How to calculate the distance between the rafters. Interrail distance: calculation technology. Features when choosing the distance between rafters for metal and ceramic tiles

The distance between the rafters is one of the key parameters affecting the strength of the structure. Competent calculation of the step of installing the rafters allows you to build a roof that is resistant to high operational loads.

Roof loads and calculation of the rafter system

The development of a project of a gable or gable roof begins with the choice of the type of rafter system, the angle of inclination of the slopes (roof height) and materials for the construction of the structure. The calculation of the distance between the rafter legs is carried out taking into account the loads that the roof will experience during operation. Permanent loads include:

the weight of the materials from which the rafter system is made;
roofing weight;
the weight of the materials of the roofing cake (waterproofing, vapor barrier, insulation);
weight of finishing elements of a residential attic or attic.

In addition to permanent loads, the roof also experiences temporary loads, which include:

snow cover weight;

the weight of a person during the maintenance and repair of the roof.

The step means the distance between the rafters of one slope. When calculating a shed, gable or complex roof, they usually adhere to the following scheme:

the length of the future roof slope is measured;
the resulting value is divided by the optimal numerical value of the rafter pitch;
one is added to the resulting value, the result is rounded;
the length of the roof slope is divided by the rounded result.

The final result will allow you to determine through what distance the rafter legs should be placed. Determination of the step cannot be extremely accurate, since it is required to take into account a number of additional factors, including the width of the insulation, the features of installing the battens for various types of roofing material. If a roof with a chimney is being designed, the pitch can be adjusted taking into account its location so that you do not have to remove part of the rafter in the future and install a supporting structure, such as a special rafter system.

The distance between the rafters under the slate

Slate is a traditional roofing material. Its advantages include such characteristics as resistance to external influences (excluding mechanical) and low cost. The slate allows you to create a roof covering, the repair of which can be reduced to the replacement of individual elements. The slate is heavy and requires the installation of a sufficiently powerful rafter system. The calculation of the distance at which it is necessary to put the rafters under the slate is carried out taking into account the section of the beam for the manufacture of rafter legs.

The optimal solution is to install the system under the slate, in which the gap between the rafters should be at least 800 mm. In order for the slate structure to withstand not only the weight of the material, but also increased external loads, the lathing is made of a bar or board with a cross section of at least 30 mm. When calculating the rafter system for slate, it should be read that this material has rather large restrictions on the choice of the angle of inclination of the slopes.

Rafters for metal tiles

Metal tiles are actively used as a practical and aesthetic roofing material when arranging a pitched, gable, hip or complex roof. The frame for metal tiles is built according to standard principles. To calculate at what distance it is better to put the rafters, it is necessary to take into account the loads and the angle of inclination of the roof. The metal tile is characterized by a relatively low weight, due to which it can serve as a replacement for old roofing from slate or ceramic tiles. In this case, the rafters do not need to be strengthened or changed the step of their installation.

The standard pitch of rafters for metal tiles is 600-900 mm. The cross-section of the elements can be 50-150 mm - this is enough to create a reliable frame for metal tiles. But if it is planned to use insulation, the layer of which in areas with low winter temperatures should be 200 mm, it is recommended to use a 200x50 bar for rafters under the metal tile, so as not to mount an additional system that holds the insulation. It is better to adjust the gap between the rafters under the metal tile to the width of the sheet or roll heat insulator.

Decking: rafters and lathing

Decking refers to lightweight and easy-to-use roofing materials. Galvanized or covered with a decorative protective layer corrugated board can be used both for the installation of a pitched roof of a utility room or garage, and for a gable roof of a residential building. How to calculate the distance required to install the rafters under the corrugated board?

To ensure the required rigidity of the structure, it is enough to install the rafters under the corrugated board with a step of 600-900 mm. In this case, it is necessary to pay attention to the angle of inclination of the roof. The calculation shows that at high external loads, it is better to lay the corrugated board on the system with a minimum step. But if the distance between the rafters under the corrugated board is close to the maximum, and the slope angle of the roof is small, then the structure is enhanced by using more frequent lathing. In this case, the pitch of the lathing for the corrugated board should be about 50 mm, the width of the elements should be at least 100 mm.

Rafter system for a soft roof

Soft roofing includes bitumen and bitumen-polymer roll materials, roofing membranes, as well as soft tiles. The soft roof is characterized by a relatively low weight and the absence of the need to install a massive truss structure.

The minimum distance between the rafter legs is 600 mm, the maximum is 1500 mm. When installing a support under a soft roof, it is important to take into account the angle of inclination of the slopes: the smaller the angle, the smaller the distance between the supports for a solid lathing should be. The choice of step is also influenced by the thickness of the material for the lathing - the thicker the plywood or OSB sheet, the larger the step of installing the rafter legs can be.

Ondulin: calculation of rafters

Ondulin (bituminous slate) is laid on a flat solid crate made of sheet material. This allows the roofing to successfully resist wind and snow loads. The lathing for ondulin rests on the rafters, which should be located in increments of 600 - 1000 mm, depending on the angle of inclination of the gable or single-pitched roof.

Rafters for ondulin are made of a bar with a section of 200 × 50 mm. When choosing at what distance to put the rafter legs for the structure under the ondulin, it is recommended to take into account the width of the insulation material in order to simplify its installation. This calculation allows you to reduce the financial costs of arranging the roof.

