Types of gable roof truss system: for small and large houses. Rafter system: types and installation for different forms of pitched roofs Rafter scheme of a gable roof of a wooden house

During the construction of private houses, the roof is most often made gable. There are reasons for this. First, it is reliable. Handles wind and snow loads well. The second - it is compatible with any roofing. The third is relatively inexpensive. The fourth is a simple design that is difficult to spoil. Fifth - it looks attractive. All this, and also the fact that a do-it-yourself gable roof is built without special knowledge, determines its popularity.

Do-it-yourself assembled gable roof ready for installation of roofing

Step-by-step installation of a gable 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 processing of wood. This step is required if you bought fresh lumber, not dried.

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

Timber must be dried in ventilated stacks. To do this, they are laid in short pieces of boards. They are placed a meter from the edges and further through the meter. Spacers must be installed under the bottom

We will talk about the main stages of assembly, about how to make a gable roof with your own hands in this section.

Mauerlat

The assembly of the gable roof truss system begins with the installation of the Mauerlat. It must be set strictly horizontally, therefore, before starting installation, the horizontalness of the wall to which it is attached is carefully checked, if necessary, it is leveled with cement mortar. You can continue work after the solution gains 50% strength.

Depending on the system, this is a beam with a 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 played by the upper crown. If the walls are made of light building blocks - foam concrete or aerated concrete and others - their rigidity is not enough to redistribute the load. In this case, a reinforced concrete belt is made over the last row of masonry, into which embedded fasteners are embedded - wire or studs. A bar or board is then mounted on them.

There are several ways to connect walls and Mauerlat:

• In the masonry (in the reinforced concrete belt) a smooth rolled wire of large diameter is fixed (two ends stick up). Holes are then made in the board in the necessary places, into which the wire is threaded. She then twists and bends.
• Studs with a diameter of at least 12 mm are immured in the wall. Under them, holes are made in the Mauerlat, a beam / board is placed) and tightened with nuts with wide washers.
• Aligning the beam or board along the outer or inner edge of the wall, take a drill with a diameter of 12 mm, make holes for the anchor bolts. They (the same diameter of 12 mm) are hammered to the very hat, then tightened with a key.

The distance between the studs (wire) should not be more than 120 cm. Cut-off waterproofing must be laid on the wall (belt) under the Mauerlat. It can be rolled roofing felt or waterproofing in two layers, it can be smeared with bituminous mastic.

Rafter installation

There are more than a dozen types of gable roof truss systems. First of all, you need to choose what yours will look like. Further, in order to make it easier to work, a template is made from thin boards for all cuts, cuts and other similar details. To do this, you may need to assemble the first form on the roof, and then make templates for the finished one.

The assembly order depends on the type of truss system. If the rafters are layered, they are installed gradually, assembling from the elements directly on the roof. In this case, it is convenient if the beams of the ceiling are laid and, if possible, the draft flooring of the attic or attic.

In systems with hanging rafters, a farm is assembled on the ground - a ready-made triangle of puffs and rafter legs with all the required struts, racks. The required number of farms is assembled at once. Then they are lifted to the roof, placed vertically there and attached to the Mauerlat.

On the one hand, this is convenient - it is easier to work on the ground, with a high assembly speed, the accuracy is high: one farm is not much different from the other, which simplifies the procedure. But it can be difficult to raise finished trusses, especially for large buildings. To make this easier, two inclined boards are installed, which at one end rest against the ground, and the other sticks out a little above the wall. Farms are brought closer to this “lift”, one by one they are installed below, ropes are tied and pulled along the boards to the roof. In the absence of a winch or crane, this is the most acceptable method.

The assembly of rafters requires certain knowledge: how and in what order to mount them, how to mark and make cuts. See the video for the assembly of one of the schemes with a headstock.

Assembly order of the truss system

Everything, the do-it-yourself gable roof is assembled and ready for installation of roofing material.

The process of installing the rafters itself raises enough questions, but there are many ways and it is impossible to tell about them all. See one of them in the video. The system is large and went up to the roof in parts, and there it was already assembled into a single structure. It is convenient for large houses.

