The step of the rafters of a gable roof: the dependence of the step of the rafters on the roofing material. How to determine the distance between the rafters of a mansard roof? Distance between roof rafters

Distance between rafters pitched roof is one of the most important parameters in its construction. It is this distance that affects the strength of the frame and the truss system, respectively, the strength of the entire roof also depends on it. To correctly determine it, it is necessary to make quite complex calculations. In this case, it is strongly recommended to contact an architectural studio for their implementation. Not correct calculations and, as a result, an incorrectly chosen distance between the slopes can lead to serious negative consequences, such as deformation of the supports of the truss system, deformation and violation of the integrity of the roofing, collapse of the roof. Therefore, during the design process gable roof it is extremely important to use the most accurate initial data, reference values \u200b\u200bmust be taken strictly in accordance with the specific conditions of the construction, and the calculation must be made according to the methodology indicated below.

The distance between the rafters of a gable roof is one of the most important parameters in its construction.

Primitive calculation method

Usually builders refer to the spacing between rafters as their pitch. Almost always, the rafters are separated by a maximum of 1 m (at the base), while the minimum allowable interval between them is usually within 0.5 m. The algorithm for calculating the required number of supports for the construction of a solid roof is as follows:

First, the length of the slope along the eaves of the roof is measured (actually the length of the wall parallel to the slope + the expected ledges).
The value obtained during the measurement is divided by the selected interval between the "legs" of the truss system. Next, choose the interval for which the "legs" will be divorced. For example, 80 cm. In this case, the denominator of the fraction will be 0.8.
The last stage: a unit is added to the resulting quotient, if the resulting number is not an integer, then it is increased to an integer, always upwards.

Such a simple calculation will allow you to determine the number of rafters, as well as the distance between the supports. It is important to remember that the values obtained will determine the number of supports for only one of the two slopes. When the count is completed, the longitudinal size of the slope is divided by the estimated number of truss supports. The result of this will be the exact distance between the supports. Consider one example: the length of the slopes of a gable roof (not total) is 20 m. Initially, a step of 0.75 m was selected. We make a preliminary calculation: 20/0.75 = 26.7. We add 1 to the obtained value, we get 27.7. Then we round up to a larger one and as a result we have 28 pieces. rafters. That is how many "legs" the rafter system of one slope will have. Next, we determine the exact distance between them: 20/28 \u003d 0.72 m. Using this simple technique, you can determine the minimum interval at which the rafters will be placed. However, it is also important to take into account what roofing material selected.

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If decking is selected

The professional flooring is though not heavy, but at the same time very flexible material. Therefore, for it, the minimum allowable step should be 0.5 m, and the maximum should not exceed 0.9 m. At the same time, the frame of the truss system must withstand not only the mass of the profiled sheet, but also the battens. For a profiled sheet, the crate is stuffed from timber or boards with a minimum size of 30x100, the average installation step of the crate should be 0.5 m (it depends only on the thickness of the sheet). The boards of the crate, which go to the eaves when stuffing the corrugated board, should be 1.5-2 cm thicker than the main crate. At the same time, it is important not to forget about the need for ventilation of the structure.

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Ceramic tiles

The main feature of this material is that ceramic tiles are very heavy. This is logical, because the raw material is ordinary clay, which has a large specific gravity. If we compare metal tiles and ceramics, then they differ in mass by more than 12 times. The weighted average pressure of such a coating is 45-70 kg per square meter of crate.

Ceramic tiles are very heavy, because the raw material is ordinary clay, which has a large specific gravity.

The frame with supports for such material should be made of perfectly dried timber, with about 15% moisture. For mounting, use bars approximately 50x150 mm (recommended 60x180 mm). The step of supports for ceramic coating will be in the range of 0.8-1.25 m. This value is greatly influenced by the angle of inclination of the slopes.

For example, if the angle is 15 °, the minimum interval is taken - 0.8 m. With a slope of about 45 ° - all 1.25 m. For this type of roofing material, specialists also calculate the length of the rafters (when calculating the interval between supports).

