Installation of a rafter system under a metal tile for a gable roof and calculation of the pitch of the rafters. The distance between the rafters: learning to choose the right rafter step

It is pointless to argue about the importance of the roof for any building. It is not for nothing that over a dozen different types of roofs have been invented in the history of mankind, from simple to quite complex in design and construction. An important element in planning the construction of a roof is the step between the rafters - strong bars that are the basis of the structure. This will be discussed in this article.

The distance between the base of the roof slopes is not a constant value and depends on the following components:

type of roof;
slope angle;
the type of roofing material to be installed;
rafter section dimensions.

Before proceeding with the process of erecting the upper structure of the house, a calculation should be performed by determining the optimal distance between the rafters.

Gable roof rafter pitch

The most widespread in our country are gable roofs. They are a structure that has two parallel planes, with an angle of inclination relative to the horizon from 20 to 50 degrees.

Insufficient roof pitch gable roof in snowy areas there is a danger of accumulation of large snow masses, which can lead to the destruction of the structure. An increase in the slope angle in regions with a predominance of strong winds is also fraught with a high load and the risk of breaking not only the roof, but the entire structure as a whole.

Mansard roof truss system

Most private houses have an exploited under-roof space called an attic. This design is characterized by an increased height of the slope, which is caused by the need to create a living space of a comfortable height. Typically, stingrays mansard roof broken lines with a varying angle of inclination. For their installation, a double truss system is used.

The steepness of the lower slopes of the mansard roof significantly exceeds the slope of their upper extensions. The plane load perceived by them is not great. Thanks to this, the rafters in the lower part can be installed with a maximum pitch. The upper ridge slopes are recommended to be mounted with a reduced gap from each other.

Rafters in a shed roof

For outbuildings and some private houses, roofs with one slope are used. Due to the limited angle of inclination, high pressure is exerted on them. Experts recommend for rafters shed roof use lumber of increased cross-section, with a minimum step setting from each other.

When calculating the distances at which roof beams are installed, special attention should be paid to the amount of snow load in a particular area. With a small slope, this characteristic is of great importance. Roofing material for such roofs is best chosen with a minimum dead weight, which will reduce the bending load.

Hip roof truss system

The hip roof truss system is considered the most difficult in construction. This type is called four-pitched, since the roof is formed not only by side, but also by additional end slopes, where the installation of rafters is carried out not on the ridge, but on the corner bowstrings. This places special demands on the organization of the roof frame.

Under the hip roof, the attic is not often arranged. This is due to the small angle of inclination of the rafters and the roof as a whole. In the case of an increase in the angle of the slopes to the horizon, the distance between the rafters is increased, with a decrease, vice versa. An additional aspect of the calculation is the used roofing material.

The dependence of the pitch of the rafters on the roofing material

In addition to variable snow and wind loads, a constant (static) one also acts on the roof, the force of which depends on the roofing material used. It's no secret that different kinds roofs have their own weight, which can differ by 10 or more times.

The right choice of material affects not only the top, but also all other parts of the structure of a residential building and other buildings. Not without reason, when designing the foundation, it is necessary to decide in advance on the choice of the roof.

Roofing from profiled sheet

Currently, one of the most common roofing materials is a profiled sheet, which is produced galvanized or followed by a polymer coating. TO distinctive features profiled sheet will include the following parameters:

High corrosion resistance;
As a result, a long (more than 15 years) service life;
Easy installation even without the necessary qualification;
Small sheet weight (weight 1 m 2 is 4-5 kg).

Since this roofing material does not exert a high load on the rafter system, the distance between the elements is chosen as much as possible for a particular angle of inclination. In addition, the profiled sheet does not require high strength characteristics from the roof lathing. All this together allows minimizing the total load on the foundation and walls.

Roofing from a metal tile

The second common type of steel roofing materials is metal tiles. This type of profiled sheet, which successfully imitates natural clay material, but with a lower mass (10 or more). A feature of the rafters under the metal tile is the smaller section size.

