Installation of the truss system. Do-it-yourself truss system - features of design and installation

A gable roof or gable roof is a roof with two slopes, i.e. having 2 inclined surfaces (slopes) of a rectangular shape.

The gable roof frame, due to its design features, ideally combines ease of installation and maintenance with reliability and durability. These and many other parameters make the construction of a gable roof a practical and rational solution for private and commercial housing construction.

In this article, we will consider how to make a gable roof truss system with your own hands. For effective perception of the material, it is presented in the form of step-by-step instructions from A to Z, from selection and calculations, to installation of a Mauerlat and a crate under the roof. Each stage is accompanied by tables, diagrams, drawings, drawings and photos.

The popularity of the roof with a house is due to a number of advantages:

• design variability;
• simplicity in calculations;
• natural flow of water;
• the integrity of the design reduces the likelihood of leaks;
• profitability;
• preservation of the useful area of ​​​​the attic or the possibility of arranging an attic;
• high maintainability;
• strength and wear resistance.

Types of gable roof

The installation of a gable roof truss system depends primarily on its design.

There are several options for gable roofs (types, types):

The most common version of the roof device due to its simplicity and reliability. Due to the symmetry, a uniform distribution of loads on the load-bearing walls and the Mauerlat is achieved. The type and thickness of the insulation do not affect the choice of material.

The cross section of the beam makes it possible to provide a margin of bearing capacity. There is no possibility of bending the rafters. Supports and spacers can be placed almost anywhere.

A clear drawback is the impossibility of arranging a full-fledged attic floor. Due to sharp corners, “blind” zones appear that are unsuitable for use.

The device of one angle more than 45° leads to a decrease in the amount of unused area. There is an opportunity to make living rooms under the roof. At the same time, the requirements for the calculation are increasing, because. the load on the walls and foundation will be distributed unevenly.

This roof design allows you to equip a full-fledged second floor under the roof.

Naturally, a simple gable truss roof differs from a broken one, not only visually. The main difficulty lies in the complexity of the calculations.

The design of the gable roof truss system

Building a roof of any complexity with your own hands requires knowledge of the purpose of the main structural elements.

The locations of the elements are shown in the photo.

• Mauerlat. Designed to distribute the load from the truss system to the load-bearing walls of the building. For the arrangement of the Mauerlat, a beam of durable wood is selected. Preferably larch, pine, oak. The cross section of the beam depends on its type - solid or glued, as well as on the estimated age of the structure. The most popular sizes are 100x100, 150x150 mm.

  Advice. For a metal truss system, the Mauerlat must also be metal. For example, a channel or an I-profile.

• rafter leg. The main element of the system. For the manufacture of rafter legs, a durable beam or log is used. The legs connected from above form a farm.

The silhouette of the roof truss determines the appearance of the structure. Examples of farms in the photo.

Rafter parameters are important. They will be discussed below.

• puff- connects the rafter legs and gives them rigidity.

• Run:

• Skate run, mounted at the junction of one rafter to another. In the future, a roof ridge will be installed on it.

• Side runs, they provide the truss with additional rigidity. Their number and size depend on the load on the system.

• Rafter rack- vertically located beam. It also takes on part of the load from the weight of the roof. In a simple gable roof, it is usually located in the center. With a significant span width - in the center and on the sides. In an asymmetrical gable roof - the installation location depends on the length of the rafters. With a sloping roof and the arrangement of one room in the attic attic, the racks are located on the sides, leaving free space for movement. If there are supposed to be two rooms, the racks are located in the center and on the sides.

The location of the rack depending on the length of the roof is shown in the figure.

• Strut. Serves as a support for the rack.

Advice. Installing the brace at an angle of 45° significantly reduces the risk of deformation from wind and snow loads.

In regions with a significant wind and snow load, not only longitudinal struts are installed (located in the same plane with the rafter pair), but also diagonal ones.

• Sill. Its purpose is to serve as a support for the rack and a place for attaching the strut.

• crate. It is intended for movement during construction works and fixing of roofing material. It is installed perpendicular to the rafter legs.

