How to make a dual roof: step by step instructions in photos and videos. How to put rafters on the roofs of different designs

Rafters serve as the basis for the entire roofing structure, and their installation is one of the most crucial tasks in the construction of a house. The skeleton of the future roof can be made and installed independently, observing the technological features of the roofs of different configurations. We give the basic rules for the design, calculation and selection of the rafter system, and also describe in stages the installation process of the roof skeleton.

  Rafter system: rules of calculation and development

The rafter system is a supporting structure that can resist gusts of wind, take on all external loads and evenly distribute them to the internal supports of the house.

When calculating the truss construction take into account the following factors:

1. Roof angle:
   • 2.5-10% - flat roof;
   • more than 10% - pitched roof.
2. Roof loads:
   • permanent - the total weight of all elements of the "roofing pie";
   • temporary - wind pressure, snow severity, weight of people who carry out repair work on the roof;
   • force majeure, for example, seismic.

The amount of snow loads is calculated based on the climate characteristics of the region according to the formula: S = Sg * mwhere Sg  - snow weight per 1 m2, m  -the calculated coefficient (depends on the slope of the roof). Determination of wind load is based on the following indicators: type of terrain, standards of wind load of the region, building height.

The coefficients, the necessary standards and calculation formulas contained in the engineering and construction reference books

When developing a truss system, it is necessary to calculate the parameters of all components of the structure.

  Elements of truss construction

The rafter system includes many components that perform a specific function:

  Materials for the manufacture of rafters

Rafters are most often made from coniferous trees (spruce, larch or pine). For the arrangement of the roof is used well-dried wood with a moisture level of up to 25%.

The wooden structure has one major drawback - over time, the rafters can be deformed, therefore elements of metal are added to the carrier system.

On the one hand, the metal adds rigidity to the truss structure, but on the other hand, it reduces the lifetime of the wooden parts. Condensate accumulates on metal platforms and supports, which leads to decay and deterioration of wood.

Council When installing the truss system of metal and wood, you need to take care that the materials do not touch each other. You can use moisture protection or apply film insulation

In industrial construction, metal rafters are used, made of rolled steel (I-beams, brands, corners, channels, etc.). This design is more compact than wood, but it retains heat worse and therefore requires additional thermal insulation.

  Choice of truss system: hanging and mounted structures

There are two types of truss structures: hanging (spacers) and mounted. The choice of system is determined by the type of roof, overlap material and the natural conditions of the region.

Hanging rafters  they rest solely on the external walls of the house, intermediate supports are not involved. Hanging rafter legs perform compression and bending work. The design creates a horizontal arching force transmitted to the walls. With the help of wooden and metal puffs you can reduce this load. Puffs are mounted at the base of the rafters.

A hanging truss system is often used to create an attic or in situations where roof spans are 8–12 m and no additional supports are provided.

Rafter rafters  They are mounted in houses with an intermediate column support or an additional supporting wall. The lower edges of the rafters are fixed on the outer walls, and their middle parts - on the inner wall or bearing column.

Installation of a single roofing system over several spans should include expansion and napsled trusses. In places with intermediate supports mounted naslon rafters, and where they are not - hanging.

  Features of arrangement of rafters on different roofs

  Gable roof

The gable roof, according to building codes, has an angle of inclination of up to 90 °. The choice of slope is largely determined by the weather conditions of the area. In areas where heavy rainfall prevails, it is better to install steep slopes, and where strong winds prevail there are gentle roofs in order to minimize the pressure on the structure.

A common variant of a gable roof is a design with a tilt angle of 35-45 °. Experts call such parameters the “golden mean” of the consumption of building materials and load distribution along the perimeter of the building. However, in this case, the attic space will be cold and it will not be possible to equip a living room here.

For the gable roof is applied naslonnaya and hanging truss system.

  Hipped roof

All roof slopes have the same area and the same angle of inclination. Ridge runner is not here, and the rafters are connected at one point, so the installation of this design is quite complicated.

