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He cut down the rafters on the pitched roof. Rafter system of a pitched roof - reliability with precise calculations. Quantity of roof covering for a pitched roof

• Rafter system pitched roof in terms of assembly complexity it is one of the most simple options, and also the most economical in terms of material consumption. Therefore, this design is most often used for roofing utility rooms: garages, outbuildings, workshops and others. But this type of rafter frame is also used for residential buildings.

  However, despite the ease of assembly, in the design of pitched roofs, and even more so during their construction, it is imperative to comply with all the rules and requirements in accordance with SNiP. Why do you need to take the assembly of such a simple rafter system seriously, and what should you consider during the work process?

  What are the advantages of pitched roof types?

  As mentioned in the introduction, a shed roof is superior to gable roofs in terms of ease of construction. Such a roof can be erected even alone, and in a shorter time. In addition, there are many other positive points because of which it is worth choosing this option.

  1

  Significantly lower material consumption:

  2 Easy to install. All the work can be done by one person, because there is no need to assemble rafter pairs, and even more so to lift heavy parts to the place where the rafter frame is assembled. 3 Less weight of the structure. Due to the use of a small amount of materials, weight is reduced, which makes it possible to lay a lighter foundation for the entire structure. 4 Reduced wind load. Due to the lower silhouette, the pitched roof is not so susceptible to windage, and this does not create wind resistance. 5 Equipment for a residential attic (attic) is allowed. With appropriate design of the structure, it is quite possible to create an attic under a pitched roof. 6 Possibility of creating an exploitable roof.

  However, despite the many advantages, similar designs They also have negative qualities that do not always allow the use of these types of roofs. The main negative properties of single-pitch types of roofing structures are as follows:

  • Undesirable use in regions with big amount precipitation in winter period. In other areas of the country, accurate calculations are required, with careful selection of the cross-section of lumber.

  It is worth considering that such designs of rafter systems are more appropriate to use in southern regions with little precipitation and constant winds. To the north, you should not build a roof with a slope angle of less than 45 degrees.

  • Higher requirements for waterproofing.
  • A pitched roof is not always compatible with the chosen style and design of the house.

  Despite the disadvantages, pitched roof options are a popular option, especially in low-rise private construction.

  Design of pitched roofs. What to consider

  

  When planning the assembly of a pitched roof, you need to take into account and calculate many factors: the layout of the rafter system, the angle of inclination, loads, and select the appropriate materials. The result should be a drawing with complete information about the future roof.

  The classic scheme of a single-pitch rafter system consists of beams laid across the structure with a fastening to the beam installed along load-bearing walls. This is a so-called shed roof with simple layered rafters. But this option is only possible for spans with a length of no more than 4500 mm. However, it is permissible to use pitched roofs of greater length.

  

  • With a span width of 5000-6000 mm, the layered rafters need to be reinforced with struts, which rest on a load-bearing wall with an additional Mauerlat.
  • If the span width reaches 6000-7500 mm, you will need to assemble more difficult option– with an emphasis on the truss truss. A headstock is added to the structure, supporting an additional beam on which the rafter rests. Naturally, the racks (headstocks) are additionally reinforced with struts.

  In addition to choosing the layout of the rafter system at the project stage, you will need to plan the step between the beams, as well as their cross-section. Such parameters also depend on the width of the span and the length of the rafters used between the load-bearing walls. General recommendations are as follows:

  

  • When the length of the rafter beam is up to 3000 mm, its cross-section is selected within the range of 80×100 or 90×160 mm. The pitch between individual elements should be from 1100 to 2100 mm (depending on the cross-section!).
  • If the rafter is 6500 mm long, then a beam section of 120×220 mm is selected with a pitch between parts of 1100-1400 mm.

  But, in addition to choosing the appropriate section of rafter beams, and the assembly scheme is very important factor is the angle of inclination of the future roof.

  Selecting the slope angle

  

  The future functioning of the roof, as well as its strength, depends on the angle of inclination of the assembled slope. Optimal slope should ensure the removal of precipitation from the plane (especially snow), low wind load, as well as stable fastening of the roof deck.

  Calculation of the angles of inclination of all roofing structures must be carried out in strict accordance with SNiP 2.01.07-85 “Loads and impacts”. These building codes provide all the information on a specific region of the country.

  It is also worth considering the type of roofing material used, which is also recommended for use at different slope angles. For example, you can use the data from the table below.
  

  Do not forget that in regions with high rainfall in winter, the most optimal location of the slopes is 45°.

  When choosing slope angles and roofing material, you need to take into account that planes with slight slopes will have to be cleared of accumulated masses of snow, so it is best to choose a flooring that can withstand the weight of a person without subsequent deformations.

  Assembly of various options for pitched roof truss systems

  Single-pitch types of rafter structures are most often used to cover ancillary buildings: garages, sheds and outbuildings. How is the assembly work carried out?

  Shed garage roof

  Typically, the span width of garages rarely exceeds 4000 mm, so above this building you can use the simplest scheme rafter frame. Assembly is carried out in stages as follows:

  
  

  • The Mauerlat is made from timber with a cross-section of at least 100×150 mm. The part should not move closer than 50 mm to the outer edge. The element is secured to studs pre-embedded in the masonry. If the structure is made of wood, then the function of the Mauerlat is performed by the upper crown of the walls.
  • It is best to prepare a template of the appropriate length for the rafters in advance. Moreover, it is desirable that initially the timber be a little larger (50-100 mm from each edge) from the planned length. The required overhang of the cornices is formed after installing the rafters, cutting off the excess edges. Typically, roof overhangs are made within 400-500 mm on each side.
  • Along the entire length of the mauerlat, markings are made for the notch for the rafters. The step between them is in accordance with the project. The wood is sampled to a depth not exceeding 1/3 of the thickness of the timber.