Advice. An important purpose of the crate is to redistribute the load from the roofing material to the truss system.

The presence of a drawing and a diagram indicating the location of all the listed structural elements will help in the work.

Advice. Be sure to add data on the passage of the ventilation shaft and chimney to the scheme of the gable roof truss system.

The technology of their device is determined by the type of roof.

The choice of material for rafters

When calculating the material for a gable roof, you need to choose high-quality wood without damage and wormholes. The presence of knots for beams, Mauerlat and rafters is not allowed.

For boards, there should be a minimum of knots, and they should not fall out. Wood must be durable and treated with the necessary preparations that will enhance its properties.

Advice. The length of the knot should not exceed 1/3 of the thickness of the timber.

Calculation of the truss system of a gable roof

The calculation of material parameters is an important stage, so we present the calculation algorithm step by step.

It is important to know: the entire truss system consists of many triangles, as the most rigid element. In turn, if the slopes have a different shape, i.e. are an irregular rectangle, then you need to divide it into separate components and calculate the load and the amount of materials for each. After calculations, summarize the data.

1. Calculation of the load on the truss system

The load on the rafters can be of three types:

• Permanent loads. Their action will always be felt by the truss system. Such loads include the weight of the roof, lathing, insulation, films, additional elements of the roof, finishing materials for. The weight of the roof is the sum of the weight of all its constituent elements, it is easier to take into account such a load. On average, the value of the constant load on the rafters is 40-45 kg / sq.m.

Advice. To make the margin of safety for the rafter system, it is better to add 10% to the calculation.

For reference: The weight of some roofing materials per 1 sq.m. presented in the table

Advice. It is desirable that the weight of the roofing material per 1 sq.m. roof area, did not exceed 50 kg.

• Variable loads. They operate at different times and with different strengths. Such loads include: wind load and its strength, snow load, precipitation intensity.

In fact, the roof slope is like a sail and, if you take into account the wind load, the entire roof structure can be destroyed.

The calculation is carried out according to the formula: wind load is equal to the indicator for the region, multiplied by the correction factor. These indicators are contained in the SNiP "Loads and Impacts" and are determined not only by the region, but also by the location of the house. For example, a private house surrounded by high-rise buildings has fewer loads. A detached country house or cottage is experiencing increased wind loads.

2. Calculation of the snow load on the roof

The calculation of the roof for snow load is carried out according to the formula:

The total snow load is equal to the weight of the snow multiplied by the correction factor. The coefficient takes into account wind pressure and aerodynamic influence.

The weight of snow, which falls on 1 sq.m. roof area (according to SNiP 2.01.07-85) is in the range of 80-320 kg / sq.m.

The coefficients showing the dependence on the slope angle are shown in the photo.

Nuance. With a slope angle of more than 60 ° snow load does not affect the calculation. Since the snow will quickly slide down and will not affect the strength of the timber.

• Special loads. Accounting for such loads is carried out in places with high seismic activity, tornadoes, storm winds. For our latitudes, it is enough to make a safety margin.

Nuance. The simultaneous action of many factors causes a synergy effect. This is worth considering (see photo).

Assessment of the condition and bearing capacity of walls and foundations

It should be borne in mind that the roof has a significant weight that can harm the rest of the building.

Determination of the roof configuration:

• simple symmetrical;
• simple asymmetric;
• broken line.

The more complex the shape of the roof, the greater the number of roof trusses and truss elements is needed to create the necessary margin of safety.

The angle of inclination of a gable roof is determined primarily by the roofing material. After all, each of them puts forward their own requirements.

• soft roof - 5-20°;
• metal tile, slate, corrugated board, ondulin - 20-45 °.

It should be noted that increasing the angle increases the area of ​​\u200b\u200bthe space under the roof, but also the amount of material. What affects the overall cost of work.

Nuance. The minimum slope angle of a gable roof must be at least 5°.

5. Calculation of the pitch of the rafters

The pitch of the rafters of a gable roof for residential buildings can be from 60 to 100 cm. The choice depends on the roofing material and the weight of the roof structure. Then the number of rafter legs is calculated by dividing the length of the slope by the distance between the rafter pairs plus 1. The resulting number determines the number of legs per slope. For the second number, you need to multiply by 2.