Tent roof is advisable to install when two conditions are met:

• the base of the building is square;
• in the center of the structure there is a bearing support or wall, on which it will be possible to fix the stand supporting the joint of the rafter legs.

It is possible to create a hip roof without a rack, but at the same time, the construction should be strengthened with additional modules - strut puffs.

  Hip roof

The traditional design of the hip roof assumes the presence of slanting rafters (diagonal), directed to the corners of the building. The slope of the slope of such a roof does not exceed 40 °. Diagonal runs are usually done with amplification, since it is they that account for a substantial part of the load. They make such elements from a double board and a strong bar.

The joining points of the elements are necessarily supported by a stand that increases the reliability of the structure. The support is located at a distance of ¼ the length of the large rafters from the ridge. In place of the gable roof gables, shortened rafters are installed.

The truss structure of the four-sided roof may include very long diagonal elements (more than 7 m). In this case, it is necessary to mount a vertical stand under the rafters, which will rest on the floor beam. A sprengel can be used as a support - the beam is located in the corner of the roof and is fixed on adjacent walls. Sprengelnuyu farm amplify struts.

  Broken roof

Broken roofs are usually created for the arrangement of a larger attic. Installation of rafters in this version of the roof can be divided into three stages:

1. Mounting the U-shaped design - supports for the girders that hold the rafter legs. The basis of the design - beams of overlap.
2. At least 3 runs are installed: two elements pass through the corners of the U-shaped frame, and one (ridge run) is mounted in the center of the attic floor.
3. Installation of truss legs.

  Duplex roof: installing rafters do it yourself

The calculation of the angle of inclination and loads

The calculation of the dual-slope roof can, of course, be carried out independently, but still it is better to entrust it to the professionals in order to eliminate errors and be confident in the reliability of the construction.

When choosing the angle of inclination, one should take into account that:

• the angle of 5-15 ° is not suitable for all roofing materials, therefore, first choose the type of coating, and then make the calculation of the truss system;
• when the angle of inclination is more than 45 ° - material costs for the purchase of components of the “roofing pie” increase.

The load limits of snow exposure range from 80 to 320 kg / m2. The design factor for roofs with a slope of less than 25 ° is 1, for roofs with a slope from 25 ° to 60 ° - 0.7. This means that if there is 140 kg of snow cover per 1 m2, the load on the roof with a slope at an angle of 40 ° will be: 140 * 0.7 = 98 kg / m2.

To calculate the wind load, the coefficient of aerodynamic influence and fluctuations in wind pressure are taken. The value of the constant load is determined by summing the weight of all the components of the “roofing pie” per m2 (on average 40-50 kg / m2).

Based on the results, we find out the total load on the roof and determine the number of rafter legs, their size and cross-section.

  Installation of mauerlat and rafters

The installation of the rafters with their own hands begins with the installation of a mauerlat, which is fixed with anchor bolts to the longitudinal walls.

Further construction of the structure is performed in the following sequence:

Installation of rafters: video

Ways of connecting elements of truss construction: video

As you know, the roof system is the main supporting structure of the roof. It is she who “holds” on herself the entire load of the roofing “pie”, as well as all the loads of snow and wind. That is why its construction must be treated "responsibly." And how to install such a system? How is the installation of rafters on the roof? What nuances should be considered here? This and other issues related to the truss system will be discussed in the article.

General concepts

Installation of rafters is one of the important stages of the construction of any roof. Most often, this work is entrusted to professionals, as it is quite complex. But, if there is some experience in construction and carpentry, then it can be done with your own hands. But before proceeding to the installation of rafters, you should familiarize yourself with the design of the roof.

