The high popularity of this roofing option is due to its simpler design compared to other types. This factor is especially important for beginning builders, as well as for those who want to cope with such a task completely independently without resorting to hired teams. Most often it is used to cover extensions on a site (garages, barns or bathhouses), but it can just as successfully be erected on any residential building without any loss in terms of constructive use.

Options for rafter system schemes and types of rafters

1. Layered variety.

In this embodiment, ordinary or composite rafter legs rest on the load-bearing walls of the building. To reduce the load on large spans (more than 4.5 m), intermediate supports are arranged (the middle of the leg is supported by a rafter leg, one end of it is placed directly under the main leg, and the second rests against the post). The roof structure with a layered variety of rafters is used most often, including on pitched roofs (on simple outbuildings, sheds, country houses etc.). The main points and connections of rafters for pitched roofs are shown in Figure 1.

2. Hanging variety.

In this embodiment, the main legs rest on their own tightening; excess load is weakened by introducing inclined supports and racks. This design is not assembled immediately in a designated place, but on a plane, after which it is lifted and installed in place. If the distance between the supporting walls is too large without the presence of intermediate objects between them that could be used as supports, this is the only option for installing the roof, i.e. they are mainly applicable to gable roofs in buildings without internal load-bearing walls. There are a number of special metal fasteners on sale that are designed for hanging rafters and make them easier to assemble. The features of this design and the main components are presented in Figure 2.

layered rafters of a pitched roof (Fig. 1)
hanging rafters (Fig. 2)

3. Sliding variety.

In this embodiment, the main legs rest with one end on a log at the ridge of the future roof, and with the other end rest against the supporting walls. The connection to the walls is not carried out directly, but through the use of special sliding joints (Figure 3). This installation method is used mainly only in wooden buildings to compensate for its shrinkage. If the connections are not movable, then when the supports are displaced, the entire system may be destroyed. However, it is worth noting that such compounds are used quite rarely.

Rafter system: advantages and disadvantages.

Advantages and rules for installing a pitched roof truss system with diagrams

The advantages include:

• simple installation, compared to other types of roofing systems,
• lower material costs,
• reliability of the design,
• an unusual design if used for residential buildings, since this design is mainly used in country houses, utility rooms, etc.

sliding fastenings (Fig. 3)
Vacation home with a pitched roof (Fig. 4)

rice. 5
simplified diagram of the rafter system of a pitched roof (Fig. 6)

For residential buildings the disadvantage of such a roof there will be no full attic or attic, installation of additional waterproofing to prevent possible leaks at a small roof angle, for non-ventilated options with small angle tilt to negative points also include the need to care for the roof during the snowy period. Examples country houses, which have one slope, are shown in Figures 4-5.

The complexity of execution and the grandeur of a multi-gable roof.

A diagram of the truss system for a pitched roof is being developed. taking into account the following indicators:

1. The distance and placement relative to each other of those walls that were chosen as supports, i.e. span length.
2. General design, purpose and shape of the building that will be covered.
3. The amount of precipitation in the region and wind loads.
4. The presence of intermediate walls, arrangement of the attic floor.
5. Total weight roofing, including the rafter system, sheathing and roofing.

The schemes of the rafter system of a pitched roof will differ from each other depending on the design design, which takes into account all of the above factors. Some circuit options are shown in Figure 6-7.

rafter system depending on the span length (Fig. 7)
example of connecting a rafter with a mauerlat (Fig. 8)

The final diagram of the truss system for a pitched roof should reflect the following:

1. Angle of inclination. The first step is to calculate the angle of the roof.

2. Material of the rafter system. Most often this is wood (boards, poles or beams). Section and diameter depends on bearing capacity all frame elements. Most often, a 50x150mm board is used for the legs. Racks, struts and tie-downs are selected with a cross-section commensurate with the cross-section of the rafters (at least 120 mm). All structural parts must be made only from dry wood, which has been additionally treated with antiseptics

3. Roofing material. The choice of material for the roof is also carried out at the very beginning, since the calculation of the angle of inclination of the plane depends on it. The heavier the weight of the covering material, the greater the angle of inclination. The roofing covering must be reliable, durable, and resistant to precipitation. Also, the appearance of the building and the final cost of roofing work depend on the choice of coating.