When choosing at what distance to install the rafters, first of all, you should be guided by the dynamic load. Like a profiled sheet, a metal tile is not demanding on dimensions. rafter legs and is well mounted on a crate of an inch board of softwood. All this makes metal roof low-cost.

Rafter system for ondulin

In the 21st century, corrugated sheet materials were replaced by a more durable and lightweight analogue - ondulin. Among others - the most lightweight material. The weight of the sheet does not exceed 6 kg.

The small thickness of ondulin sheets at slope angles of less than 15 ° requires the construction of a continuous crate of plywood sheets, for example, which will require an appropriate rafter pitch. This should be taken into account in the calculations.

slate roof

Not so long ago, a wavy material from an asbestos-cement mixture, called slate, was widespread. High mass and fragility are the main disadvantages, however, even today he finds his fans in the construction of various outbuildings.

A high mass, comparable to the weight of a clay tile, will not allow the use of the same truss system as under a metal tile. Building codes defined minimum angle slate roof slope of 22 degrees or more. Otherwise, the load from the material itself and the truss system with the crate exceeds valid parameters. The step of the inclined bars, as well as their cross section, are selected individually in each case.

Polycarbonate roof

In recent years, more and more often on the roofs of verandas and gazebos, an artificial polymer material, polycarbonate, has been used. Produced in two versions - monolithic and honeycomb. The first in its properties is similar to ordinary quartz glass, but significantly exceeds it in strength. The second one has less mechanical properties, but high thermal insulation and light transmission.

Cellular polycarbonate is standardly much lighter than a monolithic counterpart. It is used as a roof without the use of lathing, provided that the step does not exceed ½ of the width of the sheet of material. The high strength of the monolithic analogue also makes it possible to avoid elements transverse to the rafters. Sufficient flexibility allows you to cover semicircular roofs on metal frame, the step of which does not exceed 0.9 meters.

Thematic material:

Rafters under a soft roof

The original pattern can be obtained through the use of soft roofing materials, which are spread with an adhesive layer. They are installed on a continuous crate made of plywood or OSB. The step of the rafters should allow you to fix the sheets, so it is chosen as a multiple of ½ of the width. Given the standard dimensions of plywood 1520x1520 mm, the center distance between the rafters will be: 1520: 3 = 506 mm.

Rafter step for insulation

The installation of residential under-roof spaces is often combined with the laying of insulation sheets in the rafter gap. The most common plates with dimensions of 600x1000mm. These parameters are used as starting points.

Rafter pitch calculation scheme

According to building codes, the pitch of the roof rafters is in the range of 0.6 - 1 meter. Its final calculation is performed according to a simple formula, depending on the total length of the roof. For the calculation, you must perform the following list of actions:

determine how much distance should be between the rafters for your specific building conditions. According to the reference book, the magnitude of wind and snow loads in the area is determined.
the length of the roof is divided by the desired distance by adding one. The result will be equal to the number of rafter legs that are installed on one roof slope. If the value is not an integer, it is rounded off.
the length of the roof is divided by the number of rafters calculated above, we get the final step in meters.

For example, with a slope of 30 degrees, the maximum distance between the rafters of a gable roof under a metal tile is 0.6 measure. The length is assumed to be 16 meters. Consequently:

16:0,6+1=27,66;
rounding the result, we get 28 rafters per slope;
16:28 \u003d 0.57 meters - the center gap of the rafter legs for these specific conditions.

As you can see, the calculation technology is not complicated, but this is just an approximate scheme. Taking into account many other parameters mentioned above can make certain adjustments.

The distance between the base of the roof slopes is not a constant value and depends on the following components:

type of roof;
slope angle;
the type of roofing material to be installed;
rafter section dimensions.

Before proceeding with the process of erecting the upper structure of the house, a calculation should be performed by determining the optimal distance between the rafters.