The length of the rafters for the attic roof is calculated using the Pythagorean theorem.

Parameter "a"(roof height) is set independently. Its value determines the possibility of arranging a dwelling under the roof, the convenience of being in the attic, the consumption of material for the construction of the roof.

Parameter "b" equal to half the width of the building.

Parameter "c" is the hypotenuse of the triangle.

Advice. To the value obtained, you need to add 60-70 cm for sawing and taking the rafter leg out of the wall.

It should be noted that the maximum length of the beam is 6 r.m. Therefore, if necessary, the timber for the rafters can be spliced ​​(building, joining, joining).

The method of splicing the rafters along the length is shown in the photo.

The width of the rafters for the roof depends on the distance between opposite load-bearing walls.

7. Calculation of the section of the rafters

The cross section of the gable roof rafters depends on several factors:

• load, we already wrote about it;

• type of material used. For example, a log can withstand one load, a beam - another, a glued beam - a third;

• rafter leg length;

• type of wood used in construction;

• distance between rafters (rafter pitch).

You can determine the cross section of the beam for the rafters, knowing the distance between the rafters and the length of the rafters, using the data below.

Rafter cross section - table

Advice. The larger the installation step of the rafters, the greater the load on one rafter pair. So, the cross section of the rafters needs to be increased.

Dimensions of lumber (beams and boards) for a gable truss system:

• thickness (section) of the Mauerlat - 10x10 or 15x15 cm;

• the thickness of the rafter leg and puffs is 10x15 or 10x20 cm. Sometimes a beam of 5x15 or 5x20 cm is used;

• run and strut - 5x15 or 5x20. Depending on the width of the leg;

• rack - 10x10 or 10x15;

• bed - 5x10 or 5x15 (depending on the width of the rack);

• thickness (section) of the roof lathing - 2x10, 2.5x15 (depending on the roofing material).

Types of gable roof truss system

For the considered roof structure, there are 2 options: layered and hanging rafters.

Consider each type in detail in order to make an informed choice.

hanging rafters

They are used with a roof width of not more than 6 r.m. The installation of hanging rafters is carried out by attaching the legs to the load-bearing wall and the ridge run. The design of hanging rafters is special in that the rafter legs are under the influence of a bursting force. Hanging rafters with a puff installed between the legs can reduce its influence. The puff in the truss system can be wooden or metal. Often puffs are placed at the bottom, then they play the role of load-bearing beams. It is important to ensure that the puff is securely fastened to the rafter leg. Because a bursting force is also transmitted to it.

Advice.
The higher the puff is located, the greater the strength it should have.
If the puff is not installed, the load-bearing walls can simply “disperse” from the pressure created by the truss system.

Rafters

They are used in the arrangement of roofs of any size. The design of the layered rafters provides for the presence of a bed and a rack. Lying lying parallel to the Mauerlat takes on part of the load. Thus, the rafter legs seem to be inclined towards each other and are supported by the rack. The rafter legs of the layered system work only for bending. And the ease of installation also tips the scales in their favor. The only downside is the stand.

Combined

Due to the fact that modern roofs are distinguished by a large variety of shapes and complexity of configurations, a combined type of truss system is used.

After choosing the type of truss system, you can accurately calculate the amount of materials. Record the calculation results. At the same time, professionals recommend drawing up drawings for each element of the roof.

Installation of a gable roof truss system

After the gable roof rafters are calculated, installation can begin. We break the process into stages and give a description of each of them. You will get a kind of step-by-step instruction containing additional information on each stage.

1. Attaching the Mauerlat to the wall

The beam is installed along the length of the wall on which the rafters will rest.

In log cabins, the role of the Mauerlat is played by the upper crown. In buildings built from porous material (aerated concrete, foam concrete) or brick, the Mauerlat is installed along the entire length of the load-bearing wall. In other cases, it can be installed between the rafter legs.

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Since the length of the mauerlat exceeds the standard dimensions of lumber, it has to be spliced.

