racks, which are supported by struts - inclined beams that support horizontal elements and counteract compression or skew of the structure.
• Run - a horizontal beam that crosses the rafters perpendicularly along the entire length of the roof. Three types of purlins can be distinguished in the roof structure - ridge purlins (on which the rafters converge at the top of the roof), side purlins and Mauerlats, which are described above.
• Crossbar - a beam that is installed between the rafter legs, increasing the strength of the structure and its stability. Usually the cross section of the crossbars is 10 * 15 cm.
• Rafter legs or rafters - beams on which the roofing is directly installed. The rafter is also common name for all roof structure. For this element, a bar with a section of 10 * 15 cm is used. For the manufacture of a plank truss system, it is used pine board with a section of 50 * 150 mm or 60 * 200 mm.

Before installing the elements, it is necessary to accurately calculate their number, as well as take into account possible loads on the rafters: they can be one when installing slate, another for tiles and a third for.

For example, shed roof, built from a minimum number of elements, can easily withstand sheets of metal or slate, while under the tiles, over time, the rafters can deform, bend, which means that you will need to additionally strengthen the structure with racks or struts, and also use beams with a large section.

How to install the rafters - layered or hanging?

Rafter structures are divided into two groups - layered and hanging. Hanging rafters are usually built on the roofs of buildings without internal load-bearing walls. Hanging structure it rests on a ridge run and power plates, and at the bottom it is fastened with puffs, which prevent the rafters from moving apart under the influence of a load. It should be noted that on hanging rafters much more timber is taken away, since this ensures their stability. You can save wood on plank rafters, since log options take 15-20% more timber.

Sloped rafters are installed on those buildings that have load-bearing walls inside, since this type requires a minimum of three support points. Layered elements can block the span maximum length up to 6.5 meters. If there is a need to increase the width of the covered area, then this can be easily achieved by installing additional supports: with one additional riser, the width can be increased to 12 meters, and with two - up to 15!

Depending on the section of the beams that are used for the manufacture of rafter legs, the spacing of the rafters varies from 0.8 to 1.2 m. The construction of the rafter frame, including runs, racks and struts, provides special stability to the rafter legs. This type is most often used in private construction, since on the one hand it turns out strong and reliable roof, and on the other hand, layered rafters are very economical- wood on them, in comparison with hanging ones, is needed many times less. Quite often, a roof is constructed by combining both types.

How to put rafters on the roof - what for?

To begin with, guided by detailed instructions, as given in a separate article, calculate how much material you need. Before installing the elements of the truss structure, they must be treated with compounds against fungi, insects and flame retardants that prevent ignition. Having spent money on these compounds before putting the rafters on the roof, you will extend their service life by decades.

How to put rafters on the roof - step by step diagram

Step 1: Installing Mauerlats

The most important connection in the layered versions is the place where the rafter leg rests on the Mauerlat. It is with the fixing of the Mauerlat that the installation begins. To do this, metal pins are pre-concreted in the walls, which go deep into the walls by at least 40 cm. Wire twists with a diameter of at least 6 mm will also be suitable for the same purposes.

Step 2: Making the layout

Raise up two beams, which will be rafter legs. Cut notches on the left and right leg for emphasis on the Mauerlats, do not forget to mark for yourself which side of which beam belongs to. Install the bars, joining them at the top to make marks for the notches at the top. Notches are needed in order to make a connection with an emphasis, and not an overlap - this is considered extremely unreliable even with strong nailing.

Installation of rafters is one of the key stages in the construction of the roof. To prevent the rafter system from deforming and collapsing under high loads during operation, the rafters must be properly fixed.

Calculation of the pitch of the rafters

When designing a truss system, this issue is given Special attention. The strength characteristics depend on the section of the rafters and the step of their installation. roofing system.