4. Lathing. The frequency of lathing crossbars is determined by the weight of the mounted roofing(and features of its installation) with an increase in expected weight winter precipitation. There are solid and frame sheathing. The first option takes the form wooden flooring from boards. The second option is suitable for tiled and metal roofing, consists of bars (50x50 mm) with a pitch of at least 50 cm.

5. Connections and fastenings. Durability and reliability are determined not only correct calculations, but also the strength of all connections. Mounting example rafter legs to the Mauerlat can be seen in Figure 8.

example of the construction of a simple pitched roof, stages 1-6 (Fig. 9)
stages 7-12 (Fig. 10)

Installation takes place in the following order:

1. First, the seismic belt is installed, on which the main beams are then laid.
2. Afterwards, the main rafter legs, beds and racks, and grips are mounted.
3. Then they move on to arranging the sheathing. The distance between elements is dictated by the selected roofing material.
4. The final stages are laying the roofing material and insulating the structure.

The listed main stages can be seen in the example of construction garage roof in Figures 9-10.

This design allows for significant savings consumables, compared to other options, it can take almost three times less wood. Due to the lack of a high angle, the room under the roof is smaller in size and much easier to heat, which means it can be used not only as a storage room. It is better to cover buildings erected in open and windy areas in this way in order to avoid heavy loads on the roof planes.

• Rafter system of a 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 also this type 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 aspects that make it 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 allowed residential attic(attics). 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 a lot of advantages, such designs also have negative qualities, not always allowing 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 high rainfall in winter. 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 low rainfall 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 fastenings installed along the 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 the following:

  

  • 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 rafter beams, and the assembly diagram, a 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. The optimal slope should ensure the removal of precipitation from the plane (especially snow), low wind load, and 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 different angles falling stingrays. 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 slopes are 45°.

  Selecting the slope angles and roofing material it is necessary 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 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.

• A mauerlat made of 100×150 mm timber is laid on the external wall of the extension. The part is fastened using the chosen method (on studs, anchors); in a wooden structure, 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 single-pitched rafter system came to us from the USA and Europe. Residents using it noted its reliability and low cost, so the popularity of this type spread very quickly. Despite the fact that a small amount of wood was required to build one slope, few people dared to undertake such construction. The fact is that the majority of developers considered such a system too simple for residential buildings, and the other part simply did not know how to build it, in order to prove the opposite. In this article I will try to explain to you how to easily and quickly create such systems and correctly select the pitch of the rafters of a pitched roof.

Basis of calculations

Despite its simplicity, one slope must meet all installation rules. After all, if you make serious mistakes, the roof covering will become deformed, which will inevitably lead not only to leaks, but also to the collapse of the entire roof.

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

1. Reliability of fastening the rafter legs to the support beam and ridge;
2. Correct selection of auxiliary parts for the rafter system;
3. Durable lumber and auxiliary elements;
4. Rafter step.

Don’t think that by observing just four points you will achieve the most stable structure. To do this, you will have to use all known methods and technologies.

Values ​​for calculations

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

Roofing material parameters

Rafter foot step

Rafter slope

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

• Rafter legs
• Lathing
• Roofing pie

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

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

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

How to calculate the required distance between rafter beams

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

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

1. First of all, you need to find the full length of the roof. This value should include any ends and overhangs;
2. We divide the resulting value by the maximum allowable distance between the rafters;
3. We round the answer up. This number will indicate the number of spans;
4. Next, take the roof length and divide it into spans. This way you will find the optimal step;
5. And to find the number of rafter legs, you need to add one to the spans.

This rule works for the vast majority of roofs, but there are also those that cannot be calculated in this way. If this is your case, you will have to get an additional rafter at one of the ends.

Rafter system depending on roofing covering

It's no secret that the greater the mass of the roof covering, the greater the number of rafter legs that need to be installed. Most manufacturers of this material indicate in the instructions for their product optimal quantity rafters and their sizes.

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

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

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

Rafter system for corrugated sheets

Roofing corrugated sheets lightweight material and at the same time has good strength characteristics. Therefore, small-section lumber can be used as rafter legs, but with frequent steps: 0.6 - 1.2 meters. The roof slope should be at a slope of 12 to 45 degrees.