Gable roof rafter pitch

The most widespread in our country are gable roofs. They are a structure that has two parallel planes, with an angle of inclination relative to the horizon from 20 to 50 degrees.

With an insufficient slope of the gable roof in snowy areas, there is a danger of accumulation of large snow masses, which can lead to the destruction of the structure. An increase in the slope angle in regions with a predominance of strong winds is also fraught with a high load and the risk of breaking not only the roof, but the entire structure as a whole.

Mansard roof truss system

Most private houses have an exploited under-roof space called an attic. This design is characterized by an increased height of the slope, which is caused by the need to create a living space of a comfortable height. As a rule, the slopes of the mansard roof are broken, having a varying angle of slope. For their installation, a double truss system is used.

Rafters in a shed roof

For outbuildings and some private houses, roofs with one slope are used. Due to the limited angle of inclination, high pressure is exerted on them. Experts recommend using lumber of increased cross-section for the rafters of a single-pitched roof, with the installation of a minimum step from each other.

Hip roof truss system

The dependence of the pitch of the rafters on the roofing material

In addition to variable snow and wind loads, a constant (static) one also acts on the roof, the force of which depends on the roofing material used. It is no secret that different types of roofs have their own weight, which can differ by 10 or more times.

Roofing from profiled sheet

Currently, one of the most common roofing materials is a profiled sheet, which is produced galvanized or followed by a polymer coating. The distinguishing features of the profiled sheet include the following parameters:

High corrosion resistance;
As a result, a long (more than 15 years) service life;
Easy installation even without the necessary qualification;
Small sheet weight (weight 1 m 2 is 4-5 kg).

Roofing from a metal tile

When choosing at what distance to install the rafters, first of all, you should be guided by the dynamic load. Like a profiled sheet, a metal tile is not demanding on the size of the rafter legs and is well mounted on a crate made of an inch coniferous board. All this makes a metal roof low-cost.

Rafter system for ondulin

slate roof

A high mass, comparable to the weight of a clay tile, will not allow the use of the same truss system as under a metal tile. Building codes define a minimum angle of slope for a slate roof of 22 degrees or more. Otherwise, the load from the material itself and the truss system with the crate exceeds the permissible parameters. The step of the inclined bars, as well as their cross section, are selected individually in each case.

Polycarbonate roof

Cellular polycarbonate is standardly much lighter than a monolithic counterpart. It is used as a roof without the use of lathing, provided that the step does not exceed ½ of the width of the sheet of material. The high strength of the monolithic analogue also makes it possible to avoid elements transverse to the rafters. Sufficient flexibility allows you to cover semi-circular roofs on a metal frame, the pitch of which does not exceed 0.9 meters.

Thematic material:

Rafters under a soft roof

Rafter step for insulation

Rafter pitch calculation scheme

determine how much distance should be between the rafters for your specific building conditions. According to the reference book, the magnitude of wind and snow loads in the area is determined.
the length of the roof is divided by the desired distance by adding one. The result will be equal to the number of rafter legs that are installed on one roof slope. If the value is not an integer, it is rounded off.
the length of the roof is divided by the number of rafters calculated above, we get the final step in meters.

For example, with a slope of 30 degrees, the maximum distance between the rafters of a gable roof under a metal tile is 0.6 measure. The length is assumed to be 16 meters. Consequently:

16:0,6+1=27,66;
rounding the result, we get 28 rafters per slope;
16:28 \u003d 0.57 meters - the center gap of the rafter legs for these specific conditions.

As you can see, the calculation technology is not complicated, but this is just an approximate scheme. Taking into account many other parameters mentioned above can make certain adjustments.

The roof is one of the main elements of the house, so you should pay special attention to the correct calculation of the roof frame. Which will serve as a skeleton in your home. Incorrect calculation of all loads can lead to disastrous results in the form of deformation of the roof with its subsequent collapse.

Before proceeding with the installation of the roofing, it is necessary to calculate the truss system, which will depend on the material used, construction, and climatic conditions.

