In any building, the main elements on which the maximum load falls are the foundation, walls and roof. The quality of the roof installation largely depends on whether the truss system is installed correctly or not. If the attachment points of the truss system do not meet certain requirements, then such a roof will not last even a minimum operational period without repair work.

Requirements for the truss system

The truss system of any roof must meet such important requirements as:

• Maximum rigidity. Any frame node must withstand loads without being subjected to deformation or displacement. The triangle obtained during the arrangement of the truss system must ensure the rigidity of the structure and its maximum stability;
• Optimal weight. Depending on the roofing material choose the material used for the rafters. Usually choose wooden beam, but for heavy roofs, metal can also be used.

  Important! To prevent damage to the rafters, their rotting and the formation of fungus on the wood, it is treated with an antiseptic, and metal constructions- anti-corrosion compounds.

• The high quality of the materials used. The wood used as rafter legs should not have cracks and chips.

Varieties of truss systems

The roof can be equipped with one of the types of truss system, of which there are only two:

• Hanging rafters;
• Overhead rafters.

Hanging truss system

Such a system is optimal in the case of a gable roof, when the span between the walls is no more than 6 meters, but when installing additional elements, it is also applicable for wider openings. The Mauerlat serves as the lower basis for the support, while the upper part of the structure abuts against each other. This design also contains a puff - necessary to relieve the load from the walls, by reducing the expansion of the rafters. Beam puffs are installed below the rafter legs and can serve as floor beams.

Attention! The role of tightening can optionally be performed by a wooden beam, it can also be an overlap made of reinforced concrete structures, which in some houses is equipped with an upper floor.

If the puff is located above the bottom of the truss system, then it is called crossbar. Important points in the arrangement of this type of truss system include:

• The roof overhang should not be allowed to rest on the lower part of the rafter legs, which extend beyond the wall. In such a situation, it is best to use a filly (the width of the overhang is set within one meter). With this arrangement, the rafter will be based on the Mauerlat. The cross section of the beam for the filly is chosen smaller than for the rafters;
• To give the roof additional rigidity, and prevent it from staggering and being destroyed by strong gusts of wind, a wind board is nailed on the slope, to the Mauerlat from the ridge;
• If the moisture content of the material used to equip the truss system is more than 18%, unsteadiness should be foreseen, which will cause gradual drying of the wood. That is why fastening should be done with bolts or screws, not nails.

Layered truss system

This arrangement is applicable for roofs with distances between walls from 10 meters (maximum 16 meters). The slope can be made at any angle, and inside the building there are load-bearing walls or supporting columns. From above, for the rafters, the ridge run serves as the main support, and from below this function is performed by the Mauerlat. The inner purlin is supported either by the inner wall or by the studs. Due to the presence of only vertical type of loads, there is no need to install the tightening.

With a 16-meter span, the replacement of the ridge run is carried out by two side structures, the support for which will be the racks.

Important! The absence of bends in the rafter legs is ensured by such nodes as struts and crossbars.

Particular attention to the arrangement of the roof using a layered truss system should be paid to such nuances:

Features of calculations of the gable roof truss system are shown in the video:

The main nodes of the truss systems

The main nodes of the roof truss system include:

• Rafter. They perform the function of a skeleton, supporting the internal and external elements of the roof, and also serve as the basis for laying communications;
• Mauerlat. This is a kind of roofing foundation, which is a beam on which the entire structure is installed. It performs an important function - uniform distribution of the load of the entire structure;
• Run. Designed for fastening rafter legs together and can be located both on top and on the side;
• Puff. Serves for fixing the rafters in the lower part of the structure;
• Struts and racks. Provide the most stable location of the rafter beams;
• Skate. The junction of the roof slopes;
• Filly. These are continuations of the rafter legs, which are sometimes equipped;
• Rigel. It is necessary for high-quality and reliable support of load-bearing elements;
• Sill. cross bar needed to distribute the load.

In addition to the listed elements, the design includes attachment points for the roof truss system. When performing them, it is necessary to follow certain rules.

Important! It is absolutely not worth performing a simple fastening of the base to the crossbar, as this can lead to the complete destruction of the truss system.

The following types of fasteners should be used:

• With emphasis on the end of the crossbar;
• Teeth point-blank;
• Teeth in a spike.

The number of teeth should be chosen depending on the slope of the slope, and additional structural reliability can be created using metal corners.

To the main attachment points roof structure relate:

• Beam knot;
• Mauerlat knot;
• Skate knot.

beam knot

With such a node for connecting elements, an insertion of teeth into a spike is made into the rafter, and a recess corresponding to the teeth is made in the transverse section of the crossbar. Such a recess or nest should not exceed 30% of the timber thickness.

Fastening is carried out with special hardware with metal corners, or wooden beams, spikes and overlays.

Attention! If the roof is made of materials with low weight, and the slope of its slope does not exceed 35º, then the bases of the supports should be placed so that they rest against an area larger than the beam itself.

Mauerlat knot

Such fastening can be performed both by rigid technology and by sliding technology. Rigid technology involves the installation of a strong connection between the Mauerlat and the rafters, preventing the possibility of slipping, deflecting or popping out. For this, special support corners with bars are used. The resulting knot is fastened with wire using hardware. At the same time, nails should be hammered obliquely so that they enter the wood crosswise. The last nail must be driven in vertically.