So, if the length is maximum for a particular roof, then the step value should be minimal. Short rafters require the largest possible interval between them. In this case, it is possible to move along the roof only if the rafter pitch is not more than 0.8-0.9 m with a slope of 45 °. One should also not forget about the need for ventilation of such a design.

For this, holes in the insulation are usually provided, the diameter of which is in the range of 9-12 mm. The process of erecting a rafter system under a metal tile is similar to the process of building rafters for other types of coating.

It is important to remember that in addition to carefully calculating the required number of rafters, the step for the crate should also be calculated.

It differs depending on the type ceramic tiles. For example, the length of a ceramic tile tile is 0.4 m, while the joint overlaps 0.5-0.9 m. In this case, the sheathing step will be 0.31-0.35 m. It is important to remember that for each slope it is necessary make a separate calculation, since it is impossible to build an absolutely identical truss structure (even if it is the same according to the project): errors and inaccuracies in the assembly can give an error of 0.2 m.

A shed type of roof is rarely seen in private housing construction. Although, according to some, this is in vain, because the installation pitched roof it is much easier than installing a gable. On the other hand, such a roof design will not be able to keep the heat in the room so well. That is why shed roofing is most often used for building a garage, country house or barn.

True, if the work on thermal insulation is correctly performed, then the structure may well be warm. In this case, a living room is made under a pitched roof. Let's look at the advantages of a shed roof, what types of truss systems exist, how the design is calculated. In addition, we will consider how to install this type of roof.

Pros and cons of a shed roof for a house

Beginners in the construction business will be delighted that such a shed construction is quite simple and can be done by hand. True, it is impossible to call the work the easiest, but with detailed instructions a pitched roof will be created. But before considering design features roofing, you need to find out its features and advantages. They characterize this type of roof.

Advantages of a pitched roof:

Profitability. For the device of the roof, a lot of building materials are not needed, on which the bulk of the funds are spent.
The simplicity of the truss system and the shed structure as a whole. The best thing for beginners. Installation will be easier than with a gable roof.
The building will have a small weight. This means that there is less load on the walls and foundation.
Thanks to this shape, a shed roof perfectly resists wind loads, as well as the weight of snow that accumulates on the surface.
The angle of inclination is very different, depending on the needs. It varies from 5° to 45°.
If you make the angle of a shed roof small, then it can be used for various purposes. For example, if this is a barn, then install a tank for heating the liquid. If this is a living space, then on a shed roof you can equip a great place to relax. Alternatively, install solar panels as an alternative power source.
The versatility of a one-slope building. It is covered with almost any material available on the market. It all depends on the operating conditions and the chosen angle of inclination.

Despite all its advantages, a shed roof has its drawbacks. This is not surprising, since nothing is perfect, but it is better to know about the cons and use them profitably.

Minuses pitched roof:

The first concerns insulation. There is no more space with an air gap under the structure, so the issue of insulation should be taken more seriously. If you do not make thermal insulation of the structure, then in summer the attic will be too hot, and in winter, on the contrary, it will be supercooled. In either case, the temperature (high or low) will be transmitted to the house. Correct calculations and high-quality insulation will help eliminate this;
when creating a ceiling immediately under the roof, made at a slight angle, the house will not have an upper air gap and an attic. And in this case, living space cannot be organized;
due to a slight slope, which reaches from 5 to 10 °, snow and moisture will accumulate on a shed surface.

Despite all the obvious disadvantages, a shed roof is an ideal option for creating a garage and other buildings on the site.

Calculation of the construction of a single-pitched roof

This is the first stage before the installation of the truss system. It is recommended to draw up detailed plan or a drawing that will be guided by when working. To create this schema, you need to highlight the following data:

the total width of the roof construction, as well as the length of the spans that is formed between the bearing walls;
slope angle, desired or obtained;
the length of the single-pitched roof;
selected roofing material;
what is the height and width bearing walls.

Note! When a shed roof is created for a barn, garage, or country house, you can simply raise the front wall of the structure above the back.

As a result, the angle of the slope will depend on the height of the rise. The second option involves the creation of supports, on which the run will fit. The second way allows you to save building materials.