Sandwich panel roof

Sandwich roofing is most often erected on houses made of vulture panels or hangar-type buildings. A feature of the sandwich is its bending rigidity, which makes it possible to dispense with the installation of traditional rafters. Small spans from the ridge of a gable roof to the upper part of the wall (or the distance between the supporting structures of a pitched roof) allow sandwich installation without additional supports.

If the span is longer than 4 meters, additional purlins must be installed. To mount a sandwich roof on a residential building, a traditional rafter system is often installed, but in this case, the rafters can be positioned with a large pitch - they serve as a support for the girders. The distance between the rafter legs is selected based on the length of the available material for the purlins and the length of the load-bearing walls. The technical parameters of the sandwich allow the roof to withstand high operational loads.

Polycarbonate: erecting the support structure

Recently, polycarbonate has been actively used as a roofing material. First of all, polycarbonate is in demand in the construction of gazebos, sheds, winter gardens. The lathing and truss system for polycarbonate can be made of wood or metal.

In building a house, it is important that the roof frame and its truss structure are reliable. To do this, you need to know the optimal dimensions of the gap between the rafters. How to correctly carry out calculations for the rafter system of a gable roof, taking into account various roofing materials, our experts will tell in this article.

How to calculate the distance between the rafters (for a gable roof)

Distance for various roofing materials

Experts advise: when determining the step between the rafter supports, take into account the roofing material from which the gable roof will be created. Let's consider the most common roofing options suitable for private residential buildings.

Decking - for this roofing material, the distance we need to the digital indicator is from 60 to 90 centimeters (with an increase in the step of at least one meter, you will have to install additional transverse boards with a large section - 5 × 10 cm). At the same time, under the corrugated board, it will be necessary to install the crate, which will ensure the possibility of fastening the obligatory vertical components - the chimney, the ventilation system.
Ceramic tiles - a roof made of such a material has a rather heavy weight, therefore, the load on the rafter system will be higher than when covering the roof with corrugated board. Accordingly, the distance that we calculate will be different: from 80 centimeters to 1 meter 30 centimeters. But in this option, the steepness of the roof slope is also taken into account (if the angle of inclination is 15 degrees, then the gap will be minimal - 80 cm, at 75 degrees - 130 cm).
Metal tile - this roofing material is lighter than the previous one and is sold immediately in sheet form, therefore, the thickness of the components of the rafter system decreases, and, therefore, the distance between the elements in it decreases. For rafter material with a cross section of 15 × 5 centimeters, the gap should be selected from 60 centimeters to 95 centimeters. This distance will allow for high-quality insulation of the attic (for this it is necessary to place the insulation material directly between the rafters). The peculiarity of the installation of the truss structure under the metal tile is that the supports are installed on top of the ridge girder (usually they are installed on the ridge beam from the side). But in this case, do not forget about the ventilation holes near the upper roof.
Ondulin - this material is called "euro slate", and it is perfect for the roof of private residential buildings. For the rafter structure for ondulin, rafters made of boards of 5 × 20 centimeters are used, which provides a certain margin of safety (this also takes into account the rafter runs). The distance between such rafter boards is standard - from 60 to 90 centimeters, and the wooden beam for the lathing should be 4 × 5 cm in cross section, with a center step of 60 cm.
Slate is one of the most common roofing materials in our country; under it, rafters should be selected with a cross section of 5 × 10/5 × 150 centimeters. The distance between them will be slightly in a smaller range - 60-80 cm.The lathing made of wooden beams has its own gap between the elements, which directly depends on the slope angle of the roof slope: with a small slope - from 45 cm, with a larger one - from 60 cm.

Thus, the general digital indicators for determining the distance between the rafters (depending on the roofing material) will fluctuate within the following limits: the minimum is 60 cm, and the maximum is 130 cm.If you yourself cannot decide on the choice of such a digital indicator, then you should contact to qualified specialists for help.

Roof loads and calculation of the rafter system

the weight of the materials from which the rafter system is made;
roofing weight;
the weight of the materials of the roofing cake (waterproofing, vapor barrier, insulation);
weight of finishing elements of a residential attic or attic.

In addition to permanent loads, the roof also experiences temporary loads, which include:

snow cover weight;

the weight of a person during the maintenance and repair of the roof.

The step means the distance between the rafters of one slope. When calculating a shed, gable or complex roof, they usually adhere to the following scheme:

the length of the future roof slope is measured;
the resulting value is divided by the optimal numerical value of the rafter pitch;
one is added to the resulting value, the result is rounded;
the length of the roof slope is divided by the rounded result.

The distance between the rafters under the slate

Rafters for metal tiles

Decking: rafters and lathing

Rafter system for a soft roof

Ondulin: calculation of rafters

Sandwich panel roof

Polycarbonate: erecting the support structure

Polycarbonate varies in weight depending on the thickness of the sheet. It is recommended to carry out lathing for polycarbonate with a step of 600-800 mm. The lathing (wood or metal) is mounted on rafters, which can be straight or arched. Typically, the gap between the rafters for polycarbonate is from 1500 to 2300 mm. In order to correctly calculate at what distance it is better to bleed the rafters, it is necessary to take into account the glazing area, dimensions and thickness of the sheets, take into account that polycarbonate is fastened with gaps for thermal expansion.