Features of the installation of the truss system of a wooden house

The difference between wooden houses is that the log house shrinks, and this leads to a change in the geometry of the truss system. If the elements are fixed rigidly, the roof may fall apart. Therefore, the mounts are made floating. There are special sliding fasteners, which in this case attach the rafters to the upper crown and to the girders, if 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 support is placed strictly perpendicular. If necessary, a platform is cut out under it. Mark the mount so that the hook is in the lowest position or near it. They are mounted on special self-tapping screws that come with the kit (ordinary ones do not fit). If the installation is done on a log, so that the rafter leg does not slip along it, a semicircular hole is cut out in the lower part, on which it will rest.

Such fasteners are sold on any construction market, it is called "slippery". How to attach the slippery to the beam, see the video.

Video on assembling and installing a gable roof truss system

It is not easy to build a gable roof with your own hands: there are a lot of subtleties and nuances, there are different ways of fastening, building up. Describing them in words is a thankless job. This is the case when it is better to see. Below is a selection of videos that you might find useful.

Video report on how a gable roof is made

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

Two types of rafter connection: rigid and sliding

Video about the two most problematic types of connections.

How to determine the angle of the rafters

Full video report on the assembly of the truss system

This movie is just under an hour long, but the entire process is shown from start to finish with plenty of detail. The roof is placed on, but when installed on buildings of a different type (except for wooden houses), there is no difference.

You will be able to build a reliable house if you build a quality roof for it. To do this, choose a good project, calculate how many materials will be needed to build one or another part of the house. Do the fastening of the rafters of your gable roof in good faith.

Do not forget that you will need to make high-quality waterproofing throughout the house and on the roof, insulate your home. Choose the best roofing material you can afford. For each type of roof, the rafters are made in their own way.

You don't have to build as you see fit. There are certain, proven technologies for building houses. Study the instructions, buy the necessary materials and proceed on your own or with helpers to build your home.

For example, according to the norms, the truss system is considered reliable when it can withstand a pressure of 200 kg per m2. First, decide what kind of roof you will make over the house, and then study the features of installing rafters for it.

In this article

How to give strength to the truss system?

Ideally, when you built a country cottage with your own hands. You can choose the design of the house and the layout of the rooms as you like. You will personally choose and order high-quality material and take part in all stages of construction, and then the arrangement of your home. In such a house, where every corner is familiar, it will be pleasant to live.

About rafter legs

A large load falls on the rafters - the weight of the roof. They must be of high quality, reliable and well fastened.

Layered rafters include the following materials:

• lying down;
• Rafter legs;
• Racks;
• Struts.

The legs of the rafter legs are bars of medium thickness. They are installed along the slopes. It is the rafters that keep the roof from deflecting in one place or another. The weight load of the coating is distributed to other parts of the roof.

Structures are made layered when there are too large runs between vertical posts. When you are given a project, the step between the rafters will already be calculated there. The fastening of the rafters on a gable roof should be such that the roof after installation remains strong and lasts a long time. Racks are provided here, which similarly support the roof.

Types of rafters

The rafters are included in the roof frame and can be according to their specifications. sloping and hanging characteristics. Let's take a closer look at each type:

• The layered under 2 heels have supports and they are reliable. The fastening of the rafters to the Mauerlat is such that the lower end rests on the Mauerlat or on the upper crown of the log house located on the ceiling. The lower one can rest on another rafter located in the run. This beam is horizontal and lies under the ridge. In the first case, the truss system is spacer, in the second - non-spacer.
• Hanging rafters with their top rest against one another. And the bottom is located on another beam, which is called a puff. It connects the heels located below from 2 rafter legs. It turns out a triangle, which is called a truss truss. Due to the tightening, there is no strong stretching of the materials. And this means that the load on the walls will only go from top to bottom. This design of rafters is called spacer. Its advantage is that it does not create additional load on the walls of the house.

When you purchase beams for rafters, do not be too lazy to drive to the warehouse. The wood should be seasoned, not wet, even and not chipped, with no signs of mold or bugs. Buy only high-quality material, give up the bad. Then you will treat the bars with an antiseptic composition so that they do not become moldy or insects spoil them.

Fixing the roof beams

The beds serve as a support for the bars and so the run is supported. The legs of the rafter will rest against the Mauerlat with one of the ends, and with the second into the runs. They are attached to the latter.

Struts are made to make the rafter legs even more stable.