This system includes the following components:

1. Chutes. Their number depends on the type of roof. The most common variant is the dual-slope. It is this main part of the roof that is supported by the rafters that you will be laying.
2. Along the perimeter of all the walls, the top is produced. This element can not be used if the house is built of wooden bars. The lower end of the rafters is attached to the mauerlat. This element is necessary so that the weight of the entire system is evenly distributed on the walls.
3. Fad. This is the top of the roof. Here the slopes and rafters converge. This element is present in any type of roof, except odnoskatnogo option.
4. Endova. It may not be included in all designs. Endova is present in those cases when the ramps, and accordingly the rafters, form the incoming angle.
5. Overhang or cornice. This element is designed to ensure that precipitations flowing from the roof do not damage the walls and the foundation. The overhang can be a direct continuation of the rafters or be their separate component. The eaves can retreat from the walls at any distance you prefer, but it should not be less than thirty centimeters.
6. Roof. This part will directly protect your building from external influences. The roof may have the appearance of a kind of "cake". If in a, then you have to install insulation and other layers. If there is no attic, it is enough to lay the roofing material and waterproofing.

The rafter system is the backbone of the entire roof. It will carry all the loads from the roofing “pie” and other components. Therefore, the installation technology rafters must be strictly observed. Proper installation will guarantee a long service life of the entire building.


Material for rafters

During the construction of the roof is important to responsibly approach each stage. Installing rafters is “serious.” But, if these elements are of poor quality, then little will depend on proper installation. Rafters can quickly fail and then you can not avoid serious repairs.

Before proceeding with the installation by hand, you should select the material for these basic elements of the entire roof system. And which option can I use? Here, experts will offer the following:




You can install wood rafters with your own hands, using only the usual set of carpenters. Most commonly used parallel bars. In some cases, you can apply and boards. The most important thing is that the material is of high quality. Do not use boards or parallel bars for a long time.


Training

Before you put the rafters, you should go through the preparatory stage. First of all, you should make a scheme. Without accurate drawing it is impossible to properly install the rafters. In drawing up the scheme should take into account the following points:

1. Which truss system will be used. There are two options - it is naked and. In each case, the installation of rafters made by its own rules. This must be taken into account.
2. To determine the angle of the slope. It takes into account various parameters. First, the natural conditions in your area. The smaller the angle of inclination, the more snow accumulates. This reduces the wind load. With a large tilt angle, the opposite is true. Secondly, recommendations from the manufacturer of the roofing material should be taken into account.
3. Load. Before you make a diagram, you should decide on what forces will affect the entire structure. Based on this, all parameters of the rafters themselves and the frequency of their installation are calculated. Both variable and constant loads are taken into account. The first include atmospheric effects - this is precipitation and wind. Permanent loads include the weight of all components of the roof, including installed equipment, read more:.
4. Parameters themselves rafters. Here you need to calculate their length and cross section. These values ​​will depend both on the design features of the roof itself, and on the loads it must withstand, see also:.

After drawing up the scheme should prepare all the necessary materials and tools. Particular attention should be paid to the rafters themselves and another component of the truss system. Wood is a capricious material. Therefore, the installation of rafters must begin with their processing of various impregnations.


In addition, you need to carefully examine each board or timber that will be used. If rotting traces or a large number of knots were noticed, then it is better not to use such material for installing rafters. You should also carefully consider the moisture content of the wood. This parameter should not exceed ten percent.

In addition to wood for rafters, you need to prepare other materials and tools. First of all it is necessary to stock up on fixture. The installation of rafters is carried out using mainly nails. But besides this metal brackets, corners and other devices can be used.

If we are talking about tools, then the usual set of carpenters will fit perfectly. The installation of rafters with their own hands is carried out using a saw, ax, planer, drill and other tools. In addition, you should prepare a device for applying the markup.

Ways to join rafters

Wood is amenable to processing. That is why, of course, except for all other advantages, it is chosen during the construction of the roof. Because of the ease of processing, there are many ways to join wooden elements. Before you start installing rafters, you should know how they can be fastened together, build up and connect with other components of the system.

To perform these tasks, you can use the following options:




There are other methods for mounting rafters on the mauerlat. Each specific option has its pros and cons. But besides the mauerlat, the rafters must also be fastened among themselves. This is done at the top of the ridge of the roof.

There are also many ways. Installation can be carried out using bolts, plates, hinges or with the use of a cutter.