For drawings, you need to know the following nuances:

The drawing of the future shed roof should have all the necessary information about the elements. The dimensions, distances between them, fastening features, etc. are indicated. Below is an example of such a drawing of a pitched roof.

Choosing the corner of a pitched roof

The angle of the slope is chosen taking into account the fact that the resulting roof forms a triangle, one corner of which will always be right. The legs are the floor beams and the gable part of the building, and the rafters serve as the hypotenuse. This is clearly seen in this diagram.

The designations are as follows:

Lc - the length of the rafter used;
Lbc - our leg, indicating the height of the pediment from the floor beam to the roof plane;
Lsd - the width of the building;
A - the selected or desired angle of a pitched roof.

Given the basic values, it is possible to calculate all the parameters of a single-slope structure. There is a formula for this. The first is used when the width of the building and the planned height of the pediment are taken as the basis. In this case, the formula is:

When you have decided on the angle of the shed roof, then you need to calculate the future height of the gable. For this, the formula is:

In this case, the length rafter legs roofing is calculated as follows:

Note! This length of the rafters does not take into account the canopy from the rear or the facade of the room.

Many criteria influence the choice of slope angle. The main one is the choice of roofing material. Each of them is recommended to buy for a particular angle of inclination. Here are recommendations for popular roofing materials:

For the installation of corrugated board, the slope must be at least 8 °.
When using metal tiles, you will need to make a roof with an angle of inclination of 30 °.
For a slate device, indicators from 20 ° to 30 ° are needed.
As for rolled roofing materials (roofing material, shingles and soft roof), then the angle of inclination should be 5-7 °, not less.

Advice! A roof without a heating system in an area where there is a lot of snow in winter, a shed type roof with a slope of 40° is ideal, regardless of the roofing material. So all precipitation will quickly descend from it.

Varieties of the truss system of a shed roof

There are three options for creating a truss system. The choice of design depends on the size of the room and its type.

Now that we have dealt with the design of the truss system and learned its types, we can consider the process of creating a shed roof.

Installation work on the creation of a pitched roof

Having on hand the drawings and the selected type of system, you can get to work. You will also need the appropriate tools and lumber. The installation of the truss system is performed as follows:

For safety, the building should be covered with beams. They are placed on the wall. To extend their service life, roofing material is glued to the wall. It will protect the beams from moisture and decay. You need to position the floor sticks in the same way as the rafters. Fastening pitch -500-800 mm.
Mauerlat is laid on top of the beams. This is a massive beam that will serve as a support. It fits on the back bottom wall of the building.
To safely move around the roof, flooring is laid on the floor beams from wooden planks. He is temporary.
Now you need to build a gable wall. It is made from the same material as the building itself. You can use lighter material. For example, if the walls are brick, then the pediment rises by means of bars or boards.
Floor beams must be covered with waterproofing and walled into the wall. The pediment rises to the chosen height, according to the drawings.
On the finished pediment, you can fix the Mauerlat. It turns out that two Mauerlat are parallel to each other.
Markings are applied to the lower wall for attaching the rafter legs. The fastening elements themselves are fixed.
To firmly fix the rafter, based on the drawings, grooves are cut on it. This a good option mounts. The grooves are in two places, top and bottom, to enter the Mauerlat. There are other methods of fixing the rafter leg, as shown in this photo.
After that, the legs are fixed with special corners and fasteners. From above, at the pediment, the legs are screwed rigidly. But the lower part is made depending on the chosen truss system of a pitched roof. It can be rigidly fixed or made sliding.
There is a certain sequence of inserting rafter legs. First, the extreme elements of the truss system are mounted. A cord is stretched between them, serving as a guide and level for subsequent rafters. Do not forget that the step of the rafters corresponds to the step of the floor beams.
The rafters that are already installed are connected to the floor beams through racks, struts and other elements to give them stability. We talked about them above. Fixation is carried out with metal corners and staples.
Tip! If you want to lengthen the rafters and bring them out of the wall, then “fillies” are attached to the bars. So you can protect the adjacent part of the structure from precipitation.
When the construction of a shed roof is ready, you can begin to insulate and create a roofing pie.

The photo shows what layers the correct insulated shed roof should consist of.

