Help on Tele2, tariffs, questions

There is no point in arguing about the importance of a roof for any building. It is not for nothing that over the entire history of mankind, more than a dozen different types of roofs have been invented, from simple to quite complex in design and construction. An important element When planning the construction of a roof, there is a step between the rafters - strong bars that are the basis of the structure. This will be discussed in this article.

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

• type of roof;
• slope angle;
• type intended for installation roofing material;
• rafter section sizes.

Before starting the process of erecting the upper structure of the house, you should perform a calculation, determining the optimal distance between the rafters.

Gable roof rafter spacing

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

If the roof slope is insufficient gable roof in snowy areas there is a danger of large snow masses accumulating, which can lead to structural failure. An increase in the angle of the slopes in regions with a predominance of strong winds is also fraught with high loads and the danger of breaking not only the roof, but the entire structure as a whole.

Mansard roof rafter system

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

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

Rafters in a pitched roof

For outbuildings and some private houses use roofs that have one slope. Due to the limitation of the angle of inclination, they are exposed to high pressure. Experts recommend for rafters pitched roof use lumber with an increased cross-section, setting a minimum step from each other.

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

Hip roof rafter system

The hip roof rafter system is considered the most complex in construction. This type is called hipped, since the roof is formed not only by side, but also by additional end slopes, where the rafters are installed not on the ridge, but on the corner strings. This presents special requirements to the organization of the roof frame.

Under hip roof An attic is not often installed. This is due to the small angle of inclination of the rafters and the roof as a whole. If the angle of the slopes to the horizon increases, the distance between the rafters increases; if it decreases, vice versa. An additional aspect of the calculation is the roofing material used.

Dependence of rafter pitch on roofing material

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

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

Corrugated sheet roofing

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

1. High corrosion resistance;
2. As a result, a long (more than 15 years) service life;
3. Easy installation even without the necessary qualifications;
4. Low leaf mass (weight of 1 m2 is 4-5 kg).

Since this roofing material does not place a high load on the rafter system, the distance between the elements is selected as much as possible for a particular angle of inclination. In addition, the profiled sheet does not require high strength characteristics from the roof sheathing. All this together allows us to minimize the overall load on the foundation and walls.

Metal roofing

The second common type of steel roofing materials is metal tiles. This type of corrugated sheet successfully imitates natural clay material, but with less weight (10 or more). A special feature of rafters for metal tiles is their smaller cross-sectional size.

When choosing at what distance to install the rafters, you should first of all be guided by dynamic load. Like corrugated sheets, metal tiles are not demanding in terms of size. rafter legs and is easily mounted on a lathing made of inch board coniferous species. All this does metal roofing low-cost.

Rafter system for ondulin

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

The small thickness of ondulin sheets with slope angles less than 15° requires the construction of a continuous sheathing made of plywood sheets, for example, which will require an appropriate pitch of the rafters. This should be taken into account when making calculations.

Slate roofing

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

High mass comparable to weight clay tiles will not allow using the same rafter system as for metal tiles. Building codes determine the minimum slope angle of a slate roof to be 22 degrees or more. Otherwise, the load from the material itself and rafter system with sheathing exceeds permissible parameters. The pitch of the inclined beams, as well as their cross-section, are selected individually in each specific case.

Polycarbonate on the roof

IN last years Increasingly, artificial polymer material - polycarbonate - has begun to be used on the roofs of verandas and gazebos. Produced in two versions - monolithic and cellular. The first is similar in properties to ordinary quartz glass, but significantly exceeds it in strength. The second has smaller mechanical properties, but with high thermal insulation and light transmittance.

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

Thematic material:

Rafters for soft roofing

An original pattern can be obtained through the use of soft roofing materials, spread with an adhesive layer. Which are installed on continuous sheathing from plywood or OSB. The pitch of the rafters should allow the sheets to be secured, so it is chosen as a multiple of ½ the width. Provided the standard plywood dimensions are 1520x1520 mm, the center distance between the rafters will be equal to: 1520:3 = 506 mm.