We carry out installation

How to install rafters on the roof? What are the nuances and subtleties here? The first thing to remember about security. Laying rafters at high altitude is dangerous. It is best to make scaffolding before installation. But such a thing is very expensive and rarely used. Therefore, the installation of rafters on the roof should be carried out with personal protective equipment - this mounting belt and so on.

In addition, to do everything with your own hands and alone is an almost impossible task. Raise and install rafters alone will be impossible. Wood weighs a lot. In addition, the structures themselves will be quite large. Therefore, without an assistant you can not do.

The technology of installing rafters on the roof is as follows:

When building private houses, the roof is most often made gable. There are reasons for this. The first is that it is reliable. It copes well with wind and snow loads. The second is that it is compatible with any roof covering. The third is relatively inexpensive. The fourth is a simple design that is hard to spoil. Fifth - it looks attractive. All this, and the fact that the double-slope roof is built with no hands on any special knowledge, determines its popularity.

Assembled dual roof with their own hands ready for installation of roofing

Step mounting of a dual roof

As you saw above, there are a lot of truss systems. Accordingly, when assembling each has its own characteristics, but in general the order is the same. It is necessary to say about the general step: pre-drying and wood processing. This stage is required if you bought fresh lumber, and not dried.

The use of raw wood in the construction of the roof of natural moisture will lead to problems: beams will bend, they will dry out, the geometry will change. All this will lead to the emergence of points of tension and with the slightest signs of overload (a lot of snow, strong wind or rain), negative processes will begin. Their elimination is a complex and expensive event. Therefore, either buy dry wood (no more than 20%, ideally 8-12% chamber drying), or buy material for a couple of months, fold it into ventilated piles. After that, treat with necessary impregnations (from fungal damage and to reduce inflammability) and only after that use in the installation of the truss system.

Lumber need to be dried in ventilated piles. To do this, they lay a short pieces of boards. They are put in a meter from the edges and further through the meter. Under the bottom install necessarily pads

On the main stages of assembly, on how to make a dual-slope roof do it yourself in this section.

Mauerlat

The assembly of the truss roof system with the installation of the power plate begins. It must be set horizontally strictly, so before starting the installation, the horizontal position of the wall to which it is attached is carefully checked, if necessary it is leveled with cement mortar. You can continue working after the solution has gained 50% strength.

Depending on the system, it is a timber with a cross section of 150 * 150 mm or a board with dimensions of 50 * 150 mm. It is attached to the top row of masonry walls. If the house is wooden, its role is performed by the upper crown. If the walls are made of lightweight building blocks - foam concrete or aerated concrete and others - their rigidity is not enough to redistribute the load. In this case, a reinforced reinforced concrete belt is made on top of the last row of masonry, into which mortgage fasteners are fastened — wire or studs. A bar or board is then mounted on them.

There are several ways to bond the walls and the mauerlat:

• In the masonry (in the reinforced concrete belt) a smooth rolled wire of large diameter is fastened (the two ends stick up). In the board, then holes are made in the necessary places through which the wire is passed. She then twists and bends.
• Studs are immured in the wall at least 12 mm in diameter. Below them, holes are made in the mauerlate, a bar / board is put in) and they are tightened with nuts with wide washers.
• Align the timber or board on the outer or inner edge of the wall, take a drill with a diameter of 12 mm make holes for anchor bolts. They (of the same diameter of 12 mm) are hammered down to the very cap, then they are tightened with a key.

The distance between the pins (wire) should not be more than 120 cm. A cut-off waterproofing must be laid on the wall (belt) under the power plate. It can be in two layers rolled roofing material or hydroizol, it can be smeared with bitumen mastic.

Installation of rafters

Types of roof systems gable roof, there are more than a dozen. First of all, you need to choose how yours will look. Further, in order to work easier, from thin boards make a template for all zapilov, cuts and other similar details. To do this, you may need to assemble the first form on the roof, and then ready to make templates.

Assembly order depends on the type of truss system. If the rafters are mounted, they are installed gradually, collecting from the elements directly on the roof. In this case, it is convenient if the ceiling beams are laid and, if possible, a rough attic or attic flooring.