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

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

Lathing for corrugated sheets is arranged discharged method, and the pitch of its elements should be 50-80 centimeters. However, these values ​​may go beyond due to the characteristics of the roofing itself. You can also find tips on how to arrange these parts in the instructions included with the purchased material.

Rafter system for ceramic tiles

Ceramic tiles are a unique roofing covering. It is made of clay, which makes this material very heavy. Designed rafter systems must comply with the following requirements:

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

Rafters for metal tiles

Due to the fact that metal sheets are significantly thinner, you do not have to install a serious rafter system. Therefore, you can safely follow the advice and recommendations of roofing material manufacturers.

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

Rafter structure for ondulin

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

The rafter system for ondulin must meet the following parameters:

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

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

Rafter system for corrugated asbestos-cement sheets (slate)

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

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

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

Rafter system of one and two slopes

IN Lately the pitched roof is gaining more and more popularity. This is understandable, because materials are only becoming more expensive, and you really want to save money. Thanks to simple design it can be done. The rafter system of one slope is quite primitive. To do this, you just need to place the beams on the crown and secure them. Of course, do not forget about the insulating material.

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

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

But you shouldn’t play around with calculations, because this can lead to an increase in windage and consumption of lumber. The most optimal slope slope for gable system– 45 degrees.

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

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

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

A pitched roof is quite rightly classified as one of the simplest and most economical structures. She attracts minimum consumption materials and a simple construction process. The construction of a single-pitched version 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 separately. standing verandas. They are still extremely rarely erected above residential buildings in the vast expanses of the fatherland, although the number of adherents of the modern 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 floor laid at an angle or half of a layered system, which is much closer to the structural 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 load-bearing wall or to the slots 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, it will be possible to create own project through modernization and 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. Listed values ​​in environment folk craftsmen they are simply added up and entered into one of the many payment 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 supports in exactly the same way 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 plots 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 objects construction, 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 the 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 them around the perimeter wind board cross section 25×100mm.

Elementary truss structure ready for the garage. All that remains is to fill the sheathing along the installed rafters 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 brick wall of the extension located opposite. 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 the 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 permanent extensions. Covered verandas with terraces and utility blocks are arranged in a similar way.

The work progresses much more fun if the walls of the main building are made of timber, logs or made according to 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, 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.

Consider the construction of a pitched roof over small barn for storing garden equipment. Its walls were built according to the frame-greenhouse principle by installing vertical racks, 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.

Cross member 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. These are basic options that can easily become the basis for your own developments. Dimensions change due to individual needs, but the principles of constructing rafter frames for pitched roofs are stable. Knowing them is useful for both independent craftsmen and owners who want to competently supervise the work of builders.

For the construction of small buildings and houses there is no need for a roof complex configuration. A truss system of a pitched roof can be adopted as a design solution. In this case, the scheme is simplified, but some nuances appear.

Advantages and features of a single-pitched system

The advantages include:

• simple calculation;
• reducing the number of nodes and connections;
• simplified installation;
• reduction in wood costs;
• maintainability.

A pitched roof is resistant to external negative conditions, inexpensive and easy to install

When deciding to make such a roof with your own hands, you need to take into account the following features:

• the need to erect high longitudinal walls of the building or special frames;
• the difficulty of using the under-roof space as an attic space;
• it is necessary to locate a house or building on the site so that in most cases the wind blows on the high wall of the building (you need to familiarize yourself with the wind rose of the construction area);
• The angle of inclination is taken depending on the coating material used.

The scheme includes the following main elements:

• two mauerlats;
• rafter legs.

For large spans, you will need to install additional elements yourself to secure the load-bearing beams and increase their load-bearing capacity:

• rafter legs (struts);
• racks;
• runs;
• lying down;
• contractions.

All elements are made of wood coniferous species first or second class. To choose the right one suitable material you need to pay attention to the following points:

• felling location (it is better to choose northern regions);
• time of felling (a tree cut down at the end of winter - beginning of spring will be stronger).

System calculation

Before you start assembling the structure with your own hands, you need to make a calculation and select the correct cross-section of all elements.

Installing a roof is a responsible process in which mistakes should not be made.

Depending on the width of the building and the required section of the rafter leg for the designed span, select constructive solution rafter system.

Selection of section

When a house is erected by professional builders according to a pre-prepared project, a calculation is made based on two limit states, which determines the height and width load-bearing beams according to two requirements:

• rigidity;
• strength.