Rafter spacing for insulation

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

Scheme for calculating rafter pitch

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

1. determine what distance should be between the rafters for your specific construction conditions. The reference book determines the magnitude of wind and snow loads in the area.
2. The length of the roof is divided by the desired distance, adding one. The result obtained will be equal to the number of rafter legs that are installed on one roof slope. If the value is not a whole number, it is rounded.
3. The length of the roof is divided by the number of rafters calculated above, we get the final pitch in meters.

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

1. 16:0,6+1=27,66;
2. rounding the result, we get 28 rafters per slope;
3. 16:28 = 0.57 meters - the center distance of the rafter legs for these specific conditions.

As you can see, the calculation technology is not complicated, but it is only approximate diagram. Taking into account many of the other parameters mentioned above can make certain adjustments.

The quality and durability of the roof largely depend on correct calculation pitch of the rafters. It affects the installation of insulation, fastening of roofing material and installation of additional parts. Pay attention only to the requirements for the distance under roofing sheets, then problems may arise with the insulation boards. Conversely, adjusting the insulation to fit the dimensions can make the frame too weak, and in winter there is a risk of collapse. How to correctly calculate the distance between roof rafters? We'll talk about this in our article.

As a rule, the pitch between the rafters depends on several factors. But usually the distance ranges between 0.6 and 1.2 meters. These figures are rounded; in practice, the distance may differ by several centimeters downward. For precise definition the following calculations must be performed:

1. Determine the length of the slope by measuring along the eaves of the house. Let's assume that it turns out to be 17.8 meters.
2. Divide the resulting figure by the planned pitch of the rafters. If it was decided that the distance between the beams would be 0.8 meters, then 17.8/0.8 = 22.25.
3. Next, round the result up and add one: 23 + 1 = 24. At this stage, the number of required rafters is determined.
4. Now we calculate the distance between the axes of the beams. To do this, the length of the slope must be divided by the number of rafters: 17.8/24 = 0.74 m.

So, you will determine the actual distance at which the rafters should stand for a roof made of metal tiles or some other material.

Often, when planning a roof frame, specialized calculators are used. They enter basic data and get the finished result. However, you should not completely trust the program, since some conditions can only be taken into account by a person. When calculating, you can understand how the system works, what loads are applied. If necessary, adjustments are made to strengthen or lighten the structure. An independent calculation will help you more accurately determine the required pitch of the rafters of a gable and pitched roof.

Calculation of pitch depending on roofing material

For each coating, its own standards and dimensions for the rafter system are developed. The main factors are the strength of the material, its weight and resistance to external loads. Let's look at the main types of coatings.

Corrugated sheet

The pitch of the rafters under the corrugated sheet can vary from 0.6 to 0.9 m. The final result depends on additional conditions, which we will discuss below. If for some reason the step should be larger, add a cross-section board with a larger cross-section. In this case, the rafters themselves are usually chosen with dimensions of 50x100 or 50x150 mm.

In addition to the rafters, 30x100 mm sheathing is used. The gap between the boards should be about 0.5 meters. It can be more, it all depends on the type of corrugated sheet and the height of the wave. The sheathing boards protruding beyond the boundaries of the cornice should be 1.5 cm thicker than usual. This is done based on the need to attach ventilation, chimney or drainage.

Ceramic tiles

The main difficulty of design rafter frame under ceramic tiles is a large weight of roofing material. It is 10 times heavier than corrugated sheeting and square meter accounts for 40 to 60 kg.

Dry beams with a moisture content of only 15% are used for this coating. Their cross-section should be either 50x150 or 60x180 mm. With such indicators, the maximum permissible distance between the rafters can be 1.3 meters. The minimum permissible step through which rafters can be placed is 0.8 m. The final decision is influenced by the slope of the roof: at 15° the step is 0.8 m, at 75° - 1.3 m.

The length of the rafter leg is also taken into account; the shorter it is, the larger the gap, and vice versa. In addition, if the slope is less than 45°, and movement on the surface is planned, the beams are placed in increments of no more than 0.85 m.

The distance between the sheathing boards is selected so that each intersection of the tiles has its own base. Standard length material is 400 mm, and the amount of overlap during installation ranges between 55 and 90 mm. It turns out that the distance between the central axes of the sheathing can be either 310 or 345 millimeters.