The distance between the rafters of a gable and a pitched roof

Find out what distance between the rafters you need to make for a gable and a pitched roof. The maximum distance between the rafters for metal tiles, ondulin and soft roofing.

Distance between rafters: principles and examples of calculating the pitch of the rafter system

The task of correctly calculating the distance between the rafters is a very responsible one. Not only the reliability and durability of the roof will depend on how seriously you start solving it, but also all subsequent work on it: laying insulation, installing roofing, installing additional elements. If you juggle the step of the rafters under the sheets of the roof, as many do, then it is not a fact that insulation will then enter between the rafters. If you focus only on insulation, the very first winter with its abundant Russian snow will crush the rafter system. That is why the whole point is to choose the optimal rafter pitch for all slopes, and we will teach you this skill now.

What determines the pitch of the rafters?

So, the distance between the rafters is determined by such important factors:

Roof shape (gable, single-pitched or multi-pitched).
Roof inclination angle.
Parameters of the timber used for the manufacture of rafters (width, thickness).
The structure of the rafter system (layered, hanging or sliding).
The aggregate of all loads on the roof (coating weight, weather conditions, etc.).
Sheathing material (20x100 or 50x50) and its parameters (solid, with gaps of 10 cm, 20 cm or solid plywood)

And each of these parameters must be taken into account, which is exactly what this article is about.

Decorative rafters: 0% load

First of all, decide on the most important point: the type of roof and its purpose. The fact is that the roof of a residential building in winter withstands a large cap of snow, a constant wind at a height and is often insulated from the inside, but completely different requirements are imposed on the rafter system of a small gazebo hidden under the crowns of trees.

For example, if you are building a pergola in its classical sense, then it does not matter at all what distance between the rafters it will have - this is already a purely aesthetic factor:

In the above illustration, it can be seen that even in such a building there is its own rafter pitch. Indeed, here it provides both the aesthetic factor and the rigidity of the structure itself. But they choose a step in an arbitrary way.

Functional rafters: detailed calculation

We come to the main question: what should be the distance between the roof rafters of a residential building? Here, be patient and carefully study all the nuances.

Point 1. The length of the wall and the choice of the pitch of the rafters

First of all, the step of installing rafters on the roof of a residential building is usually chosen structurally to the size of the building, although taking into account many other factors.

For example, the easiest way is to install rafters in 1 meter increments, so 7 rafters are standard for a 6 meter long wall. At the same time, you can save money by placing them with a distance of 1 and 2 meters, and you get exactly 5 rafters. It can also be placed with a distance of 2 and 3 meters, but reinforced with a crate. But it is highly undesirable to take a step of the rafters more than 2 meters.

Clause 2. Influence of snow and wind loads on the shape of the roof

So, we settled on the fact that the average distance between the rafters of a conventional roof is 1 meter. But, if there is a significant snow or wind load in the area, or the roof is more or less sloping or just heavy (for example, covered with clay tiles), then this distance must be reduced to 60-80 cm. But on a roof with a slope of more than 45 degrees, it can be even increase to a distance of 1.2m-1.4m.

Why is this so important? Let's figure it out. The fact is that the air flow collides on its way with the wall under the roof of the building, and there are turbulences, after which the wind hits the eaves overhang of the roof. It turns out that the wind flow, as it were, bends around the slope of the roof, but at the same time trying to raise it. And at this moment, forces arise in the roof that are ready to rip it off or overturn it - these are two windward sides and one lifting side.

There is another force that arises from wind pressure and acts perpendicular to the slope, trying to push the roof slope inward. And the greater the angle of inclination of the roof slope, the more important are the safe wind forces and the less tangents. And the larger the angle of the slope, the less often you need to put the rafters.

To understand whether to make you a high roof or a shallow one, this map of the average wind load will help:

The second point: in the Russian region, an atmospheric phenomenon such as snow constantly affects a standard roof of a house. And here, too, you need to consider that the snow bag usually accumulates more on one side of the roof than on the other.

That is why, in places where such a bag is possible, you need to insert paired rafter legs or make a solid crate. The easiest way to identify such places is by the wind rose: single rafters are placed on the windward side, and paired on the leeward side.

If you are building a house for the first time, then you will not find your own worldview, but determine the average snow load for your area according to official data:

Clause 3. Issue of insulation and standard width of mats

If you are going to insulate the roof, then it is advisable to place the rafter pitch under the standard dimensions of the insulation plates, which are 60, 80 cm and 120 cm.

Modern insulation today is sold in a standard width, usually at the same standard rafter pitch. If you then take them and adjust to the already existing parameters, then there will be a lot of waste, cracks, cold bridges and other problems.

Item 4. The quality and strength of the lumber used

It is also of great importance what kind of material you use for the construction of the rafter system. So, for each type of wood, there is its own regulatory documentation that relates to its bearing capacity:

Because for the manufacture of roof truss systems in Russia, pine and spruce are most often used, their bending strength and features of use have long been spelled out. If you use wood of other species, then it will be possible to display a correction factor.

In addition, if there are sections, cuts or bolt holes on the rafters, in this place you need to calculate the bearing capacity of the bar with a factor of 0.80.