The connection of the Mauerlat with each other is done as shown in the figure.

How to connect the Mauerlat?

Washed down the bars is made only at an angle of 90 °. Connections are made using bolts. Nails, wire, wooden dowels are not used.

How to fix the Mauerlat?

The Mauerlat is installed on top of the wall. Mounting technology provides for several ways to mount the Mauerlat:

• strictly in the center of the bearing wall;
• offset to one side.

Advice.
Mauerlat cannot be placed closer than 5 cm to the outer edge of the wall.

To protect the beam for the Mauerlat from damage, it is laid on a layer of waterproofing material, which most often acts as an ordinary roofing material.

The reliability of fastening the Mauerlat is an important aspect of construction. This is due to the fact that the roof slope is like a sail. That is, it experiences a strong wind load. Therefore, the Mauerlat must be firmly fixed to the wall.

Methods for attaching the Mauerlat to the wall and rafters

Anchor bolts. Ideal for monolithic construction.

Wooden dowels. Are used for fellings from a log and a bar. But, they are always used with additional fasteners.

Staples.

Stud or armature. It is used if the cottage is built of porous materials (aerated concrete, foam concrete).

Sliding fastening (hinged). A bunch in this way allows you to ensure the displacement of the rafter legs when the house shrinks.

Annealed wire (knitting, steel). It is used as an additional fastening in most cases.

2. Production of roof trusses or pairs

Installation is carried out in two ways:

• installation of bars directly on the roof. It is not used often, since it is problematic to perform all the work, measurements, trimming at a height. But it allows you to completely do the installation yourself;

• assembly on the ground. That is, individual elements (triangles or pairs) for the truss system can be assembled at the bottom, and then raised to the roof. The advantage of such a system is faster work at height. And the disadvantage is that the weight of the assembled structure of the truss truss can be significant. To lift it, you need special equipment.

Advice. Before assembling the rafter legs, you need to mark up. It is very convenient to use templates for this purpose. The truss pairs assembled according to the template will be exactly the same. To make a template, you need to take two boards, the length of each of which is equal to the length of one rafter, and are interconnected.

3. Installation of rafter legs

The collected pairs rise up and are installed on the Mauerlat. To do this, at the bottom of the rafter legs, you need to make a drink.

Advice. Since the slots on the Mauerlat will weaken it, you can only cut down on the rafter leg. To wash down was the same and fit snugly to the base, you need to use a template. It is cut out of plywood.

Methods for attaching the rafter leg are shown in the figure.

You need to start installing rafter pairs from opposite ends of the roof.

Advice. To properly install the rafter legs, it is better to use temporary struts and struts.

A twine is stretched between the fixed pairs. It will simplify the installation of subsequent rafter pairs. And also, will indicate the level of the skate.

If the rafter system is mounted directly on the roof of the house, then after installing the two extreme rafter legs, the ridge support is installed. Further, half of the rafter pairs are attached to it.

It is worth noting that the opinions of professionals differ on this issue. Some advise using a staggered mounting order, which will evenly distribute the increasing load on the walls and foundation more evenly. This order involves the installation of one rafter in a checkerboard pattern. After part of the rafter legs is installed, the missing parts of the pair are mounted. Others insist that you need to do a consistent installation of each pair. Depending on the size of the structure and the configuration of the truss, the reinforcement of the rafter legs is carried out with props and racks.

Nuance. Additional structural elements are connected by cutting. It is preferable to fix them with building brackets.

If necessary, you can lengthen the rafter leg.

Methods for splicing rafter legs are shown in the photo.

Advice. The method by which the Mauerlat is lengthened (washed down at 90 °) cannot be used in this case. This will weaken the rafter.

4. Installing the gable roof ridge

The ridge knot of the roof is made by connecting the rafter legs at the top.

Roof ridge device:

• Method without using a support bar (see fig.).

• A method using a rafter bar. Timber is needed for large roofs. In the future, it can become a support for the rack.

• The method of laying on the beam.

• A more modern version of the manufacture of the ridge knot can be considered the method shown in the photo.