Metal tiles

In recent years, the question has become particularly acute: how to determine the distance between the rafters for metal tiles? It imitates a more expensive one ceramic material, but at the same time has positive properties corrugated sheets Installation of such a coating is simple and does not require large financial costs. All this makes the material attractive for the roofs of private houses.

The mass of metal tiles is less than ceramic tiles, so a simpler frame is required. The cross-section of the beams is reduced to 50x150 mm and the pitch between the sheathing is increased. The pitch of the rafters for metal tiles varies between 0.6 and 0.95 m.

Ondulin

The permissible step for ondulin coating is 0.6-0.9 meters. The standard rafter section is 50x200 millimeters. These dimensions will allow you to withstand the created load. roofing pie on a gable roof.

A lathing made of bars measuring 40x50 millimeters is attached on top of the counter-lattice. The pitch between the central axis is 600 mm.

Additional factors

When calculating the pitch of the rafters, pay attention not only to the type roofing. Many other points are taken into account, data on which can be found in reference books and SNiPs. Here are some of the factors:

1. Snow and wind loads. The more snow falls in winter and the stronger the winds blow, the smaller the distance between the beams should be. But, if you increase the roof pitch above 45°, then you are allowed to increase the pitch.
2. Choice of insulation. To reduce costs for insulation boards, it is recommended to take them into account standard sizes. Mats are produced in widths of 600, 800 and 1200 mm. If we neglect this condition, then it appears a large number of undercuts, cold bridges and construction will be delayed.
3. Quality of lumber. Here the type of wood, grade and section are taken into account. As mentioned above, strength is affected by how well the beam was dried. When purchasing wood, pay attention to the evenness and presence of defects in the form of knots and traces of pests.
4. Floor beams and tie rods. If you are installing under a gable roof attic floor, then the maximum distance between the rafters should be 0.75 meters.

The calculation of the distance between the beams for a gable and pitched roof is different. Even if he makes several slopes, for each it is necessary to make the calculation individually. This especially applies to buildings with different lengths of eaves.

Taking into account all these factors, you can determine at what distance to install the rafters. Although all calculations can be done independently, since reference data is freely available, it is better to turn to professionals. They have experience in design and will quickly determine the required distance between the rafters. Yes, you will avoid possible errors and you will be sure of safety.

Before installing the rafter system, the question arises at what step to install the floor beams. Correctly calculating the distance between the rafters means preventing subsequent deformation or even destruction of the roof frame. After reading the article to the end, readers will find out what the distance between the rafters should be for various types roofs 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 house construction, since often the upper link is 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 beams.

The span of the roof frame for the construction of a house made of timber usually exceeds 1 m, and the smallest permissible value is 60 cm, such indicators are indicated in GOSTs (see figure). You can correctly calculate the length of the rafters and their pitch using the following option:

Using a tape measure, the length of the roof slope is measured, the result is divided by the pitch 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 way you can 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 will be the distance between each rafter.

For example, consider a roof whose slope is 25.5 m and in increments 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 install the legs of the frame after 58 cm. This way you can easily calculate the pitch of any roof frame, single or complex, without taking into account the roof. But professionals recommend their calculations for a certain type of roof.

Rafter pitch depending on material

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

1. Profiled sheeting. It has different thicknesses and tropezoidal curve shapes. Costs from 120 rubles.
2. Ceramic tiles. Expensive material from 670 rubles. Has 12 color options.
3. Metal tiles. It's more cheap material unlike ceramic and costs from 320 rubles.
4. Ondulin. A soft roof insulates the house from rain, hail, etc. Costs from 340 rubles.
5. Slate. Most economical option from 90 rub.

We will consider the step size for the most common types of coverage below.

Spacing of rafter beams under corrugated sheeting

The distance between the roof beams depends on the size of the sheet that the corrugated sheet has. The pitch of the roof frame beams under the corrugated sheeting is standardly taken to be no less than 60 cm and no more than 90 cm.

If this distance is greater, then boards with a larger cross-section are attached between the rafter beams. The cross-section of the rafter legs under the corrugated sheet is selected 50x100 or 150 mm.

The most important thing to consider when planning to attach corrugated sheets is the sheathing. It is made from boards with a cross-section of 30x100mm; it must be mounted with a span of 50 cm. It depends on the brand and thickness of the corrugated sheeting and the slope of the roof.