Item 5. Distance between tie rods and floor beams

Another point: if the roof is built with trusses connected to each other, and their lower chord is used simultaneously as floor beams, then the distance between the trusses must be made within 60-75 cm in order to take into account the design of the future floor.

Item 6. Loads on roof trusses

So, here are the main loads that act on the roof truss system:

Static, which includes the weight of the rafter system itself, the weight of the roof, snow lying on the roof and additional elements.
Dynamic, which includes wind force, unexpected damage to the roof, the weight of a person and equipment for repair, and similar factors.

And all these factors are capable of simultaneously affecting the roof at a certain moment, and therefore there is such a thing as critical value. This is exactly the value of the loads at which the roof does not withstand and deforms.

Therefore, if a building is being built with significant spans, then steel trusses are necessarily used. The fact is that there is no stress in such rods, and the entire load falls on the nodes - here they are affected by compressive and tensile forces. And the distance between such trusses is calculated depending on the type of roof and the structure of the roof itself.

Usually, a unified truss is placed with a span that is a multiple of six, and therefore a distance is made between the nodes of the truss in a multiple of one and a half meters.

Item 7. Weight of the rafter system and roofing cake

Do not forget that the main purpose of the rafters is to hold the entire roof on itself, and its weight is critical in this case:

Item 8. Convenience of installation of roofing

The distance between the rafters is also influenced by such a factor as the selected roofing. The higher the slope of the roof, the more roofing materials will be used. And the heavier they are, the more often you will have to put rafters under them. But what about the solid crate? The fact of the matter is that it also has its own weight:

Each type of roof has its own optimal rafter pitch. After all, many standard sheets along the edges need to be fastened directly to the rafter or crate, and it is important that they match. Otherwise, the work on roofing will easily turn into a living hell at a height, believe me.

That is why, even before starting installation, it is imperative to make a layout, check everything several times. And know some important subtleties for each type of coating.

Determination of the totality of loads on the roof as a whole and the rafter separately

So, we have determined that, in addition to other design factors, a whole set of loads simultaneously acts on the roof rafter system: the weight of the rafter system, a cap made of snow, wind pressure. After you add all the loads together, be sure to multiply them by a factor of 1.1. So you all rely on unexpected favorable conditions, that is, lay an additional 10% percent strength.

And now you just have to divide the total load by the planned number of rafters and see if each of them will cope with its task. If it seems that the structure will be frail - feel free to add 1-2 rafters to the total, and you will be calm about your home.

You need to do the calculation for destruction, i.e. full load on the roof. All these loads are determined by the technical characteristics of materials and SNiPs.

The standard roof structure is rafters, lattice girders, and each of these elements is triggered only by the load that presses on it, and not on the overall roof as a whole. Those. each individual rafter has its own load, total, but divided by the number of rafter legs, and by changing the pitch of their location, you change the area of collection of the load on the rafters - by reducing it, or increasing it. And, if it is inconvenient for you to change the pitch of the rafters, then work with the parameters of the section of the rafter legs, and the total load-bearing capacity of the roof will increase significantly:

With this calculation, try to ensure that the longest rafter in your project is no more than six and a half meters, otherwise, splicate along the length. Let us explain in more detail now. So, on roofs with a slope of up to 30 degrees rafters are the so-called "bendable elements". Those. they work precisely for bending, and there are certain requirements for them. And the possibility of deflection of the rafters is calculated according to a special formula, and if the result exceeds the norm, then the rafters are increased in height and a new calculation is made again.

But on a roof with a warehouse slope of more than 30 degrees, which rafters are already considered "bend-compressed" elements. That is, they are affected not only by a uniformly distributed load, which causes the bending of the rafters, but also by the forces that are already acting along the axis of the rafter. In simple terms, here the rafters not only sag slightly under the weight of the roof, but also squeeze from the ridge to the Mauerlat. In addition, the crossbar, which usually holds the two rafter legs, must also be checked for tension.

As you can see, even a person far from construction can cope with such calculations. The main thing is to take everything into account, to be attentive and ready to spend a little more time on design, so that later all the work would go like clockwork!

Distance between rafters: what step should be between the rafters

Detailed instructions on how to correctly calculate the distance between the rafters of roofs of different structures, taking into account the sum of the loads and the material used.

Before installing the rafter system, the question arises, with what step to put the floor beams. Correctly calculating the distance between the rafters means subsequently preventing deformation or even destruction of the roof frame. After reading the article to the end, readers will find out what should be the distance between the rafters for a different type of roof and how to correctly calculate.

Even at the design stage of a wooden house, all load calculations must be made. This also applies to the rafter system. This is especially important in wooden housing construction, since the top link is often used instead of the Mauerlat. It is difficult to correct errors in such a design later. There is a technique for correctly calculating the distance between the beams.

The span of the roof frame for the construction of a house from a bar usually exceeds 1 m, and the smallest allowable value is 60 cm, such indicators are indicated in GOSTs (see figure). You can correctly calculate the length of the rafters, their step, as follows:

Using a tape measure, the length of the roof slope is measured, the result is divided by the step size of the roof frame. For example, if the distance between the rafters is 1 m, then you need to divide by 1, if 70 cm, then by 0.7. The resulting figure is added to 1 and rounded to the nearest higher number. This allows you to determine the number of beams for one roof slope.