What you should pay attention to before making a calculation

Before starting the construction of the roof, it is necessary to choose the type of truss system. Then calculate all the loads that will fall on the roof. The main loads include the weight of the frame, roofing material, insulation, ceiling, and temporary loads are taken into account, among which are the weight of the snow cover, possible gusts of wind, the weight of a person during the installation and operation of the roof.

The distance between the rafters is calculated based on the selected type of rafters and the material with which the roof will be covered.

Types of rafters

When building roofs various designs use hanging or layered rafters. Sloped - used when installing one- or two-slope roofs. They have two points of support - load-bearing walls or bearing wall and ridge beam. Hanging rafters are used when it is necessary to cover large spans or create a sloping roof. In this case, the rafters rest with one end on the wall, and the other on the opposite rafter. The quality of the material from which the frame is made will directly affect the reliability of the entire roof.

Material for rafters

Currently, wood and metal are used. wooden beam or a log is used in the construction of residential buildings, garages and other buildings. Reinforced concrete or metal rafters are used in the construction of industrial facilities, shopping centers, where wide spans are needed.

Method of calculation

The distance between the rafter legs is called the pitch of the rafters. It should not exceed one meter, and the minimum value - 60 cm. Before making a calculation, it is necessary to measure the size of the roof slope. Then we divide the obtained value by the approximate value of the step between the rafters. One is added to the result and rounded up to the next whole number. So we find out the number of rafters that we need. In order to find out the exact distance between the rafters, for this we need to divide the length of the roof bevel by the number of rafter legs.

For greater clarity, consider an example calculation:

roof bevel length - 28.5 m

the step between the rafters is chosen equal to 80 cm

add one to the resulting number: 35.625 + 1 \u003d 36.625

as a result, we get that we need 37 rafter legs

the exact step of the rafters will be: 28.5 / 37 = 0.77 m

This is a general calculation method that requires adjustment depending on the roofing material.

The dependence of the pitch of the rafters on the material of the roof

The most common roofing materials are slate, metal tiles, corrugated board, ondulin, soft roofing.

Roof truss structure for slate roofs

Slate is widely used as a roofing material, due to its low cost, resistance to temperature extremes. Due to the severity of the material, it is necessary to install a powerful truss system. The distance between the rafters in this case will depend on the cross section of the timber. The optimal value is a distance of 80 cm, which will allow not only to withstand increased weight, but also significant snow and wind loads. In this case, the crate is made with a board at least 3 cm wide. Depending on the type of slate, the crate is made continuous for smooth sheets or sparse for wave ones.

Important: the slate must have at least three support points along the edges and in the center.

Step between rafters for metal tiles

Metal tiles are becoming more and more common among roofing materials. Which is characterized simple process installation, and also help to create your own unique look for your home. Sheets of metal tiles are lightweight, which allow you to increase the distance between the rafters from 600 to 950 mm, with a beam section of 150x50 mm. The crate in this case will depend on the pitch of the sheet wave. So for a wave of 350 mm, a distance between the boards of 30-40 cm is possible.

Important: on the overhangs of the cornices, the edges of the bevels, the step of the lathing is made minimal for greater reliability of the roof.

Rafter pitch under corrugated board

Decking is a galvanized steel sheet coated with a special coating that protects it from the harmful effects of the environment. Big choice color solution, corrugation width, will allow you to create a reliable and aesthetically attractive roof. The step of the rafters under the corrugated board will directly depend on the characteristics of the type of profile used, the angle of the roof, its configuration. You should also take into account the fact that the crate under the profiled sheet is attached perpendicularly. The rafter system is made of beams with a section of 50-75 mm or from a board 20-50 mm thick and no more than 15 cm wide. sparse - the distance between the boards is 50-75 cm. The step of the rafters under the corrugated board is calculated according to general scheme and is 60-90 cm.