So, a 15º roof, grade C 10 corrugated sheeting is mounted on a continuous sheathing, C 21 corrugated sheeting is mounted on the sheathing with a span of 30 cm. The largest corrugated board C 44 is mounted on the sheathing in increments of 50 cm to 1 m. In this case, before attaching the sheathing, you need to consider the free space chimney passage, ventilation hood and so on.

Spacing of rafter beams for ceramic tiles

Specifics of installation of the rafter system for laying ceramic tiles due to the weight of this roof. Ceramic tiles are made from clay, and this roofing weighs 9-10 times more than metal tiles. The calculation of the load on the rafter system for ceramic tiles is 40-60 kg/m2.

Beams for the roof rafter system for ceramic tiles are made only from dried material. The cross section is suitable 50x150 or 60x180 mm. The standard distance between the rafters for a tile roof is 80-120 cm. The span depends on the slope of the roof. At an angle of 15º, the span between the rafters is 80 cm, at 750 every 1 m 30 cm.

When calculating the step, 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 a minimum length of rafters, the step is maximum.

When laying ceramic tiles, it is important to consider that you will need to walk on the roof. The maximum safe 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. Standard Sheet The tiles are 40 cm long. Laying occurs with an overlap of 50 to 90 mm. When calculating the pitch of the sheathing, the size of the overlap is subtracted from the length of the tiles. The result is a pitch of 305-345 mm.

For a pitched roof for the construction of a house made of profiled timber, it is not difficult to make calculations. If the roof is complicated a lot pitched shape, then each distance between the rafters is calculated per lathing step separately. Having secured the cord to opposite side The roof slope can be easily marked with rows.

Features of the roof frame for metal tiles

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

Metal tiles weigh from 35 kg/m2 of roofing. This makes it possible to lighten the rafter structure and use beams of a smaller cross-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, holes with a diameter of 12-13 mm are drilled in the beams under the roof.

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

Features of rafter legs for ondulin

Ondulin is soft roof 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 is lightweight. This material is great for wooden houses both low-rise and large.

Rafter beams under the ondulin are placed with a distance of at least 60 cm, maximum 90 cm. For the rafter system, softwood timber with a section of 50x150 or 50x200 mm is used. A smaller cross-section will not provide sufficient strength to the rafter purlins.

The sheathing on the rafters is made of material with a cross-section of 40x50 mm in increments of 60 cm. This is quite enough for fastening sheets of ondulin with an overlap of 30 cm. Ondulin is fastened with special nails, which are sold as a set.

Features of the slate rafter system

Slate is rarely used for roofing modern houses. But in dacha construction and household This material is irreplaceable in buildings. It is low cost and easy to install.

Slate rafters

Slate rafter legs are used with a section of 50x100 or 50x150 mm. The fastening spacing between the rafters is no less than 60 cm and no more than 80 cm.

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

The pitch of the rafter system under slate differs in the roof structure. For households It is not uncommon for buildings to have a shed roof installed.

Feature of the size between the rafter beams on a single-pitched and gable roof

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

Single-pitch 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 specifics of a particular structure. The step between them can be 60-140 cm. The distance also takes into account whether the structure will be insulated. If yes, 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 material with a cross section of 50x100 mm. For a steep slope of 45º, stronger ones with a section of 50x150 mm are needed.

Gable rafter system

If you do not calculate the pitch of the frame of a pitched or other type of roof correctly, the roof may move away, and the beams will sag and bend due to the weight of the structure. In this case, simple repairs are not 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 sheets, ceramic or metal tiles, ondulin or slate, etc.

When building a roof, the first thing to choose is the type of rafter system. This means that the rafters must be hanging or layered, or the entire rafter system will consist of both rafters, i.e., combined. It is not difficult to calculate the distance between the rafters, knowing the magnitude of the loads that will act on the entire roof.

Loads can be temporary or permanent. TO constant loads relate:

• the weight of the materials of the rafter system itself;
• weight of roofing material;
• the weight of the elements of the roofing pie, if the roof is insulated;
• weight interior decoration attic ceiling.