• Cutting method.

After the truss system is installed, we make a major fixing of all structural elements.

5. Mounting the roof sheathing

The crate is mounted in any case, and is designed for more convenient movement along the roof during work, as well as for fixing roofing material.

The step of the lathing depends on the type of roofing material, for example:

• under the metal tile - 350 mm (the distance between the two lower boards of the crate should be 300 mm).
• under a professional flooring and slate - 440 mm.
• under the soft roof we lay a continuous crate.

Rafter system of a gable roof with an attic - video:

Conclusion

As you can see, despite the seeming simplicity, the installation of a gable roof truss system contains many pitfalls. But, based on the above recommendations, you can easily build a reliable structure with your own hands.

Is it time to install the roof? The very first thing you need to do is the installation of the truss system. This work is very important and difficult, and therefore it is necessary to carefully read our advice.

A bit of theory - what you need to know about the truss system?

First of all, you need to talk about the types of truss systems and their characteristics. So, this system consists of the following elements:

• rafter legs;
• racks and vertical supports;
• struts;
• puffs - an element that connects the rafter legs.

You should also distinguish between rafters by type. Rafter systems are divided into:

• Layered. They should be used if the building has internal partitions or other supports. In this case, the "legs" of the structure must rest on both the outer walls and the inner ones.
• Hanging - in which the "legs" of the structure rest only on the outer walls. A distinctive feature of this design is that for its design it is necessary to tighten due to high spacer loads.

Several important technical specifications

When choosing a method for installing rafters, it is necessary to assess the complexity of the work and the weight of the future structure. If the assembled product is lightweight or you can bring special lifting equipment to the site, then it is best to assemble the rafters on the ground, and then lift them to the roof of the building, where you can do all the other work. If the structure is characterized by a large weight, then it will have to be assembled directly on the roof - this is easier and safer.

It is very important to correctly connect the upper parts of the rafters. This work can be done in several ways. First of all, end-to-end, when cuts are made at the required angle on opposite rafter legs. Next, the rafters need to be docked along the ends obtained and secured to several nails. For a more secure connection, secure the products with a metal strap.

It is possible to fasten the rafter legs with an overlap - in this case, the structural elements are in contact with each other by planes. If you are going to make a rafter system in a house with fronts that are made of logs, then the rafters must be placed on the walls using the sliding fastener method. Thanks to this, you will be able to avoid deformation of the roof in case of shrinkage of the house.

If you decide to use this method, then you need to consider that it is quite difficult to do it yourself. Fasteners are made as follows: the “legs” of the rafters must be placed with a gap, fastening them together using a specialized movable metal element. Now we proceed to the direct construction of the truss system with our own hands.

Mauerlat - what is it and why?

The construction of the rafter system must begin with the installation of a Mauerlat - these are the foundations for the future design. Mauerlat is a log or beam, which is attached around the entire perimeter of the outer walls. Undoubtedly, it is possible to make a structure without a Mauerlat, but it will be quite difficult and even risky to build such a structure with your own hands. It is very important to follow all the recommendations exactly so that the base for the truss system performs its functions 100%.

Important Tips:

• Before laying the mauerlat, the walls must be insulated with a suitable waterproof material. To save money, you can put several layers of roofing material.
• Installation of logs is carried out on a reinforced belt with a small indent from the edges of the walls.
• It is best to choose logs of antiseptic wood with a section of 10 * 15 cm.

For the convenience of doing work with your own hands, the bars must first be laid out from one front to the other along the entire length of the wall. After that, you can take measurements: lay out the bars according to the level, watching the evenness of the distance between them. Next, you can attach the bars to the walls. As we have already said, it is preferable to carry out installation on a reinforced belt, using anchor bolts as a fastening product - it is better to fasten them when pouring a reinforced belt. Also do not forget to drill holes in the beam itself.

Important: if you want to achieve a perfectly even position of the bolts, before pouring the “belt”, attach the board to the bolts and give the fasteners a vertical position using a square.