Step of roof rafters from ondulin

Ondulin is a wavy sheet that has high strength and durability. With such a roof, the truss system is made of pine boards with a section of 50x200 mm, in increments of 60-90 cm. A sparse crate of 40x50 cm is made from above.

Important: if the roof has an angle of inclination greater than 50 degrees, then the crate must be solid.

Determining the pitch of the rafters for a pitched roof

A shed roof is simple and does not require any special installation skills from you. Most often it is installed on garages, baths, extensions. The roof frame consists of beams that rest on the walls of the building. The distance between the rafters of a shed roof will depend on the length of the rafters. Here you should correctly approach the choice of the section of the beam, since the greater the distance, the greater the load on the rafters. For the correct selection of the pitch of a shed roof, use the data from the table:

The distance between the rafters for a gable roof

The gable roof is the most common, not only because of the simplicity of the device, but also because of its high reliability. Rafter step gable roof calculated according to the general scheme. If the bevels are the same on both sides, then one part can be calculated. To do this, we determine the angle of inclination of the bevel, here you should take into account the material with which you will cover the roof. So at an angle of 45 degrees or more, you can use all types of coatings. For slate, tiles, the minimum angle of inclination is 22 degrees, for corrugated board and soft tiles- 12 degrees, for metal tiles - 14 degrees, for ondulin - 6 degrees. The length of the rafters for a gable roof is calculated using the Pythagorean theorem, in which the length is the hypotenuse, and the height of the roof and half of its width are the legs. If the spans are more than 6 meters, then the rafter system is additionally reinforced with struts and headstocks, which will not allow the rafter legs to deform under the weight of the roofing material.

The distance between the rafters (rafter legs) is called the pitch of the rafters. When arranging the roof, it is customary to use a rafter pitch of no more than 100 and at least 60 cm. The reliability of the roof structure depends entirely on how correctly the distance is calculated.

Incorrect determination of the loads on the rafters and the parameters of the materials used as them can cause deformation not only of the roof, but of the entire building. The roof can collapse and cause the destruction of the walls. Given this, the calculation of the design of the truss system must be given the same close attention as common project building.

Method for calculating the distances between the bars

moving along the eaves of the slope, measure its length;
divide the resulting number by the selected step (from 60 to 100 cm);
add 1 to the resulting quotient and round the number up.

As an example, take a slope 30 m long and a distance between the rafters of 0.6 m.

50 + 1 = 51 - 51 rafters are required to build a roof.

Then we determine the step between the bars, which will be used as a supporting structure:

30: 51 \u003d 0.58 m - the distance between the axes of the bars that will be installed on the roof slope as rafters.

This example shows the general methodology for calculating the supporting structure, but does not take into account the specifics of a particular roofing material. Experts recommend calculating the distance based on the characteristics of roofing.

In addition, calculations should be performed taking into account the materials from which the truss system of the house will be made. Here the step largely depends on both the type of material and its dimensions.

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The specifics of laying rafters under ceramic tiles

Despite the fact that ceramic tiles are one of the elite and environmentally friendly roofing materials, their laying is associated with certain difficulties. And the main one is a large mass. Thus, the weight of a ceramic tile is almost 10 times higher than the mass of a metal tile. And this means that for each m 2 of the structure, pressure from 40 to 60 kg will be exerted. These conditions imply the creation of a reinforced carrier system that can withstand the weight of the roof.

To create a truss system for a roof made of ceramic tiles, a beam with a cross section of at least 5x15 cm, and preferably 6x18 cm, is usually used. The moisture content of the wood should not exceed 15%.

The distance between the bars depends on the slope of the slope and the length of the rafters. So, the steeper the roof, the greater the distance between the rafter legs. If, with a slope of 15 °, the step is 80 cm, then with a slope of 75 ° it will be 130 cm. Long bars will be located at the maximum distance from each other, and short ones at the minimum.