Make sure that the connections between the parts are strong and reliable. Fasten the parts to each other:

• tie-in method;
• nails;
• anchor bolts;
• Self-tapping screws are used.

Mounting methods

When you are just starting work on the construction of the roof, you need to attach the Mauerlat around the perimeter of your walls. What it is? A large beam, it is attached to the load-bearing walls of the house using anchor bolts. Mauerlat is the basis for a roof with rafters.

Before assembling the truss truss, you must carefully cut all the planks with beams and beams. They are cut at an angle.

At the top, where the base of the Mauerlat, the rafters must be fastened end-to-end using screws. Want to avoid cracks? Drill a hole slightly smaller than the screw itself.

The most popular slings made of wood. They are preferred by the vast majority of those under construction. The material is lightweight but durable. Both an experienced builder and a beginner who decides to build a house on their own will be able to work with him.

We install rafters on a gable roof on our own

Many make such a design when the rafter legs hang down. The system is good for both home and bath. Some work can be done on the ground, and then lift the bonded material to the installation site. There is relatively little lumber for such a structure, which will allow you to save.

1 triangle of rafters is required, which is made according to clear dimensions and adhering to the rules. Made rafters, which will have well-measured and fastened crossbars with puffs, are pulled onto the roof. Here they need to be placed in certain places vertically and very evenly. Attach them to the ridge with Mauerlat.

If the slopes near the roof are longer than 4.5 m, then in order for the system to be stable and more reliable, you need to install racks in a vertical position. One of their ends will support the rafter leg, 2 will rest directly on the beam located on the ceiling.

Do this and it does not matter which rafters you installed: layered or hanging. When slopes are added to a structure, it becomes stiffer. Do not forget that the rafters are most often attached to a ridge beam with a Mauerlat. A reliable gable house will come out.

How to avoid additional payments?

Entrust the creation of a project at home to a professional. He will tell you what diameter in section the beams are needed, the length of the slats and other details. After all, the specialist knows that the rafter system holds the roof. It takes the biggest load and needs correct calculations, high-quality building materials.

It’s better not to ask advice from house builders like yourself. Yes, they built their house, but how strong is it? Not known.

It is best to contact a familiar foreman and ask him for practical advice. After all, he owns the documentation. There are clear standards for the permissible load per 1 m2, which must be followed when building a house. The documentation states what kind of load is given and what material will cope with it.

Take a notebook with a pen to a meeting with the foreman and immediately write down his advice. So, you definitely won’t forget anything, you won’t mix it up. Build it the way he expertly recommends.

For gable roofs, most owners make rafters from wood. Choose the one that has matured. Now process it carefully so that the mold does not start, the bug cannot undermine.

When you assemble the structure, make sure that the angle between the rack with the struts is no more than 45 degrees. Wooden beams must be cut obliquely so that the construction truss tilts at an angle of 40 degrees.

Rafter parts can be attached to each other not only with brackets, but also with corners. Get the right size metal corners to attach the rafters to the Mauerlat. The latter in any of the parts must be strong and reliable. Parts of the system can be interconnected with nails with cutouts, corners with screws, and other devices.

When you build a roof, do not fuss. Everything must be done soundly and thoroughly. After all, even wooden frame houses cost at least 50 years, and log cabins and 100.

Your task is to adhere to technology, not to make mistakes anywhere so that the roof does not warp after a year or 5. Consult with craftsmen and experienced comrades who have already made roofs for themselves or to order, and gradually build a roof.

Rafters serve as the basis of the entire roof structure, and their installation is one of the most important tasks in building a house. The frame of the future roof can be made and installed independently, observing the technological features of roofs of different configurations. We will give the basic rules for the development, calculation and selection of the truss system, and also describe in stages the process of installing the "skeleton" of the roof.

Rafter system: rules for 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 rafter structure, the following factors are taken into account:

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

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

Coefficients, necessary standards and calculation formulas are contained in engineering and construction reference books

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

Roof structure elements

The truss 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, well-dried wood with a moisture level of up to 25% is used.

The wooden structure has one significant drawback - over time, the rafters can be deformed, so metal elements are added to the supporting system.

On the one hand, the metal adds rigidity to the truss structure, but on the other hand, it reduces the life of the wooden parts. Condensation settles on metal platforms and supports, which leads to decay and damage to the wood.