In systems with hanging rafters, a farm is assembled on the ground - a ready-made triangle of tightening and rafter legs with all the required struts and racks. The required number of farms is collected immediately. Then they are lifted to the roof, they are placed vertically there and fastened to the power plate.

On the one hand, this is convenient - it is easier to work on the ground, with high assembly speed, the accuracy is high: one farm is not much different from the other, which simplifies the procedure. But raising finished farms can be difficult, especially for large buildings. To make this easier, install two slanted boards, which at one end abut the ground, and the second sticks out slightly above the wall. The farms are brought closer to this “lift”, one set down, tied up with ropes and pulled down over the boards on the roof. In the absence of a winch or a crane, this is the most acceptable method.

Assembling the rafters requires certain knowledge: how and in what order to assemble them, how to mark and make gash. Assembly of one of the schemes with grandma, see the video.

Assembly procedure trussing system

Everything, the gable roof is assembled and assembled and ready for the installation of the roofing material.

The very process of installing rafters raises enough questions, but there are many ways and it is impossible to tell about all. One of them is in the video. The system was large and rose to the roof in parts, and there it was already assembled into a single structure. For large houses it is convenient.

Features of mounting truss system of a wooden house

The difference between wooden houses is that the frame shrinks, and this leads to a change in the geometry of the truss system. If the elements are fixed tightly, the roof may fall apart. Therefore, fixtures are made floating. There are special sliding mounts, which in this case attach the rafters to the upper crown and to the purlins, if there are any (see photo).

In order for the rafter to move freely during shrinkage, its long part is fixed strictly parallel to its edge, and the prop is placed strictly perpendicularly. If necessary, a platform is carved under it. Mark the mount so that the hook is in the lowest position or near it. Attach to the special screws that are included (the usual does not fit). If the assembly is made on a log so that the rafter leg does not slip on it, a semicircular hole is cut in the lower part, on which it will rest.

Such fasteners are sold in any construction market, it is called "slippery." How to mount the slide to the bar, see in the video.

Video on the assembly and installation of roof systems gable roofs

The dual-slope roof is not easy to build with your own hands: there are a lot of subtleties and nuances, there are different ways of fastening and building. To describe in words their business is ungrateful. This is the case when it is better to see. Below we offer a selection of videos that may be useful to you.

Video report on how the dual slope roof is made

The story of the owner of the house about the stages of construction. There are interesting technical issues that may be useful.

Two types of rafter connections: rigid and sliding

Video about the two most problematic types of connections.

How to determine the angle of rafter

Complete video report on the assembly of the truss system

This film takes a little less than an hour, but the message of the process is demonstrated from beginning to end with many details. Roof put on, but when installed on buildings of another type (except wooden houses) there is no difference.

Designing a country house includes not only the calculation of the type and strength of the foundation, the area, height and number of floors of the building, but also the construction of the roof. When developing a project, all factors are taken into account, and the optimal variant of the system of rafters is selected that is able to decorate a building and protect it from cold and rain.

If you decide to build a house yourself, you need to know what the roof system consists of and how to install the rafters on the roof to get the desired result. In our article we will talk about the truss system, the rules for its installation and types of rafters.

Whatever form of roof you choose for your home, there will always be a truss system at the heart of the roof structure. To cover the roof with roofing material, a crate and waterproofing layer are laid on the rafters system.

For the manufacture of the structure, a coniferous tree is used with a special treatment with protective agents and moisture not exceeding 2%.

Note! Wood grade 1 is needed for tightening and hanging trusses. Material 1 and 2 grades buy for rafter legs. Wood grade 3 can only be used for the manufacture of racks and struts.

The durability and strength of the truss system depends on the quality of the material, the reliability of the connections and the correctness of the design calculation. Pay special attention to rafters. Let's take a look at what the rafters are made of so that it is easier to do the assembly and installation of the entire system on the roof.