The pitch of the rafters is the distance between adjacent rafters. The minimum pitch of the rafters is 60 cm, the maximum is more than 1 meter. A simplified version of the calculation of the pitch of the rafters involves the use of a table:

The length of the slope along the eaves must be divided by the rafter pitch selected in the table, then add one to the resulting value and round up to an integer. The resulting result indicates the required number of rafter legs per slope. Then the length of the slope along the cornice should be divided by the calculated number of rafter legs - the final number corresponds to the value of the center distance between the rafters.

This calculation method is general, it does not take into account the specifics roofing and the type of insulation used. If it is planned to lay a roll or slab heat insulator, it is recommended to adjust the pitch of the rafters to the size of the material. It should be noted that the width of the cotton insulation should be 1-1.5 cm more than the span between the rafter legs.

When determining how far to put the rafters, you should also pay attention to the recommendations for installing the selected roofing.

Material preparation

Do-it-yourself installation of rafters requires not only knowledge of the process technology, but also proper preparation wooden elements systems for installation. The rafters are made from edged board or timber, the section of lumber is selected at the design stage of the roof. The tree should not have cracks, wormholes or other damage.

Rafter legs should be made of well-dried softwood to prevent their deformation.

Wooden elements must be treated with fire retardant and bioprotective compounds. Before proceeding with the installation, it is necessary to decide on the method of attaching the rafters to the Mauerlat or beams, with the type of ridge connection. In accordance with the project, metal and wooden fasteners are selected, including:

• plates (made of metal or wood);
• bolts or studs with nuts and wide washers;
• nails, self-tapping screws, staples, etc.;
• wire rod.

Types of rafters and features of their installation

When erecting the roof of a house, hanging or layered rafters are used. In some cases, a combination of both may be used. Hanging ones rely only on the walls of the building, and layered ones require the installation of additional supporting structures, so this option is primarily used in the presence of an average bearing wall or support pillars inside the building box.

Sloped rafters bottom rest against the Mauerlat, respectively, the walls of the structure must have sufficient width for the installation of a special supporting structure made of timber with a section of 150 × 150 mm. Top part layered rafters rests on a ridge run. Thus, the installation requires the installation of a run, for which middle wall or poles should be mounted racks.

Hanging rafters rest only on the walls. This design can be mounted both on the Mauerlat and on thin walls without laying the Mauerlat. In this case, the floor beams protruding beyond the plane of the wall on both sides of the building serve as a support for the lower part of the legs. Hanging rafters are connected by a jumper (puff, crossbar) which relieves bursting forces. When covering large runs roof trusses intensify additional elements to enhance structural rigidity. When installing hanging rafters on a Mauerlat, a low puff can serve as a floor beam.

Before you put the rafters, you need to mount the scaffolding. This makes it possible to provide the necessary safety and convenience of work.

Installation of the upper ends of the rafters

When choosing how to install rafters, it is important to evaluate the complexity of the work and the weight of the truss structures. If the assembled farm has a relatively small weight, or it is possible to use lifting equipment, then the structures are easier to assemble on the ground, and then lift and mount on the roof. If the elements of the system are heavy and have to be lifted manually, then the trusses are assembled on the roof. The installation technology of roof trusses is described in the video instructions.

The connection of the upper ends of the rafters can be performed different ways. First of all, this is a butt mount. On the opposite rafter legs, cuts are made at the desired angle. Then the rafters are docked with the resulting ends and fastened to two nails. The connection is additionally reinforced with a wooden or metal lining.

The overlap of the rafter legs is carried out using bolts or studs with wide washers and nuts. In this case, the rafters are in contact with planes.

If the rafter system is mounted on wooden house with gables made of timber or logs, it is required to put the rafters on the walls using sliding fasteners in order to avoid deformation of the roof during shrinkage of the structure. Accordingly, in the ridge part, the rafters must be connected in a special way: the rafter legs must be located with a gap, and they are fastened with a special movable connecting element from metal.

In the presence of ridge beam installation of roof trusses on the ground is not required - the rafter legs are installed one at a time and attached to the ridge run.

The ridge run must be located strictly horizontally so that the rafter system evenly distributes the load experienced by the roof.