  

  • The manufactured rafters are installed in their places and connected to the Mauerlat using the chosen method (nails, staples, corners, etc.).
  • Upon completion of installation, the rafters are trimmed to the required length and covered with a padded wind board.
  • To form the roof overhangs in front and behind the garage, you can use two methods.

1. The Mauerlat is carried out to the required length beyond the walls of the building.
2. Additional elements - fillies - are attached to the outer rafters.

On a note

Accordingly, the sheathing for the roofing is then made!

Formation of the rafter system of the extension

Extensions to a house can have different parameters, and with a span width of less than 4000 mm, you can use the classic scheme with the rafters supported on two load-bearing points. However, with wider buildings (˃4000 mm), it will be necessary to install struts that rest against the wall of the building.

• On external wall In the extension, a mauerlat made of 100×150 mm timber is laid. The part is fastened using the chosen method (on studs, anchors), in wooden building the part is not mounted using the upper crown of the wall as a support for the rafters.
• In the opposite wall of the house, under the rafters, you need to prepare nests to match the size of the rafters in the thickness of the wall (such grooves can be made at the masonry stage).

The rafter system of a pitched roof refers to simple designs. It attracts with its reliability and economical consumption of material. Construction pitched roof It is permissible to do it on our own and can be done in a short time.

It is popular for garages, outbuildings and sheds. Residential buildings are less often covered with a roof with one slope, but such options are found when implementing original architectural ideas for constructing a building. Despite the simplicity of the design, the work on creating a roof is a very important stage and requires adherence to technology.

The rafter system diagram for a small building is quite simple: inclined rafters laid on the Mauerlat cover the distance between end walls. The span of the building in this case is no more than 4.5 m. The angle of inclination of the slope is determined by the difference in the height of the opposite walls. This can be achieved in two ways:

install special supports on one of the walls under the upper edges of the rafters;
when conducting masonry load-bearing structures perform one higher than the other.
When the slope is oriented, the low part of the roof is directed towards constant winds, this will ensure the resistance of the frame to high loads.

The function of the rafter frame is to redistribute constant and emerging loads on the roof between load-bearing walls. Her constituent elements are:

• Mauerlat - a beam at the base of a structure connecting it to the walls of the structure;
  rafters - a board or beam that forms the basis of the frame;
• struts, racks, supports - elements that strengthen the structure with a span of 6 to 9 m;
• lathing - slats packed at a distance determined by technology are the basis for roofing and strengthen the rafter system.

A single-slope structure is characterized by less windage than systems with a large number of slopes, but when designing it, it is necessary to take into account the weight of the snow cover. This is especially true for roofs with a small slope of 8-10 degrees. When creating drawings, the location and size of all elements of the rafter system, as well as installation diagrams for frame components, are noted.

The distance between the rafters of a pitched roof is recommended within 60-80 cm, this ensures sufficient strength for any coating used. The presence of overhangs 25-40 cm long on each side of the building guarantees the drainage of rainwater from its walls, eliminating their erosion.

Advantages of a pitched roof

1. The consumption of lumber is significantly reduced compared to more complex structures.
2. Construction costs are reduced.
3. Big choice roofing materials as a finishing coat.
4. You can install the rafter system yourself in a short time.

How is the angle of inclination determined?

The slope of the slope is one of the main parameters of the roof. The intensity of the load on the rafters directly depends on this indicator. Main selection criteria:

1. Amount of precipitation in the region.
2. Type of roofing.

A large angle contributes to the unhindered melting of snow, but leads to additional consumption of material. A slight slope reduces the impact of wind, but requires frequent clearing of snow from the roof. Optimal angle is also related to the type of roofing; for each material there is a recommended parameter in degrees:

• metal tiles - 25;
• slate, ondulin - 20;
• roofing felt and others rolled materials- from 5 to 10;
• corrugated sheeting - 20;
• natural tiles - 35.

Preparation of lumber before installation

The service life and reliability of the roof depend on the quality of the lumber used in the construction of the frame. It is recommended to use dry timber from coniferous species. The wood should not have knots or damage. Before installation, it undergoes mandatory treatment with an antiseptic and fire retardant; these compounds protect against rotting and fire. The size of the beam depends on several factors:

• span length;
• the amount of load on the roof (snow, wind, etc.);
• slope angle.

The section of boards for rafters is 50×150 mm, 60×180 mm, timber for mauerlat 150×150 mm, for lathing 50×50 mm.

Stages of installation of the rafter system

The construction of the frame begins with laying the Mauerlat. Before installation on the walls, the timber is wrapped in roofing felt for waterproofing. The base is attached to the studs laid during laying or using anchor bolts.

The rafters are installed on a fixed Mauerlat. For strong fixation, it is necessary to make cuts on the boards. To ensure that all inserts are the same size, they are made according to a template. Top part cut with a bevel, allowing the rafters to bend. The lower notch serves as a strong support for the Mauerlat.

The roof rafters are fastened using nails and corners screwed with self-tapping screws. You can simplify the installation of the frame by installing the outer rafters and stretching a rope between them to define the plane.

If the length of the purlin is more than 4.5 m, the brace is installed at an angle of 45 degrees, one of its edges rests on the rafter, and the other on the mauerlat.