In order for the installation of ceramic tiles to be carried out correctly, the step of not only the rafter legs, but also the crate is important. When creating a house structure, it is required to take into account the parameters of each roofing element (in this case, tiles). Typically, a tile tile does not exceed a length of 40 cm, and during installation forms an overlap with the previous row of about 9 cm. This determines the pitch of the crate, which should be at least 31 and not more than 35 cm.

Also, this indicator can be determined as follows:

the length of the bottom row is subtracted from the length of the slope;
then the distance between the first row of the crate and the last rafter is taken away.

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The specifics of the installation of the supporting structure under the metal tile and corrugated board

Installation of a metal tile does not require strengthening of the supporting structure due to its low weight. The wood will not resist the loads exerted, which means that the step between the bars may not be wide. So, with metal roofing, the rafters can be located at a distance of 60-95 cm from each other.

Decking is another roofing material that is lightweight. And according to other characteristics, the corrugated board is as close as possible to the metal tile. Therefore, the step of the rafter legs is similar to the above - from 60 to 90 cm.

Distance parameters define characteristics building materials. For example, if a plank with a width of less than 10 cm is used to equip the structure on the roof, the distance should be reduced to 50 cm.

Do not forget about the distance between the elements of the crate, which can be from 0 to 400 cm. The pitch of the crate is selected taking into account the grade of the profiled sheet and the slope of the slope. For example, a profiled sheet of grade S-21 with a thickness of 0.5 to 0.7 mm with a roof slope of more than 15 ° should be attached to the crate, the step of which will be no more than 65 cm.

The shed truss system came to us from the USA and Europe. Residents using it noted reliability and cheapness, so the popularity of this type spread very quickly. Despite the fact that a small amount of wood was required for the construction of one slope, few people dared to build such a construction. The fact is that most developers considered such a system too simple for residential buildings, while the other part simply did not know how to build it to prove the opposite. In this article I will try to explain to you how to easily and quickly create such systems and correctly select the pitch of the rafters of a pitched roof.

Basis of calculation

Despite its simplicity, one slope must meet all the installation rules. After all, if serious mistakes are made at the same time, then the roofing will deform, which will inevitably entail not only leaks, but also the collapse of the entire roof.

To achieve maximum stability of the roofing system, it is necessary to pay attention to four components:

Reliability of fastening of the rafter legs to the support beam and ridge;
Proper selection of auxiliary parts for the truss system;
Durable lumber and auxiliary elements;
rafter step.

Do not think that by observing only four points you will achieve the most stable design. To do this, you will have to use all known methods and technologies.

Calculation values

You can’t perform calculations without knowing certain indicators, right? Therefore, before starting, you need to make sure that you have four basic values.

Roofing material parameters

Step of rafter legs

Rafter slope

In addition to all these indicators main task of any project is the calculation of the maximum allowable load on the roof. It includes quite a lot of values, and here is a list of elements whose mass is especially important in the calculation:

rafter legs
crate
roofing cake

If you are far from the construction industry, then you will have to remember that the calculation of the maximum roof load consists of two parts. The first one takes into account all the materials used, and the second one contains the snow load of your region. Its meaning is written in a special reference book, which you can easily find on the net.

But even on this, the indicators will not be accurate, because you forgot about the wind load and the weight of the worker himself, who will conduct installation work and subsequent maintenance (repair, cleaning).

When developing a project by a construction organization, they use complex formulas of strength of materials, so if you don’t want to bother with this, you can use the recommendations of experienced people.

How to calculate the required distance between the rafters

The distance between the rafters of a shed roof largely depends on the previously calculated maximum possible step. To determine this value, you will need to have a total load value, roof parameters and data on the wood of the rafter legs.

You can calculate the optimal step of the rafter leg using the following method:

First of all, you need to find the total length of the roof. This value must include any ends and overhangs;
The resulting value is divided by the maximum allowable distance between the rafters;
The answer is rounded up. This number will indicate the number of spans;
Next, we take the value of the length of the roof and divide it into spans. So you will find the optimal step;
And to find the number of rafter legs, you need to add one to the spans.