You need to divide the length of the future slope by the result obtained. The result is the distance between each rafter.

For example, consider a roof, the slope of which is 25.5 m and a step of 0.6 m. You need to calculate the following indicators: 25.5: 0.6 = 42.5, to 42.5 + 1 = 43.5. We round this figure to the nearest larger integer, we get 44. This is the number of rafter beams per 1 slope of the future roof.

Now we calculate the span between the rafters: 25.5: 44 = 0.58 m.It turns out that you need to put the legs of the frame every 58 cm.This way you can easily calculate the step of any roof frame, single-pitched or complex, without taking into account the roof. But professionals recommend their calculations for a certain type of roof.

Rafter leg step depending on material

Since each forging material has its own characteristics and characteristics. Among the most common are:

Decking. It has a different thickness and shape of the tropeziform bend. Costs from 120 rubles.
Ceramic tiles. Expensive material from 670 rubles. Has 12 color options.
Metal tiles. This is a cheaper material in contrast to ceramic and costs from 320 rubles.
Ondulin. The soft roof insulates the house from rain, hail, etc. Costs from 340 rubles.
Slate. The most economical option from 90 rubles.

The step size for the most common types of coverage is discussed below.

Step of rafter beams for corrugated board

The distance between the roof beams depends on the size of the sheet that the corrugated board has. The pitch of the beams of the roof frame under the corrugated board is taken as standard not less than 60 cm and not more than 90 cm.

If this distance is greater, then boards with a large section are attached between the rafter beams. The cross-section of the rafter legs for the corrugated board is chosen 50x100 or 150 mm.

The most important thing to consider when going to fasten the corrugated board is the crate. They make it from a board with a section of 30x100mm, you need to mount it with a span of 50 cm. It depends on the brand and thickness of the corrugated board and the slope of the roof.

So a 15 ° roof, C 10 brand corrugated board is mounted on a solid crate, C 21 corrugated board is mounted on a crate with a span of 30 cm. The largest C 44 corrugated board is mounted on a crate with a pitch of 50 cm, up to 1 m. chimney passage, ventilation hood, etc.

Step of rafter beams for ceramic tiles

The specificity of the installation of the truss system for laying ceramic tiles is associated with the weight of this roof. They make ceramic tiles from clay, and this roof has a weight 9-10 times more than that of a metal tile. Calculation of the load on the rafter system for ceramic tiles is 40-60 kg / m 2.

Beams for the roof truss system are made for ceramic tiles only from dried material. The section is suitable for 50x150 or 60x180 mm. The standard distance between the rafter legs when roofing tiles is 80-120 cm. The span depends on what slope the roof has. At an angle of 15 °, the span between the rafters is 80 cm, at 750 through 1 m 30 cm.

When calculating the pitch, you need to take into account the length of the beam. Taking the maximum length, the distance between the rafters is minimal. And, on the contrary, with the minimum length of the rafters, the step is maximum.

When laying ceramic tiles, it is important to take into account that you will need to move along the roof. The safest step of the rafter legs for such movement is 80 cm.

It is important when laying ceramic tiles to calculate the span of the sheathing. This distance is directly related to the size of the roofing material. A standard shingle sheet is 40 cm long. It is laid with an overlap of 50 to 90 mm. Calculating the step of the battens, the size of the overlap is subtracted from the length of the tiles. The result is a step of 305-345 mm.

For a pitched roof for the construction of a house from a profiled beam, it is not difficult to make a calculation. If the roof is of a complex multi-pitched shape, then each distance between the rafters is calculated separately for the sheathing step. By fixing the cord on the opposite side of the roof slope, you can easily mark the rows.

Features of the roof frame for metal tiles

Metal tiles are used more often than ceramic or corrugated board. Externally, the roof resembles ceramic tiles, but unlike it, it is easier to install and lighter.

The metal tile weighs from 35 kg / m 2 of the roof. This makes it possible to lighten the structure of the rafters and use beams with a smaller section. The step between the rafter legs of the roof frame increases and is equal to 60 to 90 cm. The beam is used with a section of 50x150 mm.

To create a ventilated space in the beams under the roof, holes with a diameter of 12-13 mm are drilled.

The design of the roof frame for metal tiles is not much different from corrugated board or ceramic tiles. But there is a small feature: the support from above is attached to the ridge girder from above, and not from the side as in other cases. So a ventilated gap will appear under the metal tiles, which will exclude the accumulation of condensation.

Features of rafter legs for ondulin

Ondulin is a soft roofing used for the construction of a house made of laminated veneer lumber or other material. Ondulin is produced in the form of sheets; it looks like painted slate, but lightweight. This material is great for both low-rise and large wooden houses.

The rafter beams for ondulin are placed with a distance of at least 60 cm, a maximum of 90 cm. For the rafter system, a coniferous timber with a section of 50x150 or 50x200 mm is used. A smaller section will not provide sufficient strength to the rafter girders.

The lathing on the rafters is made of a material with a cross section of 40x50 mm with a step of 60 cm.This is quite enough for fastening ondulin sheets with an overlap of 30 cm. Ondulin is fastened with special nails that are sold in the kit.