In the case of a sliding fastening, alignment is performed using a special mechanism that allows you to move the rafter leg in the required direction. To do this, a tie-in is made on the supports, on which the Mauerlat is then laid. The structure is fixed, as in the previous case, with crossed nails. This method of arranging the connection nodes allows all nodes of the truss structure to move within certain limits.

Attention! Rigid fastening with inexperience of builders can lead to damage to the walls of the building.

ridge knot

In this case, the fastening can also be made in two types - butt and overlap. With a butt joint, the top of the supports is cut with a bevel, as is the angle of the roof. They rest on the same undercut opposite supports. Fastening is carried out using nails, in the amount of two pieces. They are hammered from above at a certain angle. The seams that form between the supports are connected with metal plates or plates. In the second case, fastening is carried out by overlapping, not by end parts, but by lateral sections and fixed with bolts.

Conclusion

When performing work on the installation of the roof, the arrangement of the truss system should be given careful attention, avoiding violations technological processes. This will provide the structure with strength, durability and reliability.

Rafters and lathing - the roof frame that bears the brunt roofing cake, thermal insulation, snow load, therefore, they must have a high bearing capacity, strength. The idea of ​​using metal rafters to make the roof structure more rigid is not new, but in the past it was mainly used to cover industrial or utility structures. Now the rafter frame and the metal profile crate are considered a real alternative to wooden roof elements if the slope length exceeds 10 meters.

The design of the roof truss frame consists of many interconnected elements that form trusses. The step, the size of the section between the rafters and other supports determines the calculation of the loads to which they are subjected during operation. The roof frame performs the following functions:

1. Load distribution. Interconnected nodes, reinforced with corners, evenly distribute the weight of the roof, which can reach up to 500-600 kg, taking into account the snow load. How larger section rafters and less step between them, the greater the bearing capacity of the structure.
2. Giving slope and shape. The rafters, located at an angle to the base of the roof, form an inclined plane of the slopes, so that snow and water do not accumulate on the roof surface.
3. Formation of the base for fixing the roofing material. Fastening finish coat roofing pie goes to the roof frame. The crate acts as a basis for fixing the coating, distributing its weight evenly over the rafters.

Note! What should be all the nodes, rafters and lathing of the roof structure determines the engineering calculation. To determine the required bearing capacity of the frame, it is necessary to calculate the total load to which it will be subjected. To do this, add up the weight of the roofing material, insulation, waterproofing, the maximum snow load with the weight of the truss system.

Types of truss systems

The most common material from which the crate and rafters of the roof frame are made is wood. However, if the weight of the roofing material is large enough, and the length of the slope is more than 6 meters, then the structure is too massive. Builders have to reduce the step between the rafter legs, increase their cross section, which is why the roof nodes acquire a lot of weight, increasing the load on the foundation. You can unload the load-bearing walls and the base of the building using stronger, but lighter metal rafters. According to the type of material used the following types truss systems:

• Wooden. Rafters and lathing made of wood are used for the construction of roofs, the slope length of which does not exceed 7-10 meters. The frame elements are fastened together using self-tapping screws, nails or movable metal elements. The step between the legs is usually in the range of 50-80 cm.
• Metal. Metal roof frames are made of zinc-coated steel profile, which is not afraid of moisture. The rafters and the crate made of this material are light, durable, so the step between them can be increased to 1.5-2 meters. The fastening of the metal profile is carried out by welding or fasteners. Metal roof units are used with a slope length of 10 meters or more.
• Combined. The truss frame, combining metal and wooden knots, is called combined. The combination of wooden and galvanized steel support elements allows for a cheaper structure with a high load-bearing capacity by increasing the spacing between the rafters.

Please note that metal and wooden elements frame can not be connected to each other without a gasket made of waterproofing material or antiseptic treatment. Since the metal has a high thermal conductivity, its proximity to the tree leads to the formation of condensation and rotting of the rafters.

Fastening methods

Metal rafters are assembled into triangular, trapezoidal or arched trusses. Internal stiffeners are attached to the frame beams, which form corners that significantly increase the load-bearing capacity of the frame. Such a system allows you to take a step between the rafters more, taking into account the support capabilities of each truss. The fastening of the metal elements of the roof frame is carried out by one of the following methods:

1. Fastening by welding. If you weld the details of the truss system using a welding machine, you can get a rigid structure with high strength and bearing capacity. If you correctly calculate the roof, you can lighten the frame and reduce the load on the foundation of the structure. The disadvantage of this method is that only a professional with the help of special equipment can perform welding.
2. Fastening with bolts. Fixing the rafters with fasteners allows for less rigid fastening. This method of assembling a truss frame based on a metal profile is used in private housing construction, where the length of the slopes does not exceed 10 meters. Rejection of welding allows you to speed up the installation of the roof.

Experienced craftsmen rely on the fact that the rafters can withstand more weight than wooden ones, so you can increase the step between them and reduce the thickness of the section of the elements. Moreover, in construction stores ready-made roof trusses are sold, the fastening of which was carried out by welding, suitable for overlapping buildings of standard width.