The end of the installation will be filling the sheathing. Its bars are located perpendicular to the frame, the fastening step depends on the finishing coating. For roll material continuous lathing. Used for coating moisture resistant plywood or OSB boards.
After installing the rafter system, a waterproofing sheet is laid and the roof is insulated. The final stage of work is installation of the roof covering.

So, in order for the structure to serve for a long period of time, to be strong and also reliable, it is worth thinking not only about the foundation, but also about the roof. Construction system such an element plays a huge role, because it is the roof that takes on the negative aspects of changes in weather conditions, as well as other situations.

The rafter system of a pitched roof must be characterized by certain requirements, including:

• Rigidity
• Little weight
• High quality material

Such requirements must be taken into account so that the structure lasts a long time.

The rigid characteristics of the element play important role, because it is with the help of rigid elements that different parts are connected. Such elements should not be subject to deformation processes, as well as expansion under any circumstances.

The basis of this design is a triangle, which is made using a special reliable frame. Each element of this frame is fixed to one another in parallel, and with the help of strong fixation the stability of the entire structure is ensured.

Rafter system of a pitched roof: diagram

But if such frames are poorly attached and movable, this will only lead to negative consequences . Such a roof can collapse not only from strong winds, but also on its own.

If we talk about weight, then this the roof should not be heavy. That is why this system is made, in most cases, from wood. If the weight is large enough, you need to do load-bearing base made of metal.

There are cases when use coniferous trees, the humidity of which is not less than 18 percent. Among mandatory conditions when using trees, note:

1. Antiseptic treatment
2. Use of flame retardants

Only in this case, the nodes in the area of ​​which the entire system is precisely fastened will be distinguished by high strength and reliability.

High quality of materials used is one of the main rules. The tree must meet the following characteristics:

• Applies 1-3 different varieties . It is important to pay attention to ensure that there are fewer cracks and knots. Per meter of material, 3 knots with a height of no more than 3 centimeters are allowed. Cracks are also allowed in a minimum amount, but not throughout the entire depth.
• It is advisable to make elements of a load-bearing nature from parts whose thickness is at least 5 cm and whose area is at least 40 m2.
• Boards from coniferous trees can only be used with a length of no more than 6.5 meters, and for deciduous trees - up to 4.5 m.
• It is advisable to make pillows, purlins, and also the Mauerlat from trees that belong to hard deciduous species. Such material should be pre-treated with one or another high-quality antiseptic.

Shed roof design

So, before starting to manufacture the system, it is very important to know what its main parts are:

1. Mauerlat, which can be called the foundation of the system. Using this part the load is distributed evenly and correctly.
2. Run represents an element that confidently fastens all the legs of the rafters. The ridge version is at the top, but the side elements are located on the sides.
3. The rafter leg is installed to determine the angle of inclination of the slope, as well as for the reliability of the entire roof, its appearance. It is this product that fixes individual parts of the system.
4. Tightening helps keep feet in place, do not move apart. This part connects them at the bottom.
5. Racks, as well as struts give additional foot stability.
6. Lathing It consists of boards, as well as cut beams. It is stuffed perpendicularly, transfers the load to the rafter legs.
7. The overhang of the entire roof protects against precipitation.
8. Horse is the place where two roof slopes meet. It is along this element that the lathing is packed, due to which it occurs strengthening one or another part of the roof.
9. fillies are used when the length of the legs is short, as a result of which they create an overhang.

ATTENTION!

Only by taking into account the described parameters will you get a reliable roof.

A shed roof is characterized by the presence of one slope, which is characterized by an angle of 14 to 26 degrees. In the case when the roof is made for small house, then the span will not exceed 5 cm, so it is recommended to make a layered system.

The support of such a roof is made on external walls, as well as on a wall that exists inside the object. Rafter systems are used in cases of rafter trusses.

Roofing pie, or rather, its design, depends on which final version of the coating will be chosen. But, regardless of the material, this element Maximizes the “life” of the roof, durability.

The lean-to type requires special attention, since it is this stage of construction that has the greatest influence on the climate of the structure.

Rafter system design

Fastening the rafters of a pitched roof

The fastening scheme is quite simple, as it consists of parallel boards that rest on two walls. To install the legs, special transition elements are used, which are made of wood.

Depending on what material is used, the following can be used as a transition piece:

• Mauerlat. In the above single-slope roof system, these are two wooden beams, which lie separately and complete the walls.
• Upper foot, which is made of beams.
• Upper harness the entire frame.

Although the design of this roof is simple, there are some subtleties of fastening the rafters that are important to know about.

The fact is that the nodes that are used must take into account all the negative aspects of a material such as wood.

When designing, the following tasks should be taken into account:

• The ability to easily move wooden parts from one another
• Adaptation to the consequences that may occur after the subsidence of each wall in order to take a stable position
• Elimination of all possible causes of failure of one or another connection

The triangles are fastened according to the following scheme: the horizontal side is installed on the Mauerlat and fixed. It is very important that it has a sufficiently large area for docking with other elements.

It is important to install the rafter legs at a certain angle to the supporting elements. It is worth understanding that two points are not enough for strong fastening, so there are methods that are used to avoid negative consequences.

First of all, it is important to increase the total interaction area of ​​the rafters, as well as the supporting part using:

• Select cuts
• File the upper as well as the lower edges of the legs. With the help of such actions, you can easily create a support platform and increase stability.

Fastening the rafters

Rafter pitch

The distance between the rafters of a pitched roof is calculated depending on what material is chosen, as well as the cross-section. Such calculations should be done at the stage used building regulations, rules.

The calculation for the above roof option is very simple. There are no racks or braces here; as a result, only the rafters of the pitched roof are taken into account.