Features of the rafter system for slate

Slate is rarely used to cover the roofs of modern houses. But in dacha construction and households. buildings, this material is irreplaceable. It is low cost and easy to install.

Slate rafters

Rafter legs for slate are used with a section of 50x100 or 50x150 mm. The fastening step between the rafters is not less than 60 cm and not more than 80 cm.

The slate lathing is made of 50x50 mm bars or a wide board of 30x100 mm. The lathing is laid from the steps, depending on the roof slope. For a steep pitched roof, it is 45 cm. Consumption is 4 bars per 1 sheet of slate. For a flat shed or gable roof 63-65 cm, so the consumption is reduced to 4 bars per sheet.

The step of the rafter system under the slate differs by the roof structure. For households. buildings are often mounted shed.

Dimensional feature between the rafter beams at a pitched and a gable roof

Whether a safety margin is needed during installation depends on what shape the roof is. And the distance between the rafter beams directly depends on this.

Single slope rafter system

A pitched roof is more durable and easier to assemble. The thickness of the rafters is selected depending on the type of wood, its strength and the specificity that this or that structure has. The step between them can be 60-140 cm. The distance also takes into account whether the structure will be insulated. If so, then the step should correspond to the width of the insulation.

The thickness of the rafter beams must be calculated depending on the roof slope. For a slight slope of 15-20º, you can use a material with a section of 50x100 mm. For a steep slope of 45º, a more durable section of 50x150 mm is needed.

Gable rafter system

If the calculation of the step of the legs of the frame of a pitched or other type of roof is not correct, then the roof can be taken away, and the beams will sag and bend from the weight of the structure. In this case, simple repairs will not be enough, you will have to redo the entire structure. Therefore, it is so important to correctly calculate the distance between the legs of the rafters, depending on the roofing material used: corrugated board, ceramic or metal tiles, ondulin or slate, etc.

Roof loads and calculation of the rafter system

the weight of the materials from which the rafter system is made;
roofing weight;
the weight of the materials of the roofing cake (waterproofing, vapor barrier, insulation);
weight of finishing elements of a residential attic or attic.

In addition to permanent loads, the roof also experiences temporary loads, which include:

snow cover weight;

the weight of a person during the maintenance and repair of the roof.

The step means the distance between the rafters of one slope. When calculating a shed, gable or complex roof, they usually adhere to the following scheme:

the length of the future roof slope is measured;
the resulting value is divided by the optimal numerical value of the rafter pitch;
one is added to the resulting value, the result is rounded;
the length of the roof slope is divided by the rounded result.

The distance between the rafters under the slate

Rafters for metal tiles

Decking: rafters and lathing

Rafter system for a soft roof

Ondulin: calculation of rafters

Sandwich panel roof

Polycarbonate: erecting the support structure

The distance between the rafters of a gable and a pitched roof

Find out what distance between the rafters you need to make for a gable and a pitched roof. The maximum distance between the rafters for metal tiles, ondulin and soft roofing.

What is the distance between the rafters of a gable roof

Roofing is the final stage of any construction. This structural element is a load-bearing structure that takes all the loads, and then evenly distributes them over the surface of the load-bearing walls of the house.

Gable roof

A gable roof is rightfully considered the most common option for arranging suburban housing. And there is a completely logical explanation for this. It's no secret that the simpler the structure, the simpler it is to build and the higher its reliability and performance characteristics.

The gable roof has a triangular shape and consists of two pitched planes, connected at the highest point by a ridge girder, and the same number and shape of gables.

Basically, the construction of a gable roof is not considered such a difficult operation. But, despite all the simplicity, it requires the most responsible and thoughtful approach.

Structurally, the gable roof has two slopes located in relation to the wall elements of the house at a certain angle, which ensures natural removal of precipitation from its surface. Also, gable roof structures can be of the attic or mansard type.

As a rule, gable roofs are installed on one-story, architecturally simple structures. A huge plus is that the rafters in this case will not be particularly difficult to install.

The angle of inclination of the roof slopes of gable roofs

The angle of inclination of a gable roof cannot be less than 5 degrees, and in some cases it can even reach 90 degrees. Only at such an angle of inclination of the roof slopes, the rafters will be able to adequately cope with the function assigned to them.

The choice of the angle of inclination of the slopes for a gable roof is influenced by a huge number of factors, such as climatic features, the type of roofing material chosen and the architectural style of the building.

For example, sloping roofs are ideal for areas where strong hurricane winds are constantly blowing, but structures with steep slopes are a great option for areas with impressive rainfall.

Also, the angle of inclination of the roof affects its cost, this is due to the fact that much more roofing material will go to a roof with a small angle of roof slopes than with a large one.

However, this is not the only important parameter in the construction of a gable roof. Equally important when forming a gable roof is the correct installation and fastening of the rafter system, as well as the size of the step between its elements.

Also, the quality of the structure is affected by the fastening of the rafters to the Mauerlat and the ridge girder. It is possible to form a particularly reliable fastening with the help of a cut and additional fastening of the connections with bolts.

The distance between the rafter legs (otherwise, the step of the rafters) is considered one of the most important parameters when installing a roof, which affects its strength characteristics.

A correctly calculated pitch between the rafters of a gable roof allows you to form a roof that is resistant to the high loads to which it will be subjected during operation.