Advantages

The metal truss frame is used for the construction of roofs of any shape, any slope with a slope of 1-2 degrees. As the material from which the rafters and lathing are made, steel corners, pipes of round and rectangular cross-section, and tauri are used. In order to correctly select the thickness of the frame elements and choose the step between them, the calculation of the roof structure is performed, taking into account the permanent and temporary loads that are transferred to the rafter beams during operation. The advantages of the rafter system from this material are:

• Fire safety. Unlike wood, metal beams frame is not the country of ignition, which increases the fire safety of the building.
• Ease of maintenance. Zinc galvanic coating, which covers the steel corners, protects the roof frame from corrosion during the entire service life. They, unlike wooden ones, do not require annual antiseptic treatment.
• Zero waste. Although metal structures are quite expensive, it is considered cost-effective, since the fastening is carried out by welding, and there is practically no waste left.
• Long service life. If you correctly calculate the loads, then the metal roof frame will last more than 100 years, which exceeds the life of even the most stable roofing.

Professional roofers believe that it is advisable to use welded metal structures for the manufacture of a roof truss frame with a slope length of 10-12 meters. In this case, the main task is to correctly calculate the loads, and then determine the step between the legs in accordance with the climatic characteristics and properties of the roofing material.

disadvantages

Despite the obvious advantages, metal truss systems are not the most popular design solution in private housing construction. Even a large step between the rafters and a sparse crate at a high cost of metal cannot make the structure cheaper than wood. The disadvantages of metal rafters are:

1. High thermal conductivity. The metal has a high coefficient of thermal conductivity, so the rafters and form bridges are cold. From the point of view of energy efficiency, a metal profile frame is not the best solution.
2. Difficulty in transportation and installation. When choosing a metal rafter system, take into account that transporting, lifting and securing long and heavy elements is more difficult than standard length lumber rafters.
3. Difficulty of installation. To rise to a height and fix the trusses, special equipment is used, the rental or purchase of which is expensive.
4. Deformation under high temperature. Although metal is considered non-combustible materials, during a fire, it is severely deformed, which usually leads to the collapse of the roof.

To determine whether it makes sense to use more expensive metal profile truss elements, you need to calculate the roof frame. If the slope length exceeds 10 meters, and the load is more than 450-600 kg, then the installation of a metal frame is economically feasible.

Video instruction

In addition to correctly made calculations and drawings, fasteners for rafters and all its elements are of no small importance in the stability of the structure.

In addition to the load of atmospheric precipitation, the rafters must withstand the weight of the crate and total weight roofing cake, which must be taken into account when choosing a fastener.

The truss system is spatial design, consisting of the following elements:

• Mauerlat;
• rafter legs;
• valleys;
• ridge beams;
• runs;
• crate.

In order to understand how all parts of the truss system are attached to each other, you need to figure out what nodes it consists of, what fasteners are used in each case and what they are. When assembling load-bearing structure roofs are used fasteners, both steel and wood.

The main nodes of the connection of the truss system

Before connecting the Mauerlat and the rafter leg to each other, the first one will need to be firmly connected to the wall. Mauerlat is a thick beam (15x15), laid along the axis of the wall and parallel to the ridge of the beam, on which the rafter legs rest. The functions assigned to this element of the supporting structure are to distribute the load from the rafters, the weight of the roofing pie and atmospheric precipitation throughout the wall, including internal supports. In other words, the Mauerlat is the foundation for the entire roof. It is laid on the axis of the wall and fixed to it. In this case, there are several connection methods.

Method one. When constructing a roof of a large area, an armored belt is poured along the entire length of the wall, where metal pins are immediately embedded under the M12 thread every 2 m. this method as fasteners for the Mauerlat with the wall there will be studs that pass through the beam through and are attracted to the wall with a nut and washer. With a small area of ​​\u200b\u200bthe roof, where there is no large load on the wall, they do without a Mauerlat and the rafters are attached directly to the studs embedded in the masonry process.

Method two. Another quite affordable way to make the truss system stable is to fasten the Mauerlat to the wall with a wire. To do this, you need to lay the middle of the wire between the rows of bricks 3 rows before the end of the masonry. Its length should be sufficient to tie and pull the Mauerlat to the wall. You can also do without the Mauerlat and fix the rafter with wire directly to the wall. But such a connection will give a point load on the wall, which may affect its integrity.

The scheme for attaching the rafter leg to the Mauerlat can be rigid and sliding. The type of connection depends on the shape of the roof and the type of rafters, which can be hanging or layered.

Rigid and sliding connection of the lower part of the rafters with Mauerlat

Connection nodes in this case will be made of wood and can have several types:

1. A tooth that has only an emphasis.
2. A tooth with a spike and an emphasis.
3. Emphasis directly on the beam.

A single tooth notch is used for a roof with a large angle of inclination, where the angle between the mauerlat and the rafter leg is more than 35º. To do this, you will need to cut a tooth with a spike in the rafter leg, and create a nest under it in the Mauerlat. The use of a spike avoids lateral displacement of the rafters. The double tooth notch is used when installing more gently sloping roofs. The latter method is used extremely rarely.

More and more lately wooden mount for rafters is replaced by metal, because it allows not only to get more reliable, but also to significantly reduce the work on its installation. Therefore, metal rafter bolts, brackets, plates, clamps, hinges and various corners are used as additional fasteners.

The most used method of rigid connection is driving nails from the sides at an angle into the mauerlat. Thus, internal crossing takes place within it. Further, for the final fixation of the connection, the third nail is driven vertically. Another way to prevent transverse displacement of the rafter leg is to fix it on the sides with metal corners.

The scheme for movable fastening of the rafters in the lower part is used for houses built from logs or timber. Since during operation the truss system is in motion due to changes in its physical properties, i.e. the building shrinks.