This rule works for the vast majority of roofs, but there are those that cannot be calculated in this way. If you have just such a case, then you will have to acquire an additional rafter on one of the ends.

Rafter system depending on the roofing

It's no secret that the greater the mass of the roofing, the greater the number of rafter legs must be installed. Most manufacturers of this material in the instructions for their product indicate the optimal number of rafters and their dimensions.

You should not blindly trust these instructions, only if you do not live in the central strip of Russia, because they were written specifically for this territory. Before developing a drawing, it is necessary to carefully study the prevailing winds and draw a kind of rose, which will be a guide for future construction.

It is worth noting that in regions of the country where a large amount of precipitation in the form of snow falls, it is best to create steep roofs with a slope of 35-45 degrees. This will provide fast natural gathering snow cover from the surface.

In most cases, the truss system of private houses is created from logs with a diameter of 12 to 22 centimeters, timber or boards with thicknesses from 40 to 100 and widths from 150 to 220 millimeters.

Rafter system for corrugated board

Roofing corrugated board is a fairly light material and at the same time has good strength characteristics. Therefore, as rafter legs, you can use lumber of a small section, but with a frequent step: 0.6 - 1.2 meters. The roof slope should be at a slope of 12 to 45 degrees.

The required section can be selected based on the span distance between the supports. If the distance is about 3 meters, then the section can be taken 40x150 millimeters, at 4 meters this value increases to 50x180 millimeters, and at 6 meters it is necessary to use lumber whose section is 60x200 millimeters.

By the way, the crate in this matter also plays an important role. In the case when the rafter step is a decent value, you will have to use wider boards. For example, for a step of 0.6 meters, elements with a section of 25x100 millimeters will be needed, and for 1.2 meters - 40x100.

The crate for corrugated board is arranged discharged method, and the step of its elements should be 50-80 centimeters. However, these values \u200b\u200bmay go beyond due to the characteristics of the roofing itself. You can also find tips on how to arrange these parts in the instructions that came with the purchased material.

Rafter system for ceramic tiles

Ceramic tiles are a unique roofing material. It is made of clay, which makes this material very heavy. Designed truss systems in without fail must follow the following requirements:

In the roofing sphere, there are only 3 types of crates. One of them can be arranged at an angle of 12-60 degrees, and the other two at an angle of 20-45 degrees. As elements of the crate for clay tiles, you can most often see a beam with a section of 50x50 millimeters.

Rafters for metal tiles

Due to the fact that metal sheets have a much smaller thickness, you do not have to arrange a serious truss system. Therefore, you can safely follow the advice and recommendations of roofing material manufacturers.

It is worth saying a few words about the only nuance that will allow you to save some lumber. So, it lies in the fact that the minimum step of the crate can be increased to 1 meter. It has to do with size. sheet material. When a metal tile is tripled, then, as a rule, it is supported by a crate in only a few places, and with a rafter pitch of 0.6 meters, it is impossible to create an “economical” crate, so you have to change it along with the rafter system.

Rafter structure for ondulin

To date, ondulin has given way to more modern coatings, but despite this, developers whose roofs were laid with asbestos slate began to look at this material as a profitable alternative. It is made on the basis of bitumen and fiberglass, has a low weight and high quality.

The truss system for ondulin must comply with the following parameters:

The slope of the slope should be in the range from 5 to 45 degrees;
With a small slope, the step of the rafter legs should be minimal: 0.6 meters, and with a steeper roof, this distance increases to 0.9 meters;
With a sloping roof, say up to 10 degrees, it is necessary to arrange a continuous crate. To do this, it is best to use moisture-resistant plywood, OSB boards or edged board with a section of 30x100 or timber 40x50 millimeters.

As for the section of the rafter legs themselves, it is selected according to the same rules as for corrugated board.