Temporary loads include: weight of snow cover, weight of a person during production roofing works and roof maintenance during operation, wind load and the weight of possible water flows in the summer.

What are the calculations based on?

The distance between the roof rafters is also calculated based on the selected material and the cross-section of the rafters. All calculations are carried out at the house design stage by specialists from design organizations. To do this, they use reference documents and building codes and rules regulating this or that rafter pitch, sheathing pitch and other calculated values.

When building a private house, rarely does anyone order a project where, based on calculations, it is recommended what distance between the rafters should be maintained. Most often, developers rely on the experience of the craftsmen and trust them to carry out all the calculations on site. However, there are those who want to calculate the rafter system themselves and build the roof themselves.

In this case, they must first decide on the type of roof, choose what kind of attic it will be - heated residential or cold, since the type of rafter system and the calculation of the distance between the rafters directly depend on these parameters

Distance between rafters of a pitched roof

The calculation for a pitched roof is the simplest. The rafter system does not provide racks and braces - only the rafters themselves. This type of roof is most often installed on utility rooms, garages, bathhouses, etc.

The pitch of the rafters of a pitched roof is presented in the table below and depends on the cross-section of the timber:

If the developer wants to independently calculate the loads on the rafter system, it will be useful for him to familiarize himself with documents such as SNiP 2.01.85 “Loads and impacts” and “Changes from SNiP 2.01.85”, which contains maps of the climatic regions of Russia.

The material chosen for the construction of the rafter system is coniferous wood, the humidity of which is 20-22%. Boards, beams and other types of lumber must be smooth without curling, rot, knots or blue stains.

All wooden elements should be treated with antiseptics and fire retardants to protect the wood from rotting and fire. The material used, the length of the rafters and the cross-section of the timber also affects the calculations (see table):

Approximate calculation

The pitch of the rafters is nothing more than the distance between the rafter legs. As a rule, for residential private houses this figure is 0.6-1.0 m.

The pitch of the rafters is influenced by a significant number of factors. Calculation required quantity rafter legs are produced in the following way:

• The length of the roof slope is measured. After this, the resulting value is divided by the selected pitch between the rafters.
• Then one is added to the resulting value and rounded up to get a whole number. This is how the number of rafters required for a given length of one roof slope is obtained.
• After this, the entire length of the roof slope is divided by the resulting integer (the number of rafter legs) and as a result, the distance between the axes of the future rafters is obtained, which is called the rafter pitch.
• The axis should run through the center of the rafter. However for different types roof covering, the pitch of the rafters can vary, and it also changes depending on the slope of the roof slope.

For example: the length of the roof slope is 16 meters, and the pitch between the rafters is 0.6 meters. Therefore, 16/0.6 + 1 = 27.66 = 28 meters (rafters are necessary for the installation of the slope)

The greater the slope angle, i.e., the steeper the roof, the larger the pitch of the rafters can be made. This is explained by the fact that the load on steep roofs is not distributed over the entire roof plane, but is mostly transferred to the load-bearing walls.

Rafters for ceramic tiles

Ceramic tiles are a material that has a decent weight. Therefore, to install a tile roof, you should calculate the cross-section and length of the rafters, taking into account that one square meter of ceramics weighs almost ten times more than the weight of metal tiles.

• If the design of the rafter system involves tightening the rafters, then its cross-section should be increased.
• The rafters themselves should be made of dry, healthy wood, their cross-section should be 50x150 or 60x180 mm.
• The pitch of the rafters is made in the range of 0.8 -1.3 m for ceramic tile coverings, and its exact determination depends on the slope angle of the slopes.

The higher the roof, the wider the rafter spacing can be. For example, with a slope angle of 15 degrees, the step will be 80 cm, and if the slope angle increases to 75 degrees, the distance between the rafter legs will increase to 1.3 m.

Another circumstance affects the pitch of the rafters - the length of the rafter legs. The longer they are, the shorter their step. This is explained by the fact that when maximum length rafters are created increased loads for deflection. They can be reduced by installing a system of supporting posts, struts and other elements of the rafter system, which take on part of the loads from the rafters.