The rigid fastening scheme in this case is unacceptable, since such movements can lead to the destruction of the wall. This means that the attachment points need to provide mobility. In such cases, special swivel joints, which are called sleds or corners with an oblong hole for fasteners. The sliding interface in this fastener achieves two levels of freedom through the free movement of one of the fastener elements.

Nodal ridge connection

The ridge connection of the truss system can be obtained in three ways: butt, overlap and on the ridge beam.

Butt. The upper part of the rafter leg must be cut at an angle equal to the slope of the roof. The opposite leg is also adjusted to the appropriate angle, but with an inclination to the other side. Further, they are interconnected at the top point with the help of a nail, which must be driven into the end of the rafters with the capture of the opposite end. In addition to nails, special plates are used for a more durable connection of joints. Both a 30 mm wooden board and a double-sided metal fixing plate can act as such fasteners. For its installation, bolts or nails are used.

The next two methods will be similar to the first, but have a slight difference. When fastening with an overlap, the upper parts of the rafter leg will be interconnected by their sides. The latter option is carried out by connecting each rafter directly to the ridge beam. In this case, threaded studs with washers and bolts are used as fasteners.

If trusses are used to stiffen the rafter system, then to ensure good resistance to wind loads, it will be necessary to install the required number of diagonal ligaments. The presence of a brace and a brace (rafter leg) in the supporting structure helps the gables of the house to be more stable. The brace is installed by resting the upper part in, and with the lower part it rests against the main floor beam. The strut helps to reduce the load on the rafters in the center. Its installation is carried out at an angle of 45º. Diagonal connections are fixed using clamps, corners, plates.

Types and features of metal fasteners for rafters

If earlier craftsmen used wooden elements as such fasteners (bars, slips, dowels, metal staples, wooden pins, wedges), now such methods are inferior to more modern species. The construction market is big the lineup metal fasteners, which are now much stronger and make the process much easier. The manufacturing technology of these elements uses metal, the thickness of which varies from 1.5 ... 3.0 mm, which allows the product to be more resistant to loads compared to any other material. In addition, rafter fasteners are available in any size and allow you to carry out the technological process with great accuracy.

The metal fasteners of the rafters, which can be perforated and nailed, include:

• perforated mounting tape;
• corners;
• plates;
• beam support;
• beam support;
• wire tie;
• self-tapping screws;
• bolts with nuts;
• corners of the KR;
• brackets WB;
• fasteners LK.

The use of perforated products allows strong enough with all parts of the system and provide good rigidity and strength at any angle. They are characterized by the presence of many holes for bolts, screws and self-tapping screws, with the help of which the attachment to the tree is carried out. The size of the product is adjusted by trimming to the desired length and width.

Also fasteners can be nailed. However, the use of this type is possible only in the factory by cutting, which bends the cone-shaped part. This operation is carried out by special machines under pressure.

KR corners have a large number of modified types, reducing the risk of breakage bolted connection with natural settlement of the structure. Fastening is carried out without the use of special equipment using screws and nails.

WB brackets are used to mount the console carrier beam on device wooden floors in houses made of rounded logs or timber. At the same time, the tie-in on the rafter leg is not made, which does not weaken its bearing capacity. The connection is carried out using anchor bolts, nails or screws.

LK rafter fasteners are applicable where it is required to connect rafters and beams. It has the same advantages as WB fasteners, but the process is carried out only with screws or nails. Used in the construction of wooden houses.

Fasteners in the rafter system play a huge role. It depends on him the strength and duration of operation of the entire roofing pie. Therefore, the choice of type and method of attachment should be treated with great attention.

In order for the constructed building to serve for more than one year, it needs both a reliable foundation and a strong roof system that resists the vicissitudes of the weather. The roof must withstand heavy loads with dignity: heavy snowfalls, sharp gusts of wind, torrential downpours. The roof truss system is best suited for this.

Roof trusses and its types

The truss system is the basis of the roof, which focuses on the load-bearing elements of the structure and also serves as a frame for various types of roofing materials: insulation, waterproofing, various coatings.

The dimensions and design of the rafters depend on:

• purchased material;
• the size of the building;
• dimensions of the house;
• building material for rafters;
• individual preferences of the customer;
• roof loads relevant for a particular region.

The rafter system has:

• crate - bars, in a perpendicular direction, fit on the rafter legs;
• screeds that perceive tensile forces;
• wooden racks, located in a vertical position;
• mauerlat - a bar, the installation of which is carried out along the wall, the rafters focus on it;
• rafter legs are a kind of wooden beams that take on the main load of the roof.

Each of these factors is very important, because it is necessary to understand what type of truss system will be best suited for a particular situation.

When it comes to low-rise buildings, wooden structures are the most common. In many cases, three types of truss trusses are used: hanging rafters, layered rafters and a mixed rafter system.

Characteristics of hanging rafters

Hanging rafters are the most elementary type of truss systems, their characteristics:

If the roof of the house complex design, types of rafters can be alternated. For example, in the presence of supports or the middle main wall, they install layered rafters, and in the absence of such elements, hanging rafters.

Features of layered rafters

For a layered rafter system, the house must be additionally equipped bearing wall located in the middle. There are layered rafters according to the following features:

Design combined system the most complex, since it includes parts of two other types of rafters - hanging and layered. It is applied for mansard roof. The walls of the rooms, which are located on the second floor, form vertical supports, these supports are also intermediate racks for truss beams.