Insulating material is laid between the rafters. He has to hold on tight there. After that, a counter-lattice for ventilation is made on top. Fits on the counter-lattice waterproofing film. It protects the insulation from moisture, which can ruin it.

As for the crate for laying roofing material, it is selected depending on what kind of roofing material it will be. For example, a solid crate of boards or plywood is needed when installing soft tiles and other roll materials. If metal tiles, corrugated board, slate, ondulin and other types of hard roofing are used, then the crate is done in a row. The step depends on the roofing material.

And in order to protect the insulation from the inside of a shed roof, you need to sheathe it with a vapor barrier film. Now we can say that the shed roof is completely ready.

Note! If a shed roof is made for a barn or other non-residential structure, then it is not necessary to insulate it. It is better to spend them for another purpose.

Conclusion

Creating a roof, whether it is a gable or single-pitched, is a dangerous, time-consuming and responsible process. That is why caution is required and strict adherence to the instructions for creating a structure. Only then can the best result be achieved.

The distance between the rafters is a fundamental parameter on which the strength and reliability of the roof structure, its service life, and the possibility of using certain roofing materials depend.

The strength and service life of a roof depend on many factors: building materials, climatic conditions, crate reliability.

But the supporting structure of the roof is the foundation on which the entire structure rests.

The rafter system must be accurately calculated, correctly mounted and reliably protected from destructive external influences.

General scheme for calculating the rafter step

The truss system is the supporting structure of the entire roof. It consists of rafter legs, vertical struts and inclined struts.

Each rafter is located at a certain distance from the next - this distance is called the "rafter step".

The strength of the roof structure, the maximum allowable load per square meter and the materials that can be used for roofing depend on it.

According to GOSTs, the minimum allowable value of the rafter pitch is 60 cm, the average is more than 1 m.

To determine the approximate pitch, you can use the following formula: D / (D / m + 1), where D is the length of the roof from ridge to ridge, m is the approximate rafter pitch.

All results must be rounded up to the nearest higher integer. It is obvious that such a formula serves only for approximate calculations.

To determine the exact step size, the following factors must be taken into account:

own weight of the truss system, i.e. the materials from which it is made;
the weight of the material with which you plan to cover the roof;
weight of additional heaters, seals, hydro and vapor barrier systems;
crate weight;
weight finishing materials attic
climatic loads (wind, snow accumulation).

In addition to the loads listed above, the roof must be capable of supporting the weight of at least one adult person, so that in the event of a repair or installation of an antenna, the installer can safely climb onto the roof.

If you plan to install a chimney, then its location must be included in the calculations initially so that in the future it will not be necessary to remove part of the roof and install additional support points.

Shed and gable roof: the difference in truss systems

For a shed roof, building a truss system is quite simple. Most often, the rafters are laid directly on the crown, without the use of additional supports and supporting structures.

That is why the maximum angle of inclination of a shed roof is limited to 30 degrees: the absence of additional load-bearing structures and supporting beams means that the entire load falls on the walls of the building and the foundation.

The optimal angle of inclination is 15 - 25 degrees. The maximum allowable span of rafters does not reach 6 m.

When building a shed roof, be sure to take into account the direction of the wind and the possible additional load from the weight of snow accumulated on the roof.

For houses located in regions with strong winds and low rainfall, you can guess a slope angle at which the roof is cleared of snow due to gusts of wind.

A gable roof is a system of two inclined slopes connected by a ridge. One of the main advantages of this design is the ability to more evenly distribute the load between the truss system and the load-bearing walls of the building.

In addition, the gable frame allows you to lean the rafters on each other, which gives it additional strength.

The overall strength of the roof structure increases as the slope angle approaches 45 degrees. It is this slope that is considered optimal for regions with heavy rainfall.

With an increase in the angle of inclination, on the one hand, stability increases significantly, so you can take a larger rafter pitch.

On the other hand, the windage of the roof increases, so for windy regions the optimal angle of inclination does not exceed 20 degrees.

Rafter system under slate

Despite the emergence of a large selection of modern roofing materials, the classic version - slate - is still very popular, mainly because of the cheapness and ease of installation.