Let's take a closer look at what the distance between the legs of the rafters should be.

Step rafters for a gable roof

The distance between the rafter legs of the gable roof is calculated during the design process. It is quite problematic to correct any mistakes made at this stage, and therefore if you are not confident in your own abilities, then it is better to entrust its implementation to professional architects.

Reliable rafters are the foundation of any house roof.

The rafter step is calculated taking into account the loads to which the structure will be subjected during operation, and the angle of inclination of the roof slopes.

With a competent calculation, the presence or absence of an insulating layer, the cross-section of the structural elements of the rafter system, the type of lathing and roofing must be taken into account. It is necessary to correctly calculate the loads, as this will help not to make a mistake when choosing the cross-section of the rafter.

A rafter step is the distance between two adjacent rafter trusses.

Step-by-step instructions for calculating the pitch of the rafters for a gable roof:

We calculate the estimated length of the roof slopes.
Divide the resulting number by the optimal step size.
Add one to the resulting number and round the result.
Divide the length of the slopes by the rounded result.

As a result of these simple calculations, you will get the distance at which the rafters should be installed.

The step between the rafters cannot be calculated accurately, since in order to obtain more accurate data, it is necessary to take into account a huge number of parameters, starting from the width of the insulation layer, the type of roofing material and even the distance between the elements of the gable roof sheathing. Rafters, installed correctly, will serve you faithfully for more than a dozen years.

Step of rafters under asbestos-cement slate

An important parameter of asbestos-cement slate is its significant weight, due to which it requires the installation of powerful rafters that can withstand heavy loads. The distance between the rafters is selected based on the section of the timber used to make the rafters.

It is equally important that the fastening of the rafters of the gable roof is performed correctly, as this will provide it with a high degree of reliability and a long service life.

The optimal pitch between the rafters when using asbestos-cement slate should not be less than 800 mm. Thanks to this, the rafters will be able to easily cope with the task assigned to them.

Rafters for metal tiles

We will not talk about all the advantages and disadvantages of this material, a lot has been said about this. Let's take a better look at what should be the step between the structural elements of the structure. Rafters for metal shingles are installed in accordance with existing norms and requirements.

Due to its low weight, this coating can be used to cover roofs on which ceramic tiles or asbestos-cement slates were previously laid.

The size between the rafters in this case ranges from 600 to 900 mm, and the section of lumber is 50 by 150 mm. Such a step between the rafters will create the most reliable supporting frame for the roof.

However, in areas characterized by snowy winters, it is preferable to equip the distance between the rafters of 200 mm, and to use a bar with a section of 50 by 200 mm for the manufacture of structural elements.

In order not to mount a special system to maintain the insulation, the distance between the rafters can be adjusted to the width of the thermal insulation material.

Rafters for ondulin

Ondulin or shingles should be laid on a solid, perfectly flat crate, and it is better if it is made of any sheet material, which will allow the roof to withstand all loads.

The lathing is attached to the rafter legs, located in increments of 600 to 1000 mm, depending on the angle of inclination of the gable roof slopes.

Correctly selected distance between the elements of the rafter system guarantees the entire supporting frame a high degree of strength and durability of the entire structure.

What is the distance between the rafters of a gable roof, YouSpec Construction Encyclopedia

Correctly selected distance between the elements of the rafter system guarantees the entire supporting frame a high degree of strength and durability of the entire

Distance between rafters: correct calculation

The reliability of the roof and its service life mainly depend on how correctly the calculations are made.

One of the most important parameters of the rafter system is how far from each other the rafters are located.

After all, the distribution of the load on the frame depends precisely on this desired parameter.

If the calculation is not correct, deformation may occur and the roof will collapse.

Therefore, it is extremely important to accurately calculate the distance between the rafter legs when drawing up a roof project.

The main provisions of the calculation

The step of the rafters is the distance from one rafter leg to the other.

When building roofs of private houses, this value is equal to 1 meter.

But this figure is approximate.

To get the exact size of the interval, it is necessary to calculate the bearing capacity of the rafter system of the selected type.

To perform a correct calculation, the following scheme should be used:

first it is necessary to determine what is the length of the roof slope;
now the resulting figure should be divided by the value of the approximately selected rafter step. If you pre-selected its value of 1 meter, then it must be divided by 1.

If 0.8 was chosen, then it should be divided by 0.8, etc.;

after that, add one to the result obtained and round the resulting value up. This action is necessary in order to get the exact number of rafters that need to be installed on one ramp;
the total length of the ramp must be divided by the number of rafter legs obtained in the previous calculation. And we get the exact distance between them.

To understand it better, let's look at an example.

By measuring the length of the roof slope, we got 27.5 meters.

We choose a step of 1 meter to make it easier to count.

Now add the unit 27.5 m +1 = 28.5 m.

Round up to the nearest value and get the number 29.

That is, it is necessary to install 29 rafter legs on one slope of our roof.

Now we divide the length of the roof by their number: 27.5 / 29 = 0.95 m.

So, in our case, the step of the rafter legs should be 0.95 meters.

This is a general calculation.

In which the peculiarity of a particular roofing material is not taken into account.

And he can significantly change this parameter.

When you know what kind of material you will use on the roof, you will have to make some changes to the calculation procedure.

Optimum and minimum value

The step is the unit of account.