We put the base prepared with our own hands on stands consisting of planks, after which we carefully lower the bars onto the bolts, each time taking out a plank. At the end, we wind the washer to the bolt. Now it's time to learn how to make a truss system with your own hands.

Do-it-yourself installation of a truss system

We have already talked about the installation of the Mauerlat. Now it's time to move on to the main point of installing the truss system - this is the installation of floor beams and a ridge beam. But first things first. Floor beams - beams with a section of 20 * 10 or 15 * 10 cm. The length of the products should be such that, when laid on the walls, the beams form an extension that will correspond to the width of the eaves.

In simple words, the bars should go beyond the walls at a certain distance. The bars are installed in one direction, leaving an equal distance between them.

To ensure that there are no errors during the execution of work, a clear sequence of actions should be followed:

• We mount the boards with our own hands, retreating from the edge of the walls by an average of half a meter.
• We stretch the cord between the bars - it will serve as a kind of "beacon" for the installation of the following beams.
• The distance between the "legs" of the structure must be chosen based on the section of the rafters. So, if you decide to choose "floor" boards, 5 * 15 cm in size, then the step should be approximately 60 cm. It is worth noting that this will greatly simplify all further work. And all due to the fact that the width is most often 60 cm, which means that nothing will need to be trimmed.
• We proceed to the installation of transverse bars, which in one part should be in contact with the extreme beam, and the second - go beyond the walls. The gap between such jumpers should be about 1 m.
• We attract the beams to the base (Mauerlat) with the help of nails, you can also use self-tapping screws and steel corners (for reliability).

To make it as convenient as possible for you to carry out work during the construction of the truss system with your own hands, lay ordinary boards on the beams.

Now it's time to talk about installing a ridge beam. This stage consists of several steps:

• Installation of auxiliary racks, which are U-shaped struts made of wood. Professional experts advise that the height of the spacers be equal to the height of the first floor.
• We assemble racks at opposite ends of the structure and put intermediate beams, maintaining a step of 2.5 meters.
• After mounting the racks, we lay a ridge beam on top (a wooden board with a section of 5 * 20 cm). Fix the structure with self-tapping screws.

Since the rafters must have the same length, it is advisable to make a template in advance to determine the length. To do this, we take one board measuring 2.5 * 15 cm, apply it to the beam and to the ridge, and put marks at the points of contact and saw off the unnecessary part - you can make blanks using this template. True, it is worth noting that not everyone can achieve perfect evenness, and therefore get ready for the fact that during the installation process you will have to use the saw more than once.

If you neglect this advice, then the skate may bend, which may make the design not so reliable.

After you have installed the truss system, you need to make waterproofing, create a crate and cover the structure with roofing material. Now you know how to assemble the truss system - the roof is almost ready. We hope our tips will help even you to do the work yourself.

For a good roof, it is very important that every step in its creation goes perfectly. The basis of the entire roof structure is the truss system, the configuration of which determines the type of the upper part of the building. There are different types of such systems, among which you need to choose the most suitable for yourself, because the functionality and quality of the entire roof depend on the correctness of your choice.

Types of truss system

The device of the roof during the construction of the building is essential. And in order for the roof to be strong enough, special attention is paid to the supporting systems, which are divided into:

• combined;
• hanging;
• layered.

A roof is a fairly complex structure, consisting of a variety of parts. The main requirement for the roof, - it is the ability to protect the structure from all kinds of weather conditions and withstand different loads.

The main loads of the roof fall on the truss system, so it is very important to choose the right materials, calculate everything correctly and make the installation in accordance with the technology.

Installation of hanging rafters

Hanging rafters are designed for buildings that do not have capital partitions inside, and the distance between the common load-bearing and side walls is no more than 10 meters. The roof structure in this embodiment lies on the main walls of the building, but because of this, it is subjected to high loads. To make the tension a little weaker, additional parts (puffs or crossbars) are used that fasten the truss in a horizontal position.

Depending on the length of the span, various reinforcing elements are used in the design of the hanging rafters.

The lower puffs are connected at the base of the rafters and can be used as beams for the attic floor, while they must be laid on the Mauerlat. For the manufacture of hanging rafters, a board with a section of 50x200 mm is usually taken, however, each individual building needs its own specific calculations.