Usually, for such a roof, Coniferous wood material is used, the moisture factor of which is approximately 20-22 percent. Such boards should be characterized by evenness and the absence of blue.

Each blood material is characterized by its own characteristics, so the pitch of the rafters is also different:

1. Using distance depends on sheet size. Typically, the beam spacing is at least 60 cm and up to 90 cm. For larger distances, additional boards with a larger cross-section of 150 mm are used. It is important to take into account the use of lathing, the cross-section of which should be 30*100 mm, and installation is carried out taking into account a span of at least 50 cm.
2. often used, but its weight is taken into account. Beams for such a system are pre-dried. When determining the step size, the length of the boards should be taken into account. At maximum length It is worth making the minimum distance between the rafters. The same rule is used with a minimum length of beams - a large step distance. Typically, 80 cm is considered a safe step.
3. Under, which is used much more often than the two above materials, beams with a small cross-section are used. The step in this case is equal to a number from 60 to 90 centimeters. Timber should be used with a cross section of about 50*150 mm.
4. Using it is worth understanding that this in the form of sheets. Beams should be placed with a distance that will not be less than 60 centimeters, but not more than 90 centimeters. The cross-section of the timber is 50*200, and 50*150 mm can also be used. When using a smaller section, negative aspects can be expected, since such a section will not be able to provide high strength to the legs.
5. Under , which is used very rarely, rafter legs with a section of 50*100.50*150 are used. The pitch is no less than 60 centimeters, and no more than 80. In this case, the pitch differs depending on the roof structure.

Rafter pitch table

Installation of the rafter system

When deciding to install the rafters of a pitched roof yourself, you should first prepare all the elements and also treat them with special means.

The boards should be laid on both sides of a certain roof and placed in the grooves.

Only after this is it important to attach several outer rafters.

CAREFULLY!

Please note that it is important to hammer one or two nails into each joint. The legs are installed taking into account the previously stretched strings, after which they are nailed in the same way. After this, the sheathing is installed, and the roof is laid.

After calculation and design, there are certain stages of installation:

• Installation of supporting beam. Big beam laid along the wall of the object. It should first be planed and soaked in antiseptic.. It is important to lay roofing material along the end of the wall, and mount the timber on it level using anchor bolts.
• Processing of timber and rafter elements. The board is planned to extend above the roof overhang - a level of about 40 cm on each side, depending on. It is important to consider that the steeper the angle, the less it costs to make an overhang. When using metal tiles and corrugated sheets, the step is 120 centimeters. In cases where the width is more than 6 meters, it is recommended to reduce the step to 1 meter. The board is embedded into the Mauerlat for strength.In contact with

  The pitched roof is rightfully classified as one of the simplest and most economical designs. She attracts minimum consumption materials and a simple construction process. The construction single-slope option can be the first confident step on the path of an independent roofer.

  However, without compliance with technological requirements, there will be no positive outcome even in the most basic matters. In order for the result to please you with reliability, you need to know what the truss system of a pitched roof is and what requirements must be taken into account when constructing it.

  Shed roofs are a faithful companion to domestic buildings, terraces, garages, attached and free-standing verandas. Above residential buildings In the vastness of the Fatherland, they are still extremely rarely built, although the number of adherents of the Art Nouveau and high-tech styles is touching with an upward trend.

  Despite belonging to the pitched category, pitched roofs still cannot be unconditionally called attic: the space under the roof is too small to organize the premises. And since it doesn’t make sense to use the attic, then separating it from the building with a ceiling is not always advisable. Therefore, in practice, builders of pitched roofs often install spacers and rafter legs instead of roofing.

  In a simplified way, the rafter frame of a pitched roof can be called a slab laid at an angle or a half of a layered system, which is much closer to constructive essence. It is constructed exclusively from layered rafter legs, i.e. from rafters with reliable supports for the upper and lower heels.

  Among the options for supporting the rafter legs of pitched roofs are:

  • Two load-bearing brick, concrete, wooden walls different heights. In this case, the rafters of a pitched roof rest on the walls through a mauerlat laid in two unconnected strips. Support can be made through concrete reinforced belt, pre-designed and installed during the construction of the walls, as well as through the upper rows of timber or log boxes.
  • One load-bearing wall made of concrete, wood, brick and supports located opposite. It is clear that extensions and sheds are built in this way. The upper edges of the rafters in such cases rest on steel brackets screwed to the load-bearing wall or to sockets selected in it. The lower heels rest on the harness connecting the support pillars.
  • Two rows of concrete, brick, wooden supports. Both heels of the rafters rest on the harness. Moreover, the supports can simultaneously serve as elements for fastening the sheathing and forming frame walls.

  In private construction, shed structures are most often used if the span they cover does not exceed 4.5 m. Covering a more serious span is quite possible: to implement it, you will simply need to strengthen the system with purlins, supports, and struts.

  However, among private owners there are few fans of such large-scale pitched roofs, so we will consider the simplest representatives and the principles of their construction. Having understood their design, you can create your own project by modernizing and making additions.

  

  A well-designed project takes into account the need to place a single slope on the windward side so that the roof is not torn off and carried away by gusty winds.

  

  Average sizes of components

  For the manufacture of layered rafters, forest and lumber of the 2nd grade are used. Sanded logs and plates are suitable - the same logs, but hewn on both sides. Timber and boards sewn in pairs are used.