After all, it depends, first of all, on the load on the roof frame and the section of the rafter legs.

You can take a thick board for their construction and make the interval between them 120 cm.

At this distance, the lathing may begin to bend.

And how to lay the insulation?

Indeed, most materials have a width of 1 meter.

So they take an approximate step of 1 meter when calculating.

The minimum distance between the rafter legs is 70 cm.

And to obtain the optimal value for each material, it is necessary to perform a calculation.

Determining the pitch for a pitched roof

A pitched roof is the simplest.

Indeed, in the truss of such a roof there are only rafter legs.

There are no braces, struts, braces in its structure.

Such a roof is usually arranged in garages, outbuildings, baths.

As you can see from the table, the rafter pitch depends on their length and section.

Distance between rafters for a gable roof

A gable roof is much more common than a pitched roof.

And to explain such popularity is simple: the design is very simple, but for all its simplicity, the gable roof is distinguished by its reliability.

Its design can be easily adjusted to any climatic conditions and any roofing material.

When calculating the pitch of the rafters of a gable roof, everything is performed according to the general calculation system (see above).

If the slopes are of the same length, then it is enough to perform calculations for one slope.

If the slopes are of different lengths, then the calculation is performed for each slope.

It should be remembered that the limit values for the pitch of the rafter legs are 70 and 120 cm.

What is the step depending on the roofing material

If ondulin is used as a roofing material, then the rafter system is constructed of pine boards with a section of 50 x 200 mm, and the rafters should be located at a distance of at least 60 cm and no more than 90 cm from each other.

A lathing made of a bar with a section of 40 x 50 mm is laid on top.

Metal tile

Metal roofing is most often used in the construction of country houses.

Because this material is much lighter than ceramic or cement tiles.

Although in appearance it is very similar to her.

The low weight of the metal tile makes it possible to use boards of a smaller section when creating a rafter system, and use thinner bars for the lathing.

More about the counter lattice for metal tiles.

About the hip roof with hanging rafters on the link. Also about the construction of hanging rafters.

About the price of Viking metal roofing here. Specifications, photos, reviews.

Reducing the size of the elements of the rafter leg system, in turn, reduces the load on the walls of the building and its foundation.

During the construction of the rafter system under the metal roofing, the rafters are mounted in increments of 60 - 95 cm.

The cross section of the material is 50 x 150 mm.

According to experts, if a heater with a thickness of 150 mm is placed in the gap between the rafters, then the most comfortable living conditions will be created in the attic.

To ensure ventilation of the space where the insulation is laid, during the installation of the rafter system, holes are drilled near the upper roof with a diameter of 12 mm.

The manufacturing technology of the truss system for metal tiles does not differ significantly from the technology for manufacturing the frame for other roofing materials.

Its only difference is the mounting at the top.

The mounting of the upper support is carried out not on the ridge beam from the side, but on the ridge girder.

The presence of a free zone between the rafters allows air to fully circulate under the deck, which helps to prevent condensation from forming.

Ceramic roof tiles

The design of the system for ceramic tiles has its own characteristics.

After all, clay is used for the manufacture of such a roofing material.

And this is a very difficult material.

If we compare metal and ceramic tiles, the latter weighs 10 times more.

Accordingly, the rafter system is significantly different.

For 1 square meter of the roof surface, there is a load of 40 - 60 kg, depending on the manufacturer and brand of the product.

Rafters for such a frame system are made from wood that has undergone a long drying.

Such wood should have a moisture content of no more than 15%.

A bar is used with a cross section of 50 x 150 or 60 x 180 mm.

And the distance between the rafter legs can be 80 - 130 cm.

The exact value can be called if the angle of inclination of the slopes is known.

If the angle of inclination is 15 degrees, then the step of the rafters will be 80 cm.

And if the angle of inclination, for example, is 75 degrees, then the step can be more - 130 cm.

More than 130 cm the interval between the rafters is not made.

Also, when calculating the step of the rafters, their length is taken into account.

The larger the dyne, the smaller the distance between them.

The shorter the rafter legs, the more distance you can make.

If the angle of inclination is 45 degrees, then the roofer can move safely along the roof if the pitch of the rafters is 80 cm.

Corrugated board

When creating a rafter system for corrugated boarding, the minimum distance between the rafter legs is 60 cm.

The maximum size is 90 cm.

If, for some reason, the pitch of the rafters is more than 90 cm, then it becomes necessary to install cross-section boards of a large section.

The rafter legs themselves can have a cross section of 50 x 100 or 50 x 150 mm.

Despite the emergence of a large number of new roofing materials, asbestos-cement slate remains one of the most popular.

If slate is planned to be laid on the roof, then the rafters should have a cross section of 50 x 100 or 50 x 150 mm.

The distance between them is made not less than 60 and not more than 80 cm.

The lathing is made from a bar with a cross section of 50 x 50 mm or a board with a cross section of 25 x 100 mm.

When constructing any building structure, it should be remembered that there are still unforeseen situations.

And, therefore, when calculating the cross-sections of the rafters and the distance between them, it is necessary to provide a margin of safety.

Distance between rafters: single-pitched, gable roof

One of the most important parameters when calculating the rafter system is the distance between the rafters. After all, it depends on him how strong and stable the