The distance between the roof rafters under the slate is calculated taking into account the characteristics of the material: the slate is quite fragile, but at the same time it is able to withstand heavy weight loads.

The permissible range of the rafter step for slate is from 80 cm to 1.5 m. The average step length, 120 cm, is most often used.

Since the slate itself weighs quite a lot, the material for the supporting structure must be chosen durable, for example, bars with a cross section of at least 75 mm by 150 mm.

The length of the rafter pitch and the thickness of the crate are interrelated: the more durable the crate you plan to install, the smaller the pitch, and vice versa.

The slate sheet has a standard length of 175 mm, the lathing pitch is selected so that each slate sheet has at least three support points (one in the center of the sheet and two closer to the edges).

The step of the lathing depends on the degree of the slope of the roof: 63 - 67 cm is enough for a flat one- or two-slope roof. The minimum gap for a steep roof is 45 cm.

You can set the exact length of the rafter step for slate only by making accurate measurements and calculating total weight all roofing materials.

Do not forget to take into account the weather conditions (the possibility of snow accumulation, strong gusts of wind) and the load additional equipment(antenna or chimney pipe). If an attic is equipped in the attic, then consider the weight of the heaters.

The nuances of the system for metal tiles

Metal roofing is one of the most popular roofing materials on the market. It is unpretentious in handling, durable, looks beautiful.

In addition, metal tile is one of the lightest roofing materials (only 35 kg per square meter), it can be laid on a fairly light support, thereby reducing the load on the walls of the building and the foundation.

The average distance between the rafters under the metal tile is 60 - 95 cm for a gable roof with a slope of 20 - 45 degrees.

The size of the bars is chosen taking into account insulating and waterproofing materials. For a simple roof made of metal, a section of 50 - 150 mm is sufficient.

But in most cases, to create mansard roof under the metal tile, you will have to lay a heater with a thickness of 150 - 200 mm.

Taking into account the weight of the insulation, the truss system should be more durable, the recommended size of the bars increases to 200 mm by 50 mm.

When calculating the distance between the rafters, consider not only the length of the metal sheets, but also the insulation.

At correct location rafters, you can significantly save on timber.

Do not forget about the peculiarities of mounting a roof made of metal: this material does not pass air well, as a result of which condensation often accumulates under the roof.

Fasten the top support of the truss system to the ridge run instead of the side part. This will create a small air gap, increase ventilation and help protect the roof from destructive moisture.

Rafter system for corrugated board and ondulin

Distinctive feature corrugated board is lightness and rigidity, therefore, as in the case of metal tiles, the requirements for the rafter system are not so high.

The distance between the rafters under the corrugated board should be in the range from 60 cm to 120 cm. The optimal section of the rafter leg depends on the span between the supports.

So, for a span of 3 m, a beam with a size of 40 mm by 150 mm is chosen, for a span of 5 m - a size of 50 mm by 180 mm.

What distance is permissible between the rafter legs depends directly on the cross-section of the bars: the larger the rafter step, the more durable the material must be used for the rafters. When choosing a step of more than 80 cm, increase the thickness of the bars by 20 - 25%.

Do not forget to take into account the weight of the crate under the corrugated board. The distance between the rafters of a shed roof of 60 cm will require a crate with a minimum cross section of beams of 25 mm by 100 mm.

With a rafter pitch of 80 cm, it is 30 mm by 100 mm, etc. The angle of inclination of the roof also plays an important role: with a slope of less than 15 degrees, it is recommended to lay a continuous crate under the corrugated board, which is much heavier than a sparse one.

Since both are relatively light in weight, the supporting structure can be light enough to reduce stress on the load-bearing walls and foundation of the building.

The higher the degree of inclination, the greater the distance between the rafters is allowed.

On a gable roof with a slope of less than 10 degrees, it is recommended to install a continuous crate, which increases the load on the roof structure.

In this case, it is better to use more thick timber 40 mm by 50 mm in size, and minimize the rafter pitch (60 cm).

truss system, undoubtedly, is the most important structural element of any pitched roof. The consequence of its improper installation can be not only the deformation of the roof, requiring expensive repairs, but also the complete collapse of the roof on the head of an insolvent builder.