  The cross-section of rafter legs for the construction of pitched roofs over buildings must be calculated taking into account the weight of the roof, snow and wind loads. Among folk craftsmen, the listed values ​​are simply added up and entered into one of the many calculation programs, of which there are a little less than a legion on the Internet. In order not to struggle with calculations, we will present the average sections of rafter legs and related elements used for the construction of pitched roofs in middle lane, This:

  • Logs and plates cut from them Ø 180-200mm, timber 100×150mm (150×150mm) are used to construct a rafter frame covering a span of 4.5 m or more.
  • Logs and plates Ø 120-180mm, timber 100×100mm are used if it is necessary to cover a span of up to 4.5m.

  In both cases, it is permissible to replace the timber in pairs with sewn boards, the dimensions of which will ultimately make it possible to obtain a beam of the required section.

  

  It should be remembered that logs with a diameter of less than 120 mm, plates with a thickness of less than 70 mm and boards with a cross-section of less than 40×150 mm are not used in the construction of rafter structures. Even for low-impact sheds installed on sites in the middle zone, the indicated dimensions are a minimum.

  If the diagram of the truss system of a pitched roof predetermines the design of the purlin, it is installed parallel to the slopes. It is needed to increase the rigidity of the structure as an additional support system. To fix the purlin, install supports and support exactly as dictated. Only the goal is not to form a ridge fracture, but to maintain the plane of a large slope. The purlins of long-span structures are made from timber 180×180mm or from logs Ø 200-260mm. To make racks for purlins, take a beam with a side of 120 mm or a log 130-200 mm in diameter.

  

  Step of a lean-to rafter system

  The installation step of the rafter legs is determined in accordance with the geometric data of the box being equipped. The slopes on which the rafters are to be supported are divided into equal sections so that the distance between the rafters is the same. The breakdown of slopes for their installation is carried out taking into account the size and type of materials used:

  • For rafter legs made of timber, log plates, the installation step is from 1.5 m to 2 m.
  • If the rafters are made of paired boards, the installation step is from 1 m to 1.75 m.
  • For rafters made from a single board, the installation step is from 0.6m to 1.2m.

  The choice of installation step for the rafter legs of an insulated roofing structure is influenced by the size of the insulation. It is very convenient if they are installed rigidly between the rafters, with slight squeezing. This is very economical solution, because they do not need to be laid in two layers, and heat loss is eliminated, due to the elimination of the causes of the formation of cold bridges.

  
  

  Do not forget that if you increase the recommended distance between the rafters, you will have to reduce the installation step of the sheathing or even make it continuous. Such a choice is not always advisable from the point of view of both labor costs and construction costs. It is better to adhere to technological recommendations and calculate in advance what is more profitable: install one or two fewer rafters or strengthen the sheathing of the slopes.

  As is customary in the construction of pitched roofs, the rafters are attached to the wooden wall crutches or stuffed in brickwork plugs with anchors. Fixation is carried out through one rafter leg with twists of annealed wire. The attachment points of the rafter legs to the walls are located 20-30 cm below the Mauerlat. Wire twists can be laid during brick laying. It is allowed to fasten with brackets to walls made of timber or logs.

  
  

  Options for single-pitch rafter frames

  To better assimilate the information, let’s look at several common examples of constructing rafter systems for pitched roofs. Let's consider simple construction projects, the construction of which can be handled by a skilled owner.

  Design #1 – single-pitched garage rafter frame

  Let us analyze the structure of the rafter frame of a pitched roof over a garage, the walls of which are made of foam concrete blocks. The reinforced belt recommended by the standards was not poured, which is why the procedure for laying the Mauerlat remains. In single-pitched roofing structures it is constructed in the form of two beams laid on walls of different heights.

  

  The process of constructing a rafter system in stages:

  • We lay 100x150mm timber flush with the internal planes of the high and low walls. This is the Mauerlat of a pitched roof. Because the timber will be in contact with the foam concrete; it will be laid on a roofing felt or similar waterproofing pad. We fasten the timber approximately 80cm apart with 90×90 roofing corners, reinforced with a cast lintel. We screw the corners with Ø 14mm dowels.
  • We will make a rafter template from a board with a cross section of 50×200mm. Let's install it on the Mauerlat so that there is a margin of about 55-60cm on both sides. The margin should be slightly larger than the planned width of the eaves overhangs. Usually it is 40-50cm. After installing all the rafters, we will trim off the excess.
  • We mark the points of future cuts on the installed workpiece, not forgetting that the cutting depth should be no more than 1/3 of the width of the board.
  • We mark the walls so that the outer rafters on both sides do not touch concrete wall. It is advisable that there be a distance of 4-5 cm between the wood and concrete.
  • We make rafter legs according to the template, install them and fasten them to the Mauerlat with brackets or corners.
  • From the scrap board we make a pattern of fillets taking into account the width of the overhang. We make all the cornice elements using the template. Then we install, not forgetting about the waterproofing gaskets between the wooden parts and concrete wall.
  • We cut off the excess rafters and nail a wind board with a cross-section of 25×100mm around the perimeter.

  Elementary truss structure ready for the garage. Remaining by installed rafters fill the sheathing under the covering of the pitched roof. It can be continuous or sparse. The installation step of sparse laths depends on the type of roofing material.

  

  In the first example, we formed the eaves overhangs by installing fillets. There is a slightly different method, according to which the Mauerlat beams are installed outside the perimeter of the box. The offset is equal to the width of the eaves overhang. The rafters are positioned so that the outermost elements are just above the edges of the mauerlat. Short extensions are installed in the space between the outer and adjacent rafters. Further everything follows the standard plan.