The sequence of actions for the installation of hanging rafters:

Installation of layered rafters

Rafter rafters are mainly installed in those buildings where there are load-bearing partitions. They are much easier to mount than a hanging system, since strong load-bearing walls located inside the house serve as a reliable support for the rafters. In addition, this system requires a minimum amount of building materials.

The ridge board in this case serves as a reference point. Such a roofing system is installed in one of three options:

To fix the rafters in the lower part of the roof, it is necessary to use sliding fasteners, which relieve the load-bearing partitions from additional stress. In this case, the rafters are not fixed very tightly, so that when the building shrinks, they can move without overloading the roof structure.

But in some cases, you can use a spacer system that is tightly attached to the Mauerlat below. Struts and puffs are mounted in the structure to reduce the load on the walls. This method is called complex, because it combines elements of two systems.

Such a roofing system is mainly used for the construction of private buildings, so it is worth mentioning the installation work, which is carried out in the following sequence:

Installation work on the installation of the layered system should begin with the flooring of the boards on the floor beams. Such a device will help to carry out work comfortably and safely.

Combined roofing system

Combined rafters have in their design elements from layered and hanging systems. They are used in the manufacture of mansard roofing. The walls of the rooms on the second floor are obtained thanks to the vertical posts, which are the fulcrum for the rafters.

The horizontal bars, which were installed on top of the racks, perform two functions: for the upper slopes they are a Mauerlat, and for the side ones they are a ridge bar. Some part of the truss system, which is connected at the top of the ends of the racks, simultaneously becomes a puff for the upper elements and a crossbar for the slopes located on the sides.

In the combined roof, fragments of layered and hanging truss systems are used

To increase the strength of the structure, it is necessary to install struts that secure the rafters and vertical roof racks. It is a little harder to make combined rafters than other systems, but the laboriousness of the work is offset by an increase in the bearing characteristics of the roof and the presence of a full-fledged room under the roof.

Photo gallery: roof system options

In the construction of the hip roof, layered rafters are used. For the roof-envelope, a rafter system similar to the mansard is erected. In the structures of broken roofs, at the joints there are special rafters that support the valleys. Multi-gable roofs consist of several different truss systems combined into one whole. the same element can be both a power plate and a skate

Installation of the roof truss system

The truss system is made of coniferous wood. You can use boards or timber, which are treated with antiseptic agents before installation. Fasteners can be as follows:

• wooden scarves;
• metal plates;
• various cuts;
• nails.

Starting the installation of rafters, they remove the level of floors and load-bearing walls, after which waterproofing is laid. The under-rafter structure is necessary in order to prevent the deformation of the rafters. As supporting elements that give the truss system stability, can serve:

• sunbeds;
• struts;
• runs;
• racks.

Roof insulation is necessary, but for this you should choose a material for hydro, heat and vapor barrier. Installation is carried out in layers and only in the sequence in which it is necessary: ​​initially steam, then heat, and finally moisture-proof material.

Before laying the roofing, the necessary protective materials are installed in compliance with the established ventilation gaps.

To ensure long-term operation of the truss system, the necessary air circulation is arranged by installing ventilation holes. To avoid leaks, “collars” are made near the holes, which do not allow water to penetrate under the roof.

Video: do-it-yourself installation of a truss system

How is the mauerlat attached

Mauerlat is the foundation of the roof, so you should treat it responsibly. Otherwise, roof repairs in the future will be inevitable. Sequence of work:

Methods for attaching a roofing mauerlat and splicing rafters

Mauerlat is attached to the walls of the building along the entire perimeter, while the fasteners should be in close proximity to the inside of the wall. Outside the house, the wooden part is protected by a slight protrusion of the wall. The place for fastening is also initially determined.