The rafter consists of the elements:

• rafter legs;
• the struts abutting against the upper part of the building wall (in other words they are called braces);
• the racks supporting rafter legs and located vertically;
• support beams (crossbars) which serve as the basis for all load-bearing elements of the roof and are laid parallel to the base of the building between the rafters;
• in the rafters of the hanging type there are racks that work in tension along the vertical and have a name - headstock;
• for resistance to spacer forces are installed.

These are the basic elements of the rafter, but additional components are used for complex structures of rafter systems. To install rafters on the roof with your own hands you need to prepare materials and tools:

• waterproofing material;
• rafters;
• boards;
• fasteners;
• hammer and ax;
• nail puller, tape measure;
• electric drill with a set of drills;
• chainsaw;
• level and pencil.

When everything is ready, it is time to start building the roof, and therefore installing the rafters on the house.

Installation

Stage # 1. From boards to make a template designed truss truss. Raise two planks to the ceiling and connect their edges at one end between each other with nails. Dissolve the boards to the side and install the free edges on the laid support beam. To fix the angle formed between the boards, nail the cross bar.

Lower the template from the boards onto the support beam and with a pencil mark the trimming angle of the rafter for durable fastening. This method allows you to quickly and easily choose the right angle of cut and installation of rafters.

Note! At this stage of the work can not be in a hurry. The better the template is made, the more reliable and stronger the whole structure will be.

Stage 2. Put the template on the ground and start making rafters. The template must be well bonded so as not to disturb the angle of connection of the rafter legs. When the first truss (farm) is ready, it is lifted onto the building and put on the ground.

Stage 3. On rafters and Mauerlate mark the place of the cut. Chainsaw make a cut for proper installation. Proceed to the assembly of the next truss truss.

Stage 4. The first two prefabricated trusses of the truss system should be installed on the mauerlat along the edges of the house. To determine the required level between them, pull the cord.

Note! The rafters installed along the edge of the power plate are fixed with supports on both sides. The installation of the truss should be strictly perpendicular to the base of the slab.

Stage number 5.  The level is set, all fasteners are carefully checked and it's time to start assembling the remaining rafters. The number of farms is determined on the basis of the total length of the system and the step between trusses of no more than 0.8 m. It is easier to assemble the structure on beams.

Note! To avoid shifting the rafters, it is best to score two boards between them.

Stage # 6. The time has come to do the installation and mounting of supports and transverse strips. In addition, it is desirable to resolve issues with waterproofing, vapor barrier and thermal insulation of the entire roofing system. For installation of roofing material crate is installed. The frequency of fastening of the elements of the batten depends on the selected roofing material.

The type of roof depends on which angle of slope of the roof is chosen. For a flat roof, the slope angle does not exceed 10%, and for a sloping structure, the slope angle is always greater than 10%. Pitched roofs come in various designs:

1. Based on two sides of a building of different levels, the roofs are called leaning.
2. Based on the sides of the same level of construction are called gable.
3. Four-pitched roofs are distinguished by triangular slopes. When the ramp does not reach the eaves, the roof is called a half-hinged.
4. Converging to one point the tops of the four triangular slopes form a hipped roof.
5. The mansard truss system is also called a sloping gable, different in that it consists of rectangular ramps connected at an obtuse angle.

Hanging and slanting rafters are used to assemble truss systems. It is time to talk about systems consisting of hanging or napsled rafters.

Hanging

To decide how to install the rafters, you need to know which type will be used when creating the truss system. The choice of mounting methods and type of rafters is influenced by many factors - the roofing coating used, the angle of inclination of the roof slopes, the expected loads from gusts of wind and snow.

Hanging rafters are distinguished by the fact that they rest only on the mauerlat and that they do not use intermediate supports. Such a system of rafters creates a strong horizontal expansion forces acting on the walls of the building. To reduce these efforts, tightenings are installed, at the same time serving as fasteners for rafter legs.

You can have puffs near the power plate or above. With high installation, you need a stronger connection rafters and puffs.

Note! Installation of hanging rafters is possible only when the span of the roof is not more than 12 meters.