  

  Design #2 – pitched roof over an extension

  No less often than the previous example, the task of constructing an extension to an existing building arises. For obvious reasons, the roof will be pitched. It will fit perfectly into any architectural and landscape conditions, and will not create a threat of precipitation accumulation.

  The rafter system is being constructed at an angle of 20º, because will be produced on top of it. The rafters will rest on the main one and located opposite brick wall extensions. In the example of a lean-to structure we have proposed, a span of 4.75 m must be covered, which is more than 3.5 m. This means that to ensure rigidity, the installation of struts will be required. The design and installation of struts is carried out with the condition that the angle of their inclination is not advisable to exceed 45º.

  The section of the board for making rafter legs is 50×200mm. They will be installed after 70cm. We will make the struts from 50x150mm boards, and for the construction of the sheathing we will stock up on 25x100mm boards.

  

  Algorithm for constructing a single-pitch rafter frame:

  • We install 100x150mm timber flush with the internal plane of the extension wall, not forgetting to first lay down waterproofing. We fix the beam with bolts every 80-100mm.
  • IN main wall At the planned height, we hollow out grooves for installing the upper heels of the rafters. The depth of the grooves is 12 cm, the width is slightly greater than the thickness of the board, the pitch is 70 cm. Instead of hollowed-out grooves, you can use metal brackets that are simply screwed to the wall. In shape they resemble an inverted letter “P”, in which the upper edge of the rafter is located.
  • Let's make a template for the rafter legs. We place the 50x200mm board in its designated place and mark the cuts on both edges. The depth of the top cut required to install the rafters in the groove is 10 cm. There is no need to go deeper, otherwise the rafter will rest against the wall, and this is undesirable. We transfer the dimensions of the top cut to the bottom. At the same time, we mark a vertical cutting line along the width of the cornice.
  • Using the template, we make all the rafter legs and install them in their proper places. For fastening at the top we use metal corners, one side of which is screwed to the wall, the other to the rafter. We fix it at the bottom with corners or brackets.
  • We try on a piece of board against the main wall and one of the rafter legs to determine the point for cutting the groove for the strut. Do not forget that the angle between the wall and the strut should not exceed 45º, and the lower heel of the strut should rest against the wall 20-30 cm below the opposite wall.
  • Stepping back from the imaginary vertical drawn through the upper groove by 5-6 cm in any direction, we hollow out the bottom row of grooves. We place them every 70cm.
  • We cut off the lower corner from the strut blank so that the cut line is 10 cm.
  • We try on the workpiece, placing the edge with a notch in the lower groove. Along the line of intersection of the rafter leg and the workpiece, we draw the upper cut.
  • According to the verified scheme, we make and install all the struts. We fasten them to the rafters with metal toothed plates.
  • We form cornices by installing fillies on the inclined walls of the extension. Do not forget about the mandatory waterproofing between the brick or concrete wall and the roof elements made of wood.
  • We sheathe the perimeter with a wind board and install the sheathing.

  The technology given as an example is valid not only for installing pitched roofs over capital extensions. Covered verandas with terraces and utility blocks are arranged in a similar way.

  
  

  The work progresses much more happily if the walls of the main building are made of timber, logs, or made using the Canadian frame method. It is commonplace to install brackets under the upper heels of the rafters: there is less hassle and the process moves much faster.

  

  Design #3 – lean-to structure for a shed

  A pitched roof is an excellent option for arranging outbuildings, temporary buildings, and summer kitchens. Rare units need the fundamental nature of such structures. The simplest options are in greater demand, the construction of which can easily be completed by the owner of a suburban plot.

  Let's consider installing a pitched roof over a small shed for storing summer cottage equipment. Its walls were built according to the frame-greenhouse principle by installing vertical posts connected at the bottom along the perimeter by strapping. The front and rear walls of the barn differ in height, so they are connected not by a single frame, but by separate transverse strips.

  The cross member of the high wall is laid at an angle, which eliminates the need to make cuts to support the upper heels of the rafters. To form an angle, the high wall posts are sawn from above at the designed angle.

  

  The algorithm for constructing a rafter system is typical. First, a piece of board is applied to the end of the building and the cut lines are outlined. Then it is filed according to the template required amount rafter legs. They are installed traditional way according to the markings made on the walls in advance. To fasten elements of the rafter system over light domestic buildings, nails or self-tapping screws are sufficient. Screw or hammer hardware products at an angle, trying to ensure that there are no gaps between the parts being connected.

  The wind board is fastened around the perimeter after installing the wall sheathing. The example barn does not have eaves overhangs. However, if desired, you can make them by installing rafters with a length that takes into account the formation of overhangs. It is planned to lay a soft roof, under which a continuous sheathing will be installed. The dimensions of the sheathing made of plywood, GVLV, boards or OSB-3 are determined by the outer plane of the wind board.

  

  The angle of inclination is small, so the use of waterproofing is highly desirable even if getting the items stored in the barn wet is not too much of a concern. Waterproofing will protect wooden parts buildings from rotting and subsequent inevitable failure.

  The video will show you the process of constructing a rafter system for a pitched roof:

  We looked at the most typical examples that are relevant and accessible for personal execution. Described in detail technological nuances typical situations. This basic options, which may well become the basis for our own developments. Dimensions vary due to individual needs, but the principles of construction rafter frames stable for pitched roofs. Knowing them is useful for both independent craftsmen and owners who want to competently supervise the work of builders.

  The distance between the rafters is one of the key parameters affecting the strength of the structure. Proper calculation of the installation pitch of the rafters allows you to build a roof that is resistant to high operating loads.