The following four main factors influence the stability of the truss system to various loads:

fastening strength rafters to the ridge and Mauerlat;
correct calculation of the supporting structure for rafters, depending on the length of the span;
choice roofing material;
step between the rafters.

The topic of this article is the choice of material and pitch between the rafters, taking into account the intended type of roof.

What are the calculations based on?

When making calculations, four main indicators are taken into account:

design features of roofing material;

span length between supports;

rafter mounting angle.

The most important is the calculation of the maximum roof load, consisting of:

rafter weights,
crate weight,
weight of roofing material and insulation,
snow load (reference information unique to each region),
wind load (also reference information),
person's weight (if repair or cleaning is necessary, 175 kg/sq.m).

To carry out accurate calculations, experts use special formulas from sopromat, but when building a private one, you can use approximate recommendations.

Method for calculating the distance between the rafters

Accurate Distance Calculation between rafters is based on the results of a preliminary calculation of the maximum allowable step. To make this calculation, the total load, the roof structure and the material used on the rafter legs are taken into account.

Method for calculating the step of the roof frame:

Measure the length of the roof from end to end.
Received distance divided by the maximum step size.
The resulting value is rounded up to a larger integer.. This is the number of inter-rafter spans.
Divide the total length of the roof by the number of spans. This is the required rafter step size.
Add one to the number of spans.This is the required number of rafters.

For some types of roofing material it is desirable to use fixed distances between the rafters, in which case an additional rafter with a non-standard pitch is installed on one of the ends of the roof.

Rafter leg step depending on the material

Can be increased as the strength of the material from which they are made increases. Most often, for each roofing material, the step of the rafters required for it and the permissible sections of the rafter legs, taking into account the load, are indicated.

These recommendations are regional character and are applicable to the central strip of Russia and more southern regions. Before developing a drawing, you should definitely check the level of wind pressure and snow cover in your region, and adjust the pitch and / or cross section of the rafters.

In those regions where the snow load significantly exceeds the wind load, the use of roofs with a slope is recommended. 35 – 45 degrees.

truss system in private houses, it is most often made of logs with a diameter 12 - 22 cm, beam/board thickness 40 – 100 mm and width 150 - 220 mm. When calculating, it is possible to allow the use instead of logs of a certain diameter of bars of the same width, thickness 100 mm.

Rafter structure for corrugated board

Roof structure for ceramic tiles

Ceramic tiles has significant differences from other types of roofing materials, which must be taken into account when designing a truss systems for it:

5 to 10 times the weight resulting in doubling the weight of the entire roof. This leads to the need to use the frequent step ( 0.6-0.8 meters) and increased by 25% cross-sectional area of the rafters.
Fine-grained nature of the material. Increases the requirements for the accuracy of the installation of the transverse battens. The step of the sheathing beam, the permissible sections and installation angles are always indicated in the instructions for each specific tile model.

There are models of tiles designed for installation at an angle. 12 - 60 degrees, ordinary models are recommended to be mounted at an angle 20 - 45 degrees. For crates most often use timber 50x50 mm.

Roof structure for metal roofing

metal tile essentially a less rigid and lighter decorative option corrugated board, so the requirements for the rafter system, in particular for the recommended sections of the rafter legs, are largely the same.

feature roof structure under the metal tile can be called a significant reduction in the pitch of the crate, which should be equal to the length longitudinal wave(30 cm for most types). This leads to the need to reduce the distance between the rafters. up to 0.6 - 1 m, to reduce the cost of lumber for the crate. The angle of the roof slope is selected from 22 to 45 degrees.

Rafter structure for ondulin

Ondulin- slate based on fiberglass and bitumen, produced by only one manufacturer and has unified technological installation standards:

permissible mounting angle - 5 - 45 degrees;
distance between rafters - 60 cm at a slope angle of up to 15 degrees, up to 90 cm - at an angle of more than 15 degrees;
crate - solid plywood on a slope up to 10 degrees, board 30x100 mm step by step 45 cm on the slope 10 - 15 degrees, bar 40x50 mm step by step 60 cm on the slope above 15 degrees.