Methods for installing rafters on walls

The lower ends of the rafters are attached to beams or mauerlats. Hanging rafter trusses mounted according to the template rise to the roof. First of all, extreme farms are installed. In the tightening, two or three holes are required to attach the rafters to the beams laid on the upper crown of the log house.

If hanging rafters are mounted on stone building, it is required to use special fasteners - the so-called "ruff", made of durable steel. This fastener is driven into every fourth row brickwork. With the help of loops extending from the ruff, you can fix the beams. It is recommended to use a solid beam as a Mauerlat - in this case, the load will be evenly transferred to the walls.

On buildings made of brick or other material that is not prone to shrinkage, the rafters should be fixed rigidly. To do this, a cutout is made in the rafter leg, Bottom part which should lie firmly on the Mauerlat. The rafter is fixed with three nails (two are driven in on both sides at an angle, and the third is vertically on top) and tied with wire. A connection can also be used with the help of corners and a support bar that prevents the rafters from shifting.

Proper installation of rafters implies the implementation of a fire break in the place where the roof passes through chimney. If, during its arrangement, the installation of a special rafter system is provided, this should be taken into account when installing a shortened rafter leg (from the Mauerlat to the chimney structure). Between structural elements and pipe, the distance must be at least 130 mm.

Rafters serve as the basis of all roof structure, and their installation is one of the most important tasks in the construction of a house. The frame of the future roof can be made and installed independently, observing technological features roofs of different configurations. We will give the basic rules for the development, calculation and selection of the truss system, and also describe in stages the process of installing the "skeleton" of the roof.

Rafter system: rules for calculation and development

Rafter system - Basic structure, capable of resisting gusts of wind, taking on all external loads and evenly distributing them to the internal supports of the house.

When calculating the rafter structure, the following factors are taken into account:

1. Roof pitch:
   • 2.5-10% - flat roof;
   • more than 10% - pitched roof.
2. Roof loads:
   • constants - the total weight of all elements " roofing cake»;
   • temporary - wind pressure, snow weight, weight of people who carry out repair work on the roof;
   • force majeure, for example, seismic.

the value snow loads calculated based on the characteristics of the climate of the region according to the formula: S=Sg*m, where Sg- snow weight per 1 m2, m- calculation coefficient (depends on the slope of the roof). The determination of the wind load is based on the following indicators: type of terrain, wind load standards of the region, building height.

Coefficients, necessary standards and calculation formulas are contained in engineering and construction reference books

When developing a truss system, it is necessary to calculate the parameters of all components of the structure.

Roof structure elements

The truss system includes many components that perform a specific function:

Materials for the manufacture of rafters

Rafters are most often made from coniferous trees (spruce, larch or pine). For the arrangement of the roof, well-dried wood with a moisture level of up to 25% is used.

The wooden structure has one significant disadvantage- over time, the rafters can be deformed, so metal elements are added to the supporting system.

On the one hand, the metal adds rigidity to the truss structure, but on the other hand, it reduces the life of the wooden parts. On the metal platforms and supports, condensate settles, which leads to decay and damage to the wood.

Advice. When installing a truss system made of metal and wood, care must be taken that the materials do not come into contact with each other. You can use moisture barriers or apply film insulation

In industrial construction, metal rafters made of rolled steel (I-beam, brand, corners, channel, etc.) are used. This design is more compact than wood, but retains heat worse, and therefore requires additional thermal insulation.

The choice of truss system: hanging and hinged structures

There are two types of roof structures: hanging (spacer) and layered. The choice of system is determined by the type of roof, floor material and natural conditions region.

hanging rafters rely solely on the outer walls of the house, intermediate supports are not involved. Hanging type rafter legs perform work on compression and bending. The design creates a horizontal bursting force that is transmitted to the walls. With the help of wooden and metal puffs, this load can be reduced. Puffs are mounted at the base of the rafters.

A hanging truss system is often used to create an attic or in situations where roof spans are 8-12 m, and additional supports are not provided.