  Roof loads and calculation of the rafter system

  The development of a project for a single-pitch or gable roof begins with choosing the type of rafter system, the angle of inclination of the slopes (roof height) and materials for constructing the structure. Calculation of the distance between the rafter legs is carried out taking into account the loads that the roof will experience during operation. Constant loads include:

  • the weight of the materials from which the rafter system is made;
  • roofing weight;
  • weight of roofing materials (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:

• weight of snow cover;
• the weight of a person during roof maintenance and repair.

The pitch refers to the distance between the rafters of one slope. When calculating a single slope, gable or complex roof, usually follow 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 at what distance the rafter legs should be placed. Determining the step cannot be extremely accurate, since it is necessary to take into account whole line additional factors, including the width of the insulation, the installation features of the sheathing under different kinds 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 subsequently remove part of the rafters and install a supporting structure, such as a special rafter system.

Distance between rafters under slate

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

The optimal solution is to install a system under 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 sheathing is made of timber or boards with a cross-section of at least 30 mm. When calculating a rafter system for slate, you should read that this material has quite 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 install the rafters, it is necessary to take into account the loads and the angle of the roof. Metal tiles are characterized by their relatively low weight, thanks to which they can serve as a replacement for old slate or roofing coverings. ceramic tiles. In this case, the rafters will not need to be strengthened or the pitch of their installation changed.

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 you intend to use insulation, the layer of which in areas with low winter temperatures should be 200 mm, for rafters under metal tiles it is recommended to use 200x50 timber so as not to install additional system holding the insulation. It is better to adjust the gap between the rafters for metal tiles to the width of the sheet or roll insulation.

Corrugated sheeting: rafters and sheathing

Corrugated sheeting is a lightweight and easy-to-use roofing material. Galvanized or coated with a decorative protective layer, corrugated sheets can be used for installing a pitched roof utility room or a garage, or for a gable roof of a residential building. How to calculate the distance required to install rafters under corrugated sheeting?

To ensure the necessary structural rigidity, it is enough to install the rafters under the corrugated sheets in increments of 600-900 mm. In this case, you need to pay attention to the angle of the roof. Calculations show that under high external loads, it is better to lay corrugated sheets on the system with a minimum step. But if the distance between the rafters under the corrugated sheet is close to the maximum, and the roof slope angle is small, then the structure is strengthened by using more frequent sheathing. In this case, the pitch of the sheathing under the corrugated sheet should be about 50 mm, the width of the elements should be at least 100 mm.

Rafter system for soft roofing

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

The minimum distance between the rafter legs is 600 mm, the maximum is 1500 mm. When installing a support under 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 continuous sheathing should be. The choice of step is also influenced by the thickness of the material for the sheathing - the thicker the sheet of plywood or OSB, the larger the installation step of the rafter legs can be.

Ondulin: calculation of rafters

Ondulin (bitumen slate) is laid on a flat, continuous sheathing made of sheet material. This allows the roofing covering to successfully resist wind and snow loads. The sheathing 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 pitched roof.

Rafters for ondulin are made of timber with a section of 200×50 mm. When choosing at what distance to place the rafter legs for the structure under the ondulin, it is recommended to take into account the width insulation material to make it easier to install. This calculation allows you to reduce the financial costs of roofing.

Sandwich panel roof

Sandwich roofing is most often erected on houses made of sip panels or hangar-type buildings. A special 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 top of the wall (or the distance between supporting structures pitched roof) allow the installation of a sandwich without additional supports.

If the span exceeds 4 meters, additional purlins must be installed. To install a sandwich roof on a residential building, a traditional rafter system is often installed, but in this case, the rafters can be positioned at larger intervals - they serve as a support for the purlins. 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. Technical specifications sandwich allow the roof to withstand high operating loads.

Polycarbonate: construction of a supporting structure

Polycarbonate in Lately is actively used as a roofing material. First of all, polycarbonate is in demand in the construction of gazebos, canopies, and winter gardens. The lathing and rafter system for polycarbonate can be made of wood or metal.

Polycarbonate varies in weight depending on the thickness of the sheet. It is recommended to perform lathing under polycarbonate in increments of 600-800 mm. The sheathing (wooden or metal) is mounted on the rafters, which can be straight or have arched shape. Typically, the gap between rafters for polycarbonate is from 1500 to 2300 mm. In order to correctly calculate at what distance it is better to lower the rafters, it is necessary to take into account the glazing area, the size and thickness of the sheets, and take into account that polycarbonate is attached with gaps for thermal expansion.

The distance between the rafters of a gable and pitched roof

Find out what distance between the rafters needs to be made for a gable and shed roof. The maximum distance between rafters for metal tiles, ondulin and soft roofing.

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

The task of correctly calculating the distance between the rafters is a very important one. How seriously you begin to solve this problem will determine not only the reliability and durability of the roof, but also all subsequent work on it: laying insulation, installing roofing, installing additional elements. If you manipulate the pitch of the rafters under the roofing sheets, as many do, then it is not a fact that insulation will then fit between the rafters. If you focus only on insulation, the very first winter with its abundant Russian snow will crush the rafter system. That’s why the whole point is to choose the optimal rafter pitch for all slopes, and this is the skill we’ll teach you now.

What determines the pitch of the rafters?