Rafter system for corrugated asbestos-cement sheets (slate)

Surprisingly, everyone knows the roofing material called "slate", because the vast majority of private houses are covered with this particular product. Due to its rigidity and components, this material has a fairly solid weight, so it is necessary to follow the recommendations for the construction of the truss system so that it does not collapse even before the start of operation.

The low tightness of the finished plane does not allow the use of slate with a slope of less than 22 degrees, this will lead to leaks. If you cannot find any recommendations for the installation of asbestos-cement sheets (which is unlikely), then you can always use the instructions that came with ondulin;
The maximum possible slope of the rafters at slate roof- less than 60 degrees;
The optimal step of the rafter legs lies in the range from 0.8 to 1.5 meters. Here everything will depend on the load and cross-section of lumber;
As a rule, a wooden system for slate requires a slightly larger section of the legs than with a light roof. An example is the situation when the pitch of the rafters is 1.2 meters. For the rafters, you will have to take a bar with a section of 75x150 or 100x200;
As for the crate, its elements will also differ from the step of the rafter legs. If it is up to 1.2 meters, then a bar of 50x50 millimeters will do, and with a larger step - 60x60 millimeters;
The step of the crate beam should be selected so that one sheet is supported by 3 elements. The slate should extend beyond the edges by 15 centimeters on both sides. For example, if we consider standard sizes asbestos-cement sheet (175 centimeters), then you can use a crate step of 80 centimeters.

It is probably worth remembering that asbestos is harmful substance , therefore, when working with a material that contains its particles, safety precautions must be observed. Which states that the worker must wear personal protective equipment.

Rafter system of one and two slopes

IN Lately the shed roof is getting more and more sympathy. It is understandable, because materials are only getting more expensive, and you want to save money. Due to the simple design, this can be done. The rafter system of one slope is quite primitive. To do this, you just need to put the beams on the crown and secure. Of course, do not forget about the insulating material.

The maximum slope of a shed roof can be 30 degrees, and the span is 6 meters (this rule applies to lumber). The most optimal slope is 15-20 degrees. At this angle, the wind load will not cause much harm, but the snow cover will cause some inconvenience. The solution to this problem can be to place your building "downwind", which will allow it to remove snow mass from the roof naturally.

An alternative option for a single-pitched roof is a double-pitched one. It is a number of rectangles connected together with a Mauerlat and a ridge. It is worth noting one interesting fact. When the shape of a triangle approaches an isosceles one, its rigidity increases. In this regard, with a roof slope of up to 60 degrees, it is possible to expand the step between the rafter legs.

But do not flirt with calculations, because this can lead to an increase in windage and lumber consumption. The most optimal ramp slope for gable system- 45 degrees.

If you decide to build a roof yourself, then you will certainly need some tips that will not only make your work easier, but also increase the operational period of your roof as a whole.

Calculating the structure correctly is not an easy task, but even if it is done correctly, it can be broken if it is incorrectly fastened. Therefore, mounting the rafter legs in their places, do the work with all responsibility. To improve your skills, you can read information on the network, or invite a knowledgeable person to the facility;
The step of the rafter legs should not affect the thermal insulation in any way. It is worth remembering that the plates can vary slightly in size. Take advantage of this and push them as tightly as possible. In a hardware store, there are standard sizes of insulation boards of 60, 80, 100 and 120 centimeters;
For most roofs with a slope of less than 45 degrees, it is necessary to include the weight of the worker in the calculation. As for sharper roofs, this is not necessary, therefore, it is possible to reduce the pitch of the rafter legs by 20%;
Take advantage modern technologies and calculate your roof with online calculators. All you need is to enter the exact parameters;
Regulatory documents regarding wind and snow load you can find on the net or from the craftsmen at the construction site;
Any wood used for construction purposes should be dried as much as possible. This will avoid its deformation in the future.

The roof of a building is one of the most important elements of the entire building. If you start saving on a roofing pie, then soon you will face costly repairs that will affect not only this site, but the entire building as a whole. Therefore, if you want to get the maximum operating period from your comfort, then you should not use low-quality materials.