Impulsive

If during the construction of the house it was planned to erect an internal load-bearing wall, the roof of the house is made of glazed rafters. The installation of wall mounted rafters is no different from the installation of a frame system.

Fastening rafters can be done in different ways and it depends on the material used for the construction of the walls of the building. On the wooden framework of the tree is made the connection of the rafters with the upper crown. For the frame of the building used mount with top strapping. For a building of stone, the rafters are attached to the support bar.

To prevent small sections of the truss legs from sagging, the struts, bolts and struts are installed using the grid design. For the manufacture of puffs on the rafter foot wood is used only good quality. For large spans for the manufacture of screeds use from 2 to three logs 650 cm long. They are aligned in one plane and fasten together with each other along the length.

For the manufacture of racks and struts using trimming logs with pre-made ottiskoy ends and pattern marking of metal sheets. Having made a preliminary marking, we saw the place for cutting rafters into the power plate.

When constructing the upper part of the truss and walls, beams of the composite type with lamellar dowels are used. Make beams of a composite type of bars, fastening them with pins of wood along the entire length.

Now you know the design of roof systems and how to install different types of rafters on the roof of buildings. To supplement the information obtained from the article with a clear example, we recommend watching a video about installing rafters.

If you have already installed the rafters yourself and you have your own secrets of installation, share with us and our readers, leaving a comment on the article.

Video

Installation of rafters can be done by one person without assistants:

In the following video you will see the errors that are often made during the installation of rafters:

If you decide to build a house or a cottage, or maybe some kind of utility room, then the question will arise how to protect your building from precipitation. The answer is obvious, you need to make a roof.

The roof may be different, but its installation is carried out on the crate, which is stuffed on the roof structure. Therefore, it is necessary to have an idea of ​​how to install rafters on the roof. When building a house, this is probably the most complex structure, but regardless of the variety of roof forms, the basic principles of its construction are identical.

Some features

In their form of the roof can be:

• single-pitch;
• double slope;
• spire-shaped;
• hip;
• hip;
• mansard;
• dome;
• conical;
• flat.

Shed roofs are usually used on farm buildings.

Installing the rafters on the gable roof is not difficult, because they are based on the load-bearing walls.

It is much more difficult to install rafters on mansard and hip roofs, and for installation of dome and conical roofs, it is better to invite specialists.

The most popular material for rafters is wooden beams. Commonly used coniferous wood. Its resinous structure, relatively low weight and relative durability are excellent for this purpose. Choose boards preferably without knots and cracks. It is undesirable to carry out the construction of a rafter frame of fresh boards and bars. The tree must be dried.

Rafters gather in a triangular farm. This design provides maximum rigidity, which directly affects the bearing capacity of the entire structure as a whole.

Elements of truss construction

1. Mauerlat is a square timber that is rigidly fastened along the bearing walls. The main function of the power plate is to evenly distribute the load on the walls of the roof structure itself. Attached to him truss legs. For mauerlat used timber section from 10 to 15 cm.
2. Rafter legs are the main supporting structures from which triangular trusses are assembled. They are installed in increments of 0.6-1.2 m, depending on the expected load.
3. Run - an additional timber on which rafters lean.
4. The leg is designed for mounting racks on it and for evenly distributing the load from them. It is a square timber of the same section as the mauerlat.
5. Tightening is a transverse beam that interconnects pairs of rafter legs, ensuring the rigidity of the triangular truss structure.
6. The crossbar is a wooden beam, which, like a tie, binds the rafter legs. Unlike tightening, it has a smaller cross section; it is installed approximately 50 cm below the top connection point of rafter legs by the cutting method.
7. Racks. With a large width of the house there is a need to strengthen the construction of the truss system. For this, racks are installed, to which the load of the ridge is distributed.
8. The struts are additional diagonal fastening elements that reinforce the design of the truss. Used for mounting large spans.
9. The ridge is the upper part of the connection of rafter legs.
10. The overhang of the roof is part of the rafter legs, which project approximately 40 cm beyond the walls. Their main task is to protect the walls from rainwater that will slide down from the roof.
11. Fillers - are used if the length of the rafter legs is insufficient for the overhang.