Metal roof rafters

The rafter system for metal tiles is not much different from other rafter structures. But due to the fact that it weighs several times less than ceramic tiles, rafters and all other elements of the roof structure can be made with a smaller margin of safety, i.e., a smaller cross-section. The difference in weight of clay and metal tiles is about 35 kg per 1 m2.

The rafter spacing for metal tiles is usually 0.6-0.9 m. Metal tiles are widely used for covering country houses, which often provide attic rooms, so the roof is made insulated. The pitch of the rafters in such structures is adjusted to the size of the insulation, which is inserted between the rafter legs.

The distance between the rafters of a gable roof is one of the most important parameters during its construction. It is this distance that affects the strength of the frame and rafter system; accordingly, the strength of the entire roof depends on it. To determine it correctly, it is necessary to make quite complex calculations. It is strongly recommended that you contact an architectural studio to carry them out. Incorrect calculations and, as a result, incorrectly chosen distance between the slopes can lead to serious negative consequences, such as deformation of the supports of the rafter system, deformation and violation of the integrity of the roof covering, roof collapse. Therefore, during the design process gable roof It is extremely important to use the most accurate initial data; reference values ​​must be taken strictly in accordance with the specific construction conditions, 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 during its construction.

Primitive method of calculation

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

1. First, the length of the slope along the eaves of the roof is measured (actually the length of the wall parallel to the slope + estimated protrusions).
2. The value obtained during the measurement is divided by the selected interval between the “legs” of the rafter system. Next, select the interval for which the “legs” will be separated. For example, 80 cm. In this case, the denominator of the fraction will be equal to 0.8.
3. The last stage: one is added to the resulting quotient; if the resulting number is not an integer, then it is increased to an integer, always in the direction of increase.

Such a simple calculation will allow you to determine the number of rafters, as well as the distances between the supports. It is important to remember that the obtained values ​​will determine the number of supports for only one of the two slopes. When the calculation is completed, the longitudinal size of the slope is divided by the estimated number of rafter supports. The result of this will be the exact distance between the supports. Let's 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 resulting value, we get 27.7. Next, we round up and in the end we have 28 pieces. rafters This is exactly how many “legs” the rafter system of one slope will have. Next, we determine the exact distance between them: 20/28 = 0.72 m. Using this simple method, you can determine the minimum interval at which the rafters will be placed. However, it is important to take into account what roofing material is chosen.

Return to contents

If corrugated board is selected

Corrugated sheeting is, although not heavy, but at the same time very flexible material. Therefore, the minimum allowable step for it should be 0.5 m, and the maximum should not exceed 0.9 m. At the same time, the frame of the rafter system must withstand not only the weight of the corrugated sheet, but also the sheathing. For profiled sheets, the sheathing is made of timber or boards with minimum size 30x100, the average installation step of the lathing should be 0.5 m (it depends only on the thickness of the sheet). The sheathing boards that extend onto the cornice when filling the corrugated board should be 1.5-2 cm thicker than the main sheathing. At the same time, it is important not to forget about the need for ventilation of the structure.

Return to contents

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 high specific gravity. If we compare metal tiles and ceramics, they differ in weight by more than 12 times. The weighted average pressure of such a coating is 45-70 kg per square meter of sheathing.

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

The frame with supports for such material should be made of well-dried timber, with approximately 15% humidity. For installation, beams of approximately 50x150 mm should be used (recommended 60x180 mm). Support pitch under 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 interval is taken to be minimal - 0.8 m. If the slope is inclined at 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 pitch value should be minimal. Short rafters require the largest possible spacing between them. You can move on the roof only if rafter step no more than 0.8-0.9 m with a slope of 45°. We should also not forget about the need for ventilation of such a structure.

For this purpose, holes are usually provided in the insulation, the diameter of which is in the range of 9-12 mm. The process of constructing a rafter system for metal tiles is similar to the process of constructing rafters for other types of covering.

It is important to remember that in addition to careful calculation required quantity The rafters should be calculated and the pitch for the sheathing.

It varies depending on the type of ceramic tiles. For example, the length of a ceramic tile is 0.4 m, while the joint overlaps 0.5-0.9 m. In this case, the sheathing pitch 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 truss structure absolutely the same (even if it is like this according to the design): errors and inaccuracies in the assembly can result in an error of 0.2 m.