Given the low weight of the material, the cross section of the rafter legs is selected based on the same recommendations as for corrugated board.

Rafter construction under a covering from slate

Slate- traditional, rather rigid and heavy roofing material, fragile, but resistant to constant loads. Such properties change the recommendations for the optimal design of the truss system towards the use of more durable elements and increasing the step between them:

Due to low tightness, it is undesirable to use slate roofs with a slope angle of less than 22 degrees. If it is necessary to install such a roof, you can use the recommendations for installing an ondulin as an instruction, adjusted for the universal batten pitch - 55 cm.
Permissible angle for installing rafters under slate - up to 60 degrees.
The installation step is selected from 0.8 to 1.5 m, depending on the section of the rafter leg, the load and the presence of the crate material.
The material for the rafters is selected with a slightly larger section than for light roofs. For the most popular move 1.2 m a bar is taken with a section from 75x150 to 100x200 mm, depending on the length of the span between the supports.
Material for the crate selected in accordance with the distance between the rafters - timber 50x50 mm up to 1.2 m, beam 60x60 mm - 1.2 m and more.
Lathing step is selected in such a way that each sheet lies on three bars, and has an overlap on 15 cm with neighboring. Considering the standard sheet length 1.75 m, step is used 80 cm.

Rafters for single-pitched and double-pitched roofs

What is the distance of the rafters for a pitched roof? shed roof does not require a complex truss structure. The rafters are laid from wall to wall, most often without the use of a Mauerlat, directly on the crown.

No extra ribs stiffness sets the maximum slope angle - 30 degrees and allowable span length - less than 6 m(for wooden rafters). The optimal angle 15 - 20 degrees.

Such roofs usually not subject to wind loads, but require protection from precipitation. In regions where wind pressure is comparable to snow load, correct installation shed roof "downwind" can lead to self-cleaning of the roof.

gable roof is a system of parallel triangles interconnected by a Mauerlat and a ridge. There are many elements for firmly fastening the sides of the triangle to each other and transferring loads from the rafter legs to the walls - racks, ties, jibs, support beams, and so on.

The step between the rafters of a gable roof is made taking into account the size of the heat insulator that is laid between them. Approximate step between rafter legs 1-1.2 meters

Rigid Triangle Strength increases as its shape approaches isosceles, therefore, with an increase in the slope angle up to 60 degrees you can expand the step between the rafters.

However, this will also lead to an increase in material consumption and to a multiple increase in the windage of the roof. The optimal slope angle for snowy regions is 45 degrees, for windy - 20 degrees.

Distance between rafters roofs attic type determines how much of the load falls on each element. When designing hip roofing step rafters should be between 60 cm and 1 m.

The correct fastening of the rafters is no less important than the correct calculation of the structure. Front self-assembly the roof is worth taking a lesson from an experienced carpenter and reading educational literature.
When choosing a rafter pitch, do not forget about thermal insulation. All types of insulation can shrink a little, so you can buy them by approximate size. The most commonly produced sizes are 60, 80, 100, 120 cm.
For roofs with a slope of 45 degrees or more, the weight of a person on the roof can be ignored. This removes 175 kilograms of design load per square meter and allows you to put rafters on average 20% less often.
Snow and wind load in Russian regions can be found by regulatory documents - maps in the application F To .
There are many online roof calculators on the web., capable of, if not correctly calculating all the nuances, then at least advise on the selection of the correct section for the rafters.

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, then roofing deformed, 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, the main task of any project is to calculate 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 identify given value you need to matter total load, roof parameters and rafter wood data.

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 the regions of the country where a large number of precipitation in the form of snow, 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. The designed truss systems must necessarily 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. This is due to the dimensions of the 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 with a slate roof is 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;
Usually, wooden system under 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

Recently, the shed roof is gaining 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). by the most optimal slope 15-20 degrees is considered. 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 the snow mass from the roof in a natural way.

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 the building is one of the most important elements the entire building. If you start saving on a roofing pie, then soon you will face costly repairs that will affect not only this area, 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.