Truss systems come in 2 types:

1. Hanging. They are used with a wall width on the front up to 10 m and there are no load bearing walls between them. Rafters in this case rely on the side walls. To compensate for the bursting load, they are joined by tightening. If you plan to make an attic room, you can use instead of tightening the floor beam.
2. Outcast. They are used with a wall width on the front of more than 10 m. Between them there are load-bearing walls. To reinforce the truss structure, a vertical beam is installed in the middle part, through which the load from the ridge is distributed on the floor and load-bearing walls.

Work on the installation of a truss frame, begin with the installation of a power plate. The place to install it is usually provided for in the process of building walls. For this, a small ledge is laid on the outside of the wall. And the mauerlat fits closer to the inner edge. There are many ways to mount it:

• with the help of tied wire;
• anchor bolts;
• using bookmarks wooden caps;
• using bookmarks pieces of reinforcement.

The installation site of the power plate is necessarily waterproofed, and the timber itself is treated with an antiseptic. It should be noted that the cant is chosen as the maximum length to reduce the number of joints. If the length of the beam is not enough, the connection is made using an oblique gash and then connect the 2 parts with nails, screws, brackets. In this case, it is advisable to do it over 1 m

Making rafter legs begins with cutting pieces of the required length. It is necessary to take into account that for rafters it is better to take boards with a section of 50x20 than 10x10. With the same cross-sectional area, the bearing capacity of the first will be higher.

If the length of the truss board is insufficient, they can be spliced ​​with an overlap or with the help of overlays.

Important: the connection should not be located in the middle of the rafter foot, but should be offset by 1/3 of the total length. This is the best option to ensure rigidity.

For a small building trusses, it is better to gather everything on the ground and then lift them up.

It is necessary to install rafters from extreme gable farms. With the help of the construction level, the verticality of their installation is controlled. On the bottom and top, it is advisable to stretch the building cord for precise installation of intermediate trusses.

Installation of rafter legs is carried out with a step of 0,6-1,2 m. Farms are fixed among themselves by temporary stumbling.

When all the trusses are installed in the upper belt, they are held together by the board. After that, you can remove the temporary fixers.

If the span is longer than 6 m and there is a load-bearing wall in the center of the house, then the rafters need to be installed a little differently. For this purpose, the supports are mounted in the center, on which the ridge bar is mounted. To it separately attached rafters. Installation, as in the previous case, begins with extreme supports. Between them, the construction cord is stretched to place the remaining rafters in the same plane.

Supports may be several. Between the inner supports, you can install another timber that will strengthen the ridge.

When you decide on the height of the roof, the angle of inclination of the slope, then to facilitate the work on the markup is better to prepare a template. All truss legs are the same, so you can perform the necessary gash on the ground, i.e. Immediately perform all the preparatory activities, and then assemble the structure above.

If you put the rafters without a central girder, then among themselves they can be fastened with an overlap or end-to-end. Fastening at the top point must be done rigidly and below it is advisable to install a waist (bolt).

If you plan to install a central girder, it is better not just to lay the rafters on it, but to run down the rafter in a rafter so that a hook is formed. With it, the rafter leg clings to the girder, preventing it from slipping. The second gash is performed when docked with the power plate.

Important: gash is performed on the rafter leg.

Over time, this can lead to its destruction in the place washed down, an increase in the load at this point on the wall and its destruction.

The load on the roof is distributed from top to bottom, so the rafters will try to spread to the sides. In the previous paragraph, we looked at several options for how to prevent this with the help of gash. Strengthen the construction of rafter legs from the spread can be even hard installation on them bars, which will rest against the mauerlat. Still will give additional rigidity to strengthen the rafters with metal clips. The brackets must be installed so as to compensate for the tensile load.

To summarize: for the roof - a difficult and responsible event. You got acquainted with the basic principles of how to put rafters. If you have a small or medium structure, you can do this work yourself.