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

1. Roof shape (gable, single-slope or multi-slope).
2. Roof angle.
3. Parameters of the timber used to make rafters (width, thickness).
4. The design of the rafter system (sloping, hanging or sliding).
5. The totality of all loads on the roof (weight of covering, atmospheric phenomena, etc.).
6. Lathing material (20x100 or 50x50) and its parameters (solid, with gaps of 10 cm, 20 cm or solid plywood)

And each of these parameters needs to 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 in winter the roof of a residential building can withstand a large cap of snow, a constant wind at altitude, and it is often insulated from the inside, but completely different requirements are placed on the rafter system of a small gazebo hidden under the treetops.

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

The illustration above shows that even such a building has its own pitch of rafters. After all, here it provides both the aesthetic factor and the rigidity of the structure itself. But they choose a step arbitrarily.

Functional rafters: detailed calculation

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

Point 1. Wall length and choice of rafter spacing

The first step in installing rafters on the roof of a residential building is usually chosen structurally based on 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 for a wall 6 meters long, 7 rafters are installed as a standard. At the same time, you can save money by placing them at a distance of 1 and 2 meters, and you will get exactly 5 rafters. It can also be placed at a distance of 2 and 3 meters, but reinforced with lathing. But it is extremely undesirable to make the rafter spacing more than 2 meters.

Point 2. The 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 regular roof is 1 meter. But, if the area has a significant snow or wind load, or the roof is more or less flat or simply 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 1.2 m-1.4 m.

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 turbulence occurs there, after which the wind hits eaves overhang roofs. It turns out that the wind flow seems to bend around the slope of the roof, but at the same time trying to lift it. And at this moment forces arise in the roof that are ready to tear it off or overturn it - these are two windward sides and one lifting one.

There is another force that arises from wind pressure and acts perpendicular to the slope, trying to press the roof slope inward. And what larger angle the slope of the roof slope, the more important the safe wind forces and the less the tangential ones are. And the greater the angle of the slope, the less often you need to install rafters.

This map of the average wind load will help you understand whether to make a high roof or a flat one:

The second point: in the Russian region, the standard roof of a house is constantly exposed to such atmospheric phenomena as snow. Here too, you need to take into account 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 continuous sheathing. The easiest way to identify such places is by the wind rose: single rafters are placed on the windward side, and paired rafters are placed 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:

Point 3. The issue of insulation and standard width swear words

If you will be insulating the roof, then it is advisable to place the pitch of the rafters under standard sizes insulation slabs, which are 60, 80 cm and 120 cm.

Modern insulation materials are now sold in standard widths, usually at the same standard rafter spacing. If you then take them and adjust them to existing parameters, then there will be a lot of waste, cracks, cold bridges and other problems.

Point 4. Quality and strength of the lumber used

It is also of great importance what kind of material you use to build the rafter system. Thus, for each type of wood there is its own regulatory documentation that concerns its load-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 prescribed. If you use wood of other species, you can derive a correction factor.

In addition, if the rafters have sections, notches or holes for bolts, in this place the load-bearing capacity of the beam must be calculated with a coefficient of 0.80.

Point 5. Distance between tie rods and floor beams

One more point: if the roof is built with interconnected trusses, and their lower chord is used simultaneously as floor beams, then the distance between the trusses should be within 60-75 cm in order to take into account the design of the future floor.

Point 6. Loads on rafters

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

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

And all these factors are capable of influencing the roof simultaneously at a certain moment, and therefore there is such a thing as critical value. This is exactly the load value at which the roof cannot withstand and becomes deformed.

Therefore, if a building is being built with significant spans, then steel roof trusses must be used. The fact is that there is no longer any tension 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 design of the roof itself.

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

Point 7. Weight of the rafter system and roofing pie

Do not forget that the main purpose of the rafters is to support the entire roof, and its weight is decisive:

Point 8. Ease of installation of roofing

The distance between the rafters is also influenced by factors such as the selected roofing covering. The higher the roof slope, 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 continuous sheathing? 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 at the edges need to be fastened directly into the rafters or sheathing, and it is important that they coincide. Otherwise, the work of covering the roof will easily turn into a living hell at altitude, believe me.

That is why, even before starting installation, you must make a layout and 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 rafters 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, the snow cap, wind pressure. After you add all the loads together, be sure to multiply them by a factor of 1.1. So you all plan for the unexpected favorable conditions, that is, to provide an additional 10% percentage strength.

Now all you have to do is divide the total load by the planned number of rafters and see if each of them can 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 have peace of mind for your home.

You need to make calculations for destruction, i.e. for the full load acting on the roof. All these loads are determined according to the technical characteristics of the materials and SNiPs.

The standard roof structure consists of rafters, lattice purlins, and each of these elements responds only to the load that puts pressure on it, and not on common roof generally. Those. Each individual rafter is subject to its own load, total, but divided by the number of rafter legs, and by changing the step of their location, you change the area where the load is collected on the rafters - reducing it or increasing it. And, if changing the pitch of the rafters is inconvenient for you, then work with the parameters of the section of the rafter legs, and the overall load bearing capacity the roof will increase significantly:

When making this calculation, try to ensure that the longest rafter in your project is no more than six and a half meters, otherwise, splice along the length. Now let's explain in more detail. So, on roofs with slopes up to 30 degrees, the rafters have so-called “bending elements”. Those. they work specifically for bending, and there are certain requirements for them. And the possibility of rafter deflection is calculated using 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 “bending-compressed” elements. That is, they are affected not only by a uniformly distributed load, which causes the rafters to bend, but also by forces that are already acting along the axis of the rafters. Speaking in simple language, here the rafters not only bend a little under the weight of the roof, but are also compressed 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 handle such calculations. The main thing is to take everything into account, be attentive and ready to spend a little more time on design, so that then all the work goes like clockwork!

Distance between rafters: what step should be between rafters

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