When building a private house with your own hands, you don’t have to perform the calculation, but you need to take into account the recommendations depending on the span. Rafters on a pitched roof are always layered.

1. Span up to 4.5 meters. The scheme involves the use of solid rafter legs, without bracing with struts or racks. It is also convenient to use if you plan to install an attic: it allows you to increase free space due to lack intermediate supports. The recommended cross-section of the rafters at a pitch of 0.6 m is 50x150 mm; for a pitch of 1.1 m, an increase to 75x175 mm will be required.
2. Span up to 6 meters. In this case, everything depends on the angle of inclination and span. In some cases that's enough standard length boards or beams - 6 m. With a large angle of inclination and a span approaching 6 m, it will be necessary to join the rafter legs along the length. As additional support, struts (rafter legs) are provided. At the point where the strut joins the rafters, the leg is joined lengthwise. The recommended cross-section at a step of 0.6 m is 50x200 mm, at a step of 1.1 m - 100x200 mm.
3. The span is more than 6 meters. In this case, you need to make intermediate racks that will take on part of the load and reduce the sagging of the beam. Correctly install the supports so that each span of the rafter leg is less than 6 meters. In this case, the calculation is performed as for a multi-span beam, taking into account intermediate supports. When building with your own hands, the cross-section is taken in the same way as for a span of up to 6 m (previous point). In this case, all rafters are composite.

If you plan to lay insulation between the rafters yourself (warm attic, attic), then the calculation takes into account minimum height beams

The thickness of the insulation should not be greater than the height of the rafters for polyurethane foam, polystyrene foam and extruded polystyrene foam.

If you plan to install mineral wool, then additionally take into account ventilation gap 5 cm. It is provided partly by the load-bearing beams, and partly by the counter-lattice, which is mounted on top of them.

Selection of beam pitch

The pitch of the rafter legs depends on the following factors:

type of thermal insulation material;

Availability skylights.

In the first case, the dependence is inversely proportional. The design of a pitched roof involves reducing the rafter pitch as the span or load increases. For the type of insulation, the following recommended values ​​for the distance between the rafters in the light (clean) can be given:

• polystyrene foam and extruded polystyrene foam – 0.6 m;
• mineral wool – 0.58 m;
• polyurethane foam - the step does not depend on the insulation.

When designing an attic and using skylights as light sources, it will be necessary to ensure that the rafter spacing is 4-6 cm greater than the width of the window in the places where they are installed.

Tilt angle

Roof slope angle

Depending on the type of roofing used, it is allowed to take different angles slope of the roof slope. Below are the values ​​for the most common materials. It is important to remember that the steeper the slope, the lower the likelihood of leakage and the load on the elements, but this complicates construction and requires the construction of a high longitudinal wall.

1. Ceramic tiles. The optimal tilt angle is 30-45 degrees, acceptable is 12-65 degrees.
2. Bituminous (soft) tiles. Optimal - 20-45 degrees, acceptable - from 6 degrees.
3. Metal tiles. Optimal - 20-45 degrees, acceptable - from 12 degrees.
4. Galvanized roofing steel. Acceptable - from 14 degrees.
5. Slate. Acceptable is 6-27 degrees.

The smaller the angle of inclination, the less consumption materials for construction, but this increases the load on the roof and the likelihood of leaks.

Work order

After the calculation is completed, we begin purchasing the material and assembling the structure.

1. Treating elements with an antiseptic. This can be done after installation in the design position, but if you plan to store the wood, you need to process it immediately after purchase.
2. Waterproofing areas of contact between materials with different properties. Where the mauerlats are laid on a brick or concrete wall you need to lay a layer of roofing felt, linochrome or waterproofing.
3. Laying the Mauerlat and securing it to the wall. Can be done on wire, staples, studs, anchor bolts.
4. Laying rafter legs. Fastening them to the Mauerlat. Can be fastened using staples, nails or corners with self-tapping screws.
5. Installation of waterproofing and sheathing.
6. Laying insulation.
7. Roofing covering.
8. Installation of the bottom sheathing and ceiling trim.

It is important to correctly select the scheme of a pitched roof, the cross-section of elements, the pitch of the rafters and the angle of inclination. Compliance with the technology of doing the work yourself will ensure the reliability and durability of the structure.