Rafters mounted in houses with an intermediate column support or additional bearing wall. The lower edges of the rafters are fixed on outer walls, and their middle parts - on the inner wall or bearing pillar.

Installation of a single roofing system over several spans should include expansion and layered roof trusses. In places with intermediate supports, layered rafters are mounted, and where they are not, hanging ones.

Features of the arrangement of rafters on different roofs

Gable roof

Gable roof according to building codes, has an angle of inclination up to 90°. The choice of slope is largely determined weather conditions terrain. In areas where heavy rainfall prevails, it is better to install steep slopes, and where strong winds- sloping roofs to minimize the pressure on the structure.

A common version of a gable roof is a design with an angle of inclination of 35-45 °. Experts call such parameters the "golden mean" of the consumption of building materials and the distribution of the load along the perimeter of the building. However, in such a case attic space it will be cold and it will not be possible to equip a living room here.

For a gable roof, a layered and hanging truss system is used.

hipped roof

All roof slopes have the same area and the same angle of inclination. There is no ridge run here, and the rafters are connected at one point, so the installation of such a structure is quite complicated.

It is advisable to install a hipped roof when two conditions are met:

• the base of the building is square;
• in the center of the structure there is a bearing support or wall, on which it will be possible to fix a rack that supports the junction of the rafter legs.

Create hipped roof it is possible without a rack, but at the same time, the design must be strengthened with additional modules - racks with puffs.

hip roof

Traditional design hip roof suggests the presence of rafters (diagonal), directed to the corners of the building. The angle of inclination of the slope of such a roof does not exceed 40 °. Diagonal runs are usually done with reinforcement, since they account for a significant part of the load. Such elements are made from a double board and a durable beam.

The joints of the elements are necessarily supported by a rack, which increases the reliability of the structure. The support is located at a distance of ¼ length large rafters from a skate. In place of the gable roof gables, shortened rafters are installed.

The truss structure of a hipped roof may include very long diagonal elements (more than 7 m). In this case, under the rafters it is necessary to mount vertical stand, which will rest on the floor beam. Sprengel can be used as a support - the beam is located in the corner of the roof and is fixed on adjacent walls. The sprengel farm is reinforced with struts.

broken roof

Sloping roofs are usually created to equip a larger attic. The installation of rafters with this version of the roof can be divided into three stages:

1. Installation of a U-shaped structure - supports for purlins that hold the rafter legs. The base of the structure is floor beams.
2. At least 3 runs are installed: two elements pass through the corners of the U-shaped frame, and one (ridge run) is mounted in the center of the attic floor.
3. Installation of rafter legs.

Gable roof: do-it-yourself installation of rafters

Calculation of the angle of inclination and loads

Calculation gable roof of course, you can do it yourself, but it’s still better to entrust it to professionals in order to eliminate errors and be sure of the reliability of the design.

When choosing the angle of inclination, it is necessary to take into account that:

• angle 5-15° is not suitable for everyone roofing materials, therefore, first choose the type of coverage, and then make the calculation of the truss system;
• at an angle of inclination over 45 ° - material costs for the purchase of the components of the "roofing pie" increase.

Snow load limits range from 80 to 320 kg/m2. Estimated coefficient for roofs with a slope less than 25° is 1, for a roof with a slope of 25° to 60° - 0.7. This means that if 140 kg of snow cover falls on 1 m2, then the load on the roof with a slope at an angle of 40 ° will be: 140 * 0.7 = 98 kg / m2.

To calculate the wind load, the coefficient of aerodynamic influence and wind pressure fluctuations are taken. The value of the constant load is determined by summing the weight of all components of the "roofing pie" per m2 (on average - 40-50 kg/m2).

Based on the results obtained, we find out the total load on the roof and determine the number of rafter legs, their size and cross section.

Installation of Mauerlat and rafters

Do-it-yourself installation of rafters begins with the installation of a Mauerlat, which is fixed with anchor bolts to the longitudinal walls.

Further construction of the structure is carried out in the following sequence:

Installation of rafters: video

Ways to connect the elements of the truss structure: video