Part of the rafters that connect one end of the uprights functions as a crossbar for the slopes located on the side, and for the upper part of the structure they are a puff.

At the same time, the horizontal bars perform the following functions: for the upper slopes - a Mauerlat, for the side ones - a ridge beam. To increase the strength of the roof, struts are mounted that connect the side slopes and vertical racks.

The combined sling system is the most complex and time-consuming to manufacture, but these shortcomings are fully compensated by an increase in the bearing qualities of the roof in the absence of extra supports, especially when there is a need to cover significant spans in the building.

You can increase the bearing qualities of the roof using a mixed truss system

Rafter trusses for various types of roofs

During the construction of a certain building, roof systems of one kind or another are necessarily used, and the type of roof will completely depend on the design of the future structure.

Rafter truss for a gable roof

A gable roof is a common roof construction for residential buildings that have no more than three floors. Preference is given to this design because specifications inclined form of the truss system, as well as due to the fact that installation work is carried out easily and simply.

The truss system of a gable roof includes two rectangular inclined planes. The upper part of the building from the front side resembles a triangle. The main components of a gable roof are the Mauerlat and rafter legs. In order to properly distribute the load along the rafters and walls, struts, crossbars and racks are mounted, thanks to which you can create a durable, rigid, elementary and light scheme installation of structures for a gable roof.

A gable roof is considered the simplest roof system; it is used for residential buildings no more than three floors.

On top of the rafters, you can mount a sparse crate or a solid one, and then attach a bituminous coating, tiles or some other type of material to it. The rafters and sheathing itself are usually made of beams or boards, which are fastened with nails, bolts or metal fittings. metal profiles can be used as rafters, due to which significant spans overlap. There is no need to use extra racks and struts.

The device of the truss system for a gable roof allows you to evenly distribute all the existing load along the perimeter of the building. The lower ends of the system focus on the Mauerlat. They are fixed with metal fasteners or staples. By the angle of inclination of the bars for the rafters, you can determine at what angle the roof slopes will be inclined.

The truss system for a gable roof allows you to evenly distribute the load from the roof along the perimeter of the building

Rafter system for a hip roof

When arranging a system for a hip roof, you will need to install different types of rafters:

• conjurers (shortened);
• side;
• hip main;
• sloping (diagonal elements that form a slope in the shape of a triangle).

The rafter legs located on the side are made of board, and they are mounted identically to the details of a traditional pitched roof with a layered or hanging structure. Hip main rafters are layered parts. For sprigs, boards or bars are used, which are attached not only to the Mauerlat, but also to the diagonal beams.

To install this type of construction, the angle of inclination is accurately calculated, as well as the cross section of the sloping beams. The dimensions of the parts also depend on the length of the span.

To hip roof not deformed from a heavy load, you should accurately calculate the angle of inclination of the diagonal beams for the rafters

Observe symmetry when installing diagonal beams for rafters, otherwise the roof is deformed from a significant load.

Rafter system for sloping roofs

A broken roof is a structure with rafters, which consist of several individual elements. However, they should be located under different angles relative to the horizon. And since the bottom rafter part is almost vertical attic room building receives additional area which makes it suitable for residential use. The device of this type of roof is carried out during the construction of a four- or gable rafter structure.

count four-slope system rafters are needed by professionals, but a gable broken roof can be made independently, since its installation is very simple. To do this, it is necessary to install a support frame, which should consist of runs, as well as racks. Horizontal parts are fixed with hanging rafters. But to the Mauerlat, the supports of the sloping roof are fixed with shortened legs of the rafters.

The assembly of rafters for a broken gable roof can also be performed by non-professionals, since the installation of such a roof is very simple.

"Cuckoo" in the roof truss

The so-called cuckoo on the roof is a small ledge that is located on the attic floor. Here is a window for better lighting attic room. The installation of the "cuckoo" is carried out carefully, while controlling the parameters of the entire structure: the depth of the cut, the angle of inclination and other factors. However, before that, the necessary measurements are made.

The first stage of work begins with the installation of a power plate (a beam with a section of 10x10 cm, which is needed to support the lines). The truss system acts as a skeleton for the roofing material. To stiffen the structure, spacers are used, which are mounted between the two legs of the rafters.

After the installation of the truss truss is completed, a sheathing is laid, the type of which depends on the roof covering purchased. The installation of the crate is done continuously or with a certain step. Boards, OSB and plywood sheets are usually used for it. In addition, the installation of roofing material must be identical throughout the entire roof.

The main difficulty in installing such a rafter system is the location of the internal corners. In these places, snow can accumulate, which means that the load will increase, which is why a continuous crate is made.

"Cuckoo" on the roof is called a small ledge on the attic floor, under which there is an additional window

Chalet roof truss truss

A feature of a device of this design is the removal of visors, as well as overhangs outside the house. In addition, there must be rafters and beams for the roof, which extend up to three meters on the sides of the building. Each of these elements is fixed with a bracket to the wall of the building in the lower part. Next, tie the edges of the beams. They serve as a support for covering the roof of the building.

But creating large overhangs, it is necessary to carry out installation reinforced belt in parallel with the installation of studs for Mauerlat. It is necessary to make anchors that help fix the consoles. In this case, the rafters will be perfectly fixed with anchors and, in addition, tie-ins.

To carry out the side cornices, a ridge beam is made, after which beams are taken out at the Mauerlat level, which must be identical to the length of the ridge. The truss is based on these structural details, and in the future - building material for the roof.