Advice. When installing a truss system made of metal and wood, care must be taken that the materials do not come into contact with each other. You can use moisture barriers or apply film insulation

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

The choice of truss system: hanging and hinged structures

There are two types of roof structures: hanging (spacer) and layered. The choice of system is determined by the type of roof, floor material and natural conditions of the region.

hanging rafters rely solely on the outer walls of the house, intermediate supports are not involved. Hanging type rafter legs perform work on compression and bending. The design creates a horizontal bursting force that is transmitted to the walls. With the help of wooden and metal puffs, this load can be reduced. 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 additional supports are not provided.

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

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

Features of the arrangement of rafters on different roofs

Gable roof

The gable roof, according to building codes, has an angle of inclination 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 - gentle roofs in order to minimize pressure on the structure.

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

For a gable roof, a layered and hanging truss system is used.

hipped roof

All roof slopes have the same area and the same angle of inclination. There is no ridge run here, and the rafters are connected at one point, so the installation of such a structure is quite complicated.

It is advisable to install a hipped roof 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 a rack supporting the junction of the rafter legs.

It is possible to create a hipped roof without a rack, but at the same time, the structure must be strengthened with additional modules - rack 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 angle of inclination of the slope of such a roof does not exceed 40 °. Diagonal runs are usually done with reinforcement, since they account for a significant part of the load. Such elements are made from a double board and a durable beam.

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

The truss structure of a hipped roof may include very long diagonal elements (more than 7 m). In this case, a vertical rack must be mounted under the rafters, which will rest on the floor beam. Sprengel can be used as a support - the beam is located in the corner of the roof and is fixed on adjacent walls. The sprengel farm is reinforced with struts.

broken roof

Sloping roofs are usually created to equip a larger attic. The installation of rafters with this version of the roof can be divided into three stages:

1. Installation of a U-shaped structure - supports for purlins that hold the rafter legs. The base of the structure is floor beams.
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 rafter legs.

Gable roof: do-it-yourself installation of rafters

Calculation of the angle of inclination and loads

The calculation of a gable roof, of course, can be done independently, but it is still better to entrust it to professionals in order to eliminate errors and be sure of the reliability of the structure.

When choosing the angle of inclination, it is necessary to take into account that:

• an angle of 5-15 ° is not suitable for all roofing materials, so first choose the type of coating, and then make the calculation of the truss system;
• at an angle of inclination over 45 ° - material costs for the purchase of the components of the "roofing pie" increase.

Snow load limits range from 80 to 320 kg/m2. The design coefficient for roofs with a slope of less than 25° is 1, for a roof with a slope of 25° to 60° - 0.7. This means that if 140 kg of snow cover falls on 1 m2, then 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 wind pressure fluctuations are taken. The value of the constant load is determined by summing the weight of all components of the "roofing cake" per m2 (on average - 40-50 kg/m2).

Based on the results obtained, 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

Do-it-yourself installation of rafters begins with the installation of a Mauerlat, which is fixed with anchor bolts to the longitudinal walls.

Further construction of the structure is carried out in the following sequence:

Installation of rafters: video

Ways to connect the elements of the truss structure: video

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When planning the construction of low-rise residential, utility or commercial buildings, most designers choose a gable roof structure. This is due to the relatively simple installation technology, increased reliability of the design, effective removal of precipitation from the roof and unpretentiousness to operating conditions. However, to achieve all the benefits, you need to correctly design and install the rafters for a gable roof with your own hands.

Calculation of the length and pitch of the rafters

When installing rafters for a gable roof with your own hands, you need to observe the fixing step of 0.6-1 m. The choice depends on the calculated loads, taking into account the margin of safety. The smaller the step, the stronger the structure and the greater the consumption of building materials. A large interval of 0.8-1 m is allowed to be used only when laying light roofing sheets and slope angles of 15 0 -20 0. It is recommended to choose a step within 0.6-0.8 m.

The length of the beams, knowing the angle of inclination of the slopes and the distance between the two walls of the object, is quite simple to calculate using the Pythagorean theorem. However, the actual length must be increased by 60-70 cm, which will go to their docking, as well as to the overhang of the slopes of about 0.5-0.6 m.