When designing a building, the angle of the roof-chalet is calculated based on the characteristics of the local climate and other factors. With a slope angle of about 45 °, the load from snow is not taken into account, since with this option it will not linger on the roof. At the same time, the sloping roof will withstand the load from the snow, but it is necessary to install a reinforced roof truss. Before installing the roof-chalet, a building project is prepared, because the originality of the roof itself, as well as long cornices and its overhangs, oblige this.

The roof in the style of a chalet is characterized by visors, taken out several meters outside the house.

Roof truss designed for soft roofing

Soft roofing is done in various ways, however, there are technological methods for its construction. General characteristics. Initially, you need to prepare. When equipping a roof for a house made of foam concrete or other material, a Mauerlat is first installed, then a cut is made under the ceiling beams in increments of up to one meter in the upper crowns of the building. The distance between the boards is calculated based on the type of rafter structure.

1. Mount individual parts of the rafter system. To completely eliminate the risk, the boards of the rafter legs on the ground are attached with screws. After creating a truss truss, it is raised to the top of the building.
2. All elements of the rafters are fixed with ceiling overlap, internal boards, jibs, and also crossbars. Further, this basis for the roof will become a single whole structure.
3. The next stage is the crate, which is under soft roof installed with little or no gaps. Gaps of no more than 1 cm are allowed. Quite often, leveling plywood is installed on top of the boards. Her sheets are laid according to the method brickwork. The resulting joints do not align with the gaps between the plywood and the board.

If the length of the boards of the crates is not enough, then the joints of the parts must be located in different places. In this way, areas that have been weakened can be correctly distributed.

Self-manufacturing of the truss system

Before the installation of the truss system begins, the Mauerlat must be fixed to the longitudinal walls with anchors. Next, you need to decide on the desired section of the legs for the rafters, depending on the distance and their length. If there is a need to increase the length of the rafters, then connect them with various fasteners.

When using different insulation, you need to choose the ideal distance between the elements of the rafters in order to reduce the number of thermal insulation scraps.

Installation of the truss system must be carried out in the following order:

1. A template is made according to which the farm is assembled. 2 boards are taken, corresponding to the length of the rafters, and connected to each other from only one edge with a nail.

   A rafter template called "scissors" will help you quickly assemble the entire roof truss system

2. You get a design called "scissors". Its free edges are placed on supports at the points of contact of the rafter legs. The result should be the final angle, that is, the angle at which the roof slope will be tilted. It is fixed with several long nails and transverse boards.
3. A second template is made, thanks to which the cuts on the rafters are installed. It is made from plywood.
4. Special mounting cuts are cut out on the rafters (a prepared template is used for this purpose) and connected at an angle of inclination of the slope. You should get a triangle that rises to the roof along the stairs. Next, it must be attached to the Mauerlat.
5. Initially, two side gable rafters are mounted. Their correct installation in the vertical and horizontal plane occurs due to temporary struts attached to the rafters.

   For correct installation of the entire rafter system, the first pair of rafters is installed on the roof

6. A cord is stretched between these tops of the rafters. It will indicate the future skate and the level of other rafters located in the gap.
7. Raise and mount the remaining rafters at the initially calculated distance, which should be at least 60 cm from each other.
8. If a bulky construction of rafters is provided, then it is additionally strengthened with struts, supports, and so on.

   The bulky construction of the rafters is additionally reinforced with struts and supports.

9. On special supports, a ridge beam is installed, to which not only short, but also diagonal and intermediate elements of the rafters are attached.

   Proper fastening of the ridge beam ensures the reliability of the entire rafter system

Typical nodes of a standard truss system

The structural strength of the rafters depends on the ideally selected section of the boards, as well as on High Quality truss knots. The connection of parts for the roof structure is done in accordance with established rules.

The main typical nodes in the truss system:

• supporting knot of rafters on the Mauerlat;
• ridge;
• a node for combining the upper puffs and the entire truss system;
• fixing the strut, rack, as well as rafters and beams.

After the design of the rafter system has been chosen, it is necessary to draw up a plan in which to select all the nodes. In each design, they are made differently, as it depends on different nuances: type of roof, its size, angle of inclination.

Rafter from profile pipe- this is a metal structure that is assembled using lattice rods. The very production of such farms is a very time-consuming process, but also more economical. For the manufacture of rafters used paired material, and gussets are connecting elements. The construction of rafters from profile pipes is assembled on the ground, while riveting or welding is used.

Thanks to such systems, any spans are blocked, but it is necessary to make the correct calculation. Provided that all welding work will be done with high quality, in the future it remains only to transfer the structural elements to the top of the building and assemble them. Bearing rafters from a profile pipe have many advantages, such as:

Crossbar in the truss system

Rigel is a fairly broad concept, but in the case of roofs it has a certain meaning. The crossbar is a horizontal bar that connects the rafters. Such an element does not allow the roof to "burst". It is made of wood, reinforced concrete, and also metal - it all depends on the type of structure. And the crossbar serves to distribute the load exerted by the truss system.

It can be fixed in various places between the legs of the lines. There is a direct pattern here - if the crossbar is fixed higher, then the timber for its installation must be selected with a large cross section.

There are many ways to fix the crossbar to the truss system:

• bolts;
• nuts;
• studs with washers;
• special fasteners;
• nails;
• mixed fasteners when applied in parallel different types fasteners.

Mounting exists with a tie-in or overhead. In general, the crossbar is a design unit, as, indeed, the entire roof sling system.

The crossbar in the truss system is designed to reinforce the roof structure

Rafter system fastening

To ensure the reliability of the rafter system, it is necessary to initially find out how they are fastened to the supporting roof and the ridge. If fastening is done to prevent deformation of the roof during shrinkage of the house, then the rafters are fixed on top with a hinged plate or a nut with a bolt, and from below - with a sliding support.

Hanging rafters need a tighter and more reliable fastening in the ridge, so in this case you can apply:

• overhead metal or wooden plates;
• cutting method;
• connection with long nails.

In the layered system, the rafter legs are not connected to each other, since they are attached to the ridge run.

The rafters are fastened to the Mauerlat by cutting down, which is done in the rafter leg. Thanks to this method of fastening, the support of the roof will not be weakened. Cutting is also done when installing rafters on floor beams. In this case, the cut is also made in the support beam.

Video: how to make rafters with your own hands

Thus, a perfectly matched system of rafters and their design characteristics will help create the basis for reliable roofing for your home.

At the stage of building a house, special attention should be paid to the roof. The reliability of the entire structure will largely depend on how reliably, correctly and efficiently it will be done. One of important details roofing is a truss system that holds finishing material, insulation, waterproofing and other elements. For gable roofs of houses, hanging rafters are often used, the design and components of which, as well as installation, are described in this material.

Rafters are the main load-bearing element of a pitched roof, which takes on the main load experienced by this structure. The rafter system is of two types - hanging or layered. One has to choose between them, based on whether there are internal walls in a structure under construction, which can serve as a support for parts of the roof. System hanging rafters is used if there are no such walls, and here only external walls buildings. That is, these rafters do not have a central support as such and rest on the wall on one side, and on the opposite rafter on the other. The fastening of individual elements is carried out using slotted spikes, nails, anchors or metal plates.

Hanging rafters are usually used to cover spans with a width of 7-10 m. The scope of application can be different - such a system is used for the construction of roofs in warehouses, industrial buildings, residential buildings.

On a note! The maximum distance between the walls, which allows the use of a hanging rafter system, is 14 m.

Despite the fact that such rafters are installed at a slope, they do not act on the walls like spacers - they transfer only vertical loads. This can be achieved through the use of stretch marks made of timber, located at the base of the roof.

On a note! The tightening between the legs of the rafters is located the higher, the greater the load it experiences.

Rafter elements are made of timber, boards or logs, metal. Mandatory before starting installation work material must be treated with special protective compounds which will provide the tree with a long service life. They will protect it from fungus, mold. If the material is treated with fire-fighting compounds, then the house will gain additional protection from fires.

What does the hanging rafter system consist of?

A system of this type has several components. And it is necessary to get acquainted with them in order to understand the purpose of each of them and not to get confused in concepts.

Table. The constituent elements of the system.

Element	Description
	This is the basis of the system. It is thanks to them that it turns out to form the shape of the roof, slopes. They are created from a bar (or board) with a section of 50x150, 100x150 mm and are placed in increments of about 60-120 cm. The dimensions and pitch chosen will directly depend on the parameters of the roof, its design features, calculated load.
	The place where two roof slopes are connected. Usually there is an additional ridge beam.
	With the help of these elements, representing beams horizontally located between the rafters, the rafter legs are tightened and strengthened. Due to the puffs, the load experienced by the rafter legs is compensated.
	A kind of puff, which is located near the roof ridge. It is made of a very durable timber, as it experiences a colossal level of load.
	A beam, which is installed on the upper part of the load-bearing walls, rafters rest on it. It helps to distribute the weight of the entire roof along the perimeter of the building, which makes it possible for the foundation and walls to experience the load evenly. For manufacturing, a bar with a section of 100x100 or 150x150 mm is used. Interestingly, it may not always be used - some types of roofs are equipped without it.
	An element that is installed under the roof ridge and is designed to support a long draw.
	These structural details are used for buildings that have too large spans between load bearing walls. They are necessary to support the rafters, providing them with a minimum bending load, that is, they will not allow them to bend and sag.

Bar prices

Types of structures

There are five main types that can be used in construction roof structures of a similar kind, which can be obtained on the basis of hanging rafters. They differ in having some structural elements, configuration, etc.

The simplest option is triangular articulated arch. Its shape is triangular, the puff here is under tensile load, and the rafters are under bending. Such a scheme is used only if the height of the ridge is at least 1/6 of the entire span between the walls, otherwise it will not function correctly. Quite often used in the construction of attics. In this case, two rafters are joined and connected to each other in the ridge part. At the bottom, the triangle can be connected with a long puff. The system can only be used if the span between the walls is no more than 6 m.

Slightly different from the above system - articulated arch with headstock. In this case, the design has a support in the form of a headstock installed under the ridge. Due to the tightening, it works in tension. The headstock can be made of either metal or wood. The system is used if the spans between the walls are 6 meters or more. The headstock will not allow the puff to sag - it acts as a kind of suspension and allows you to adjust the degree of deflection of the horizontal part.

Articulated arch with puff that is raised, is usually used when planning the construction of attics and spacious attic spaces - that is, where the ceiling height is important. In this case, puffs will be installed at the top of the rafters. And the higher the puff is located, the greater the tensile force it perceives.

If the support is a fixed hinge element, then the structure will be called arch with crossbar. Here the roof is attached to the Mauerlat by forming a tooth on the rafters. The bolt itself resembles a small puff, but in this case it works not in tension, but in compression. Rafter legs are fixed quite rigidly.

Arch with struts and headstock resembles an arch system with a suspension. Here, during the installation of the rafters, struts are used, which ensure that the structure is relieved of excess stress. The option is suitable for closing spans with a width of 9-14 m.

On a note! Any scheme for the design of hanging rafters involves accurate calculations, which will clarify all external and internal loads.

The rafter system is quite difficult to install, sometimes its parts are assembled directly on the ground, and then rise to the roof. But also rafters can be mounted right on the spot. In general, a roof with hanging rafters is the simplest option, therefore it is often made by novice builders or on their own.

Perforated plates used for attaching rafters

Prices for various types of fasteners for rafters

Fasteners for rafters

Ways of fastening rafters

These structural details can be fixed in two ways.

1. Bolt and clamp, where in this case the end part of the rafter is cut off, and she herself is placed on the beam in the place where the notch is made. The fastening of individual elements is carried out with the help of bolts. They are connected so that the attachment point is perpendicular to the upper part of the rafter. Sometimes clamp systems are used for connection.
2. double tooth. The method is applicable if the slope of the roof slope relative to the horizontal is less than or equal to 35 degrees. In this case, two stops are made on the beam, a special hole is made in the rafter leg, and a spike is cut out at the place of the extreme stop on the beam. In size, these elements must correspond to each other.

System design

To correctly create a system layout, it is important to consider:

• rafter installation step;
• load on the structure and structure;
• section of rafters;
• material that will be used to create the roof;
• construction type;
• roof pitch angles
• the dimensions of the building as a whole;
• climatic conditions of the region.

The more accurately the calculation is made and the more correctly the rafter system is designed, the stronger and more reliable the whole structure will turn out. For convenience, you can use the existing online calculators, which is important for those who are not friends with the exact sciences, or for beginners.

Video - Roof truss system, what you need to know for proper design

Installation rules

Installation of hanging rafters must be carried out in compliance with certain rules. Only in this case it will be possible to make a correct and stable design. The work rules are as follows:

Installation of hanging rafters

For the construction of the truss system, certain tools and materials may be required. The list below is quite approximate, but can be used as a basis during preparation for the start of work.

Tools for creating a rafter system:

• hammer;
• axe;
• jigsaw or hacksaw;
• building level, twine, tape measure;
• thread with a load (plumb line);
• pencil, ruler.

Prices for popular models of jigsaws

As necessary materials you can list directly the beams and boards for rafters, self-tapping screws and nails, anchor bolts, waterproofing material, antiseptic compounds for wood processing.

Sigma-Extra - outdoor work, antiseptic for wood

Consider the installation process of the truss system step by step.

Step 1. Whole wood material it is treated with antiseptic agents that prevent the development of decay processes, the occurrence of fungus and mold. Prior to installation, the material is well dried.

Step 2 Construction material delivered to the top of the building.

Step 3 A mauerlat is nailed along the perimeter of the load-bearing wall, consisting of two boards of such a width that they can cover the entire upper part of the wall with themselves. Between the Mauerlat and the wall, it is recommended to lay a layer of waterproofing material (for example, roofing material). This will seal the joint, protect the material from moisture and reduce drafts in the future.

Step 4 Next, beams are created from the timber, which will be attached to each pair of rafters in the lower part. They are attached to the Mauerlat and connect two load-bearing walls together. You can temporarily move along them during the work, and boards that are used to create rafters are also folded on them.

Step 5 To form the top of the roof, a ridge beam is cut out. It must be one piece long. future roof to the other and be parallel to the long load-bearing walls.

Step 6 The required roof height is determined - the level at which the ridge beam will be attached. The angle of inclination of the slope is recommended to be done within 25-45 degrees. You can find out the angle of the roof and the length of the rafters using the Pythagorean theorem. To do this, you need to measure the distance from the ridge, the height of the roof and the distance to the outer wall.

Step 7 The ridge board is installed at the place of the future docking of two rafter legs.

Step 8 From the prepared lumber, future rafters of the desired length are measured and cut. They will be attached with the selected pitch to the ridge board and Mauerlat.

Step 9 To make it possible to attach the rafters to other elements, special triangular cutouts are made. To do this, the board is installed so that one side lies on the ridge board, and the other on the Mauerlat. The cut mark is applied. Next, the marked sections are cut.

Step 10 The second rafter is prepared in the same way. Now they should be docked with each other. To do this, the boards are moved as close as possible to each other, markings are applied indicating the place of the cut. The cut is made and the boards can be joined.

Step 11 The rafters are attached to the Mauerlat with metal corners and self-tapping screws. With the help of them, the boards are also fixed on the roof ridge.

Step 12 Two rafters are interconnected using metal plates and self-tapping screws. Thus, the first two structures are installed, which will be located at the edges of the roof.

Step 13 In order to make it easier to evenly install other rafters, a rope is stretched strictly horizontally between the extreme structures.

The process of installing rafters

Step 15 If necessary, the rafters can be reinforced with puffs that are attached to two joining rafters.

Video - Installation of the truss system

Video - Installation of rafters

Video - Using a crossbar (screed) for rafters as an interior element

Hanging rafters are considered a fairly simple design compared to other types of truss systems. But there should be no rush during their installation. It is important to remember that at the slightest skew, all work will go down the drain, so you need to work carefully and carefully.