How to fix the mauerlat to the wall

Mauerlat can be attached to the wall in the following ways:

How to fix the rafters to the Mauerlat

All options for attaching the roof truss system to the Mauerlat can be divided into the following types:

How the rafters are attached at the level of the ridge

The most common option for attaching rafters to a ridge is a butt joint:

Rafter splicing options

In the construction industry, various options for truss splicing are used everywhere, while choosing a certain technology, one must pay attention to the design characteristics of the truss system, which are affected by:

• purchased materials;
• technical data of the construction site;
• rafter installation step.

Rafters can be spliced ​​as follows:

Each type of truss system has its own characteristics and is suitable only for a certain type of roof structure. It is from the correct installation of the rafters that not only the reliability, but also the strength of the roof depends, therefore, this stage of work must be approached with the utmost responsibility.

The construction of a reliable truss system is one of the most difficult tasks in the construction of the roof of a country house, cottage or garage. Nevertheless, do not rush to give up - today we will refute the popular belief that such work is beyond the power of a beginner. Knowing the rules for calculating, sawing and installing a roof frame, you can build a roof no worse than specialists. In turn, we will try not only to talk about the device, design and features of the construction of various types of truss systems, but also share the secrets of experienced craftsmen.

What is called the truss system and how it works

Any, even the most seedy roof, is based on a strong power frame, called a truss system. The rigidity of the roof, and hence the ability to withstand even the strongest wind and snow loads, depends on how correctly this structure is mounted.

The truss system is the power frame of the roof, which perceives the entire wind and snow load.

The best material for the manufacture of rafters (trusses) is considered to be a bar or thick board made of softwood. And there is an explanation for this - pine or spruce lumber has a relatively low weight, and the presence of natural resins makes it quite durable. Even if the timber will have a small residual moisture, it will not lead when it dries, which is no less important factor than ease of use and long service life.

Depending on the size of the roof, the supporting structural elements can have a cross section from 50x100 mm to 200x200 mm or more. In addition, the length of the roof directly affects the number of rafters, because they are installed in small steps - from 60 cm to 1.2 m.

Structural elements of the truss system

The main requirement that is put forward to a wooden frame is the ability to resist bending and torsion. For this reason, a triangle shape is best suited for timber frame trusses. However, they can consist of several parts:

• rafter legs - the base of the roof frame, which has the greatest impact on the size and geometry of the slopes;
• crossbars (puffs) - boards that pull together a pair of rafter legs;
• runs - transversely installed bars, due to which the rafters are connected into a single structure;
• racks - vertical supports that serve to support the rafter legs or prevent deflection of the runs;
• struts - the same racks, only set at an angle to the vertical;
• beds - boards attached to the floor of the attic, on which supports are installed;
• mauerlat - a support beam installed on the bearing walls, to which the lower parts of the rafter legs are attached;
• filly - pieces of timber or boards that are nailed to the lower ends of the trusses and serve to equip roof overhangs.

Additional elements of the truss system make the roof frame more durable, rigid and stable

When choosing the design of the roof frame, it is important to find the very middle ground that will allow you to get a solid and reliable structure at minimal cost. For this reason, you can deviate a little from the established canons, if it does not concern the rigidity of the entire structure. For example, it is quite possible to do without fillies, and form a cornice overhang due to longer rafter legs. Or use not a solid Mauerlat, but pieces of timber laid only at the attachment points of the rafter legs - it all depends on the engineering ingenuity and experience of the roofer.

Rafter classification

Depending on the design of the roof and the purpose of the attic, the wooden frame may consist of several types of rafters:

Features and varieties of truss systems

To make an informed choice, you need to understand the features of various types of truss systems and know the strengths and weaknesses of each design.

Roof frame with hanging rafters

Since the principle of attaching hanging rafters does not imply additional support points, this design is used for buildings with a width of no more than 6 m. Installation of unsupported trusses involves attaching each pair of legs to opposite main walls, while their upper parts are fixed directly to the ridge run.

The roof frame with hanging rafters transfers only vertical forces to the walls, therefore it has simpler attachment points to load-bearing walls

During operation, a force acts on the hanging rafters, tending to push the structure apart. To compensate for the bursting force, a crossbar made of a wooden beam or a metal profile pipe is installed between the rafter legs. If the attic space will be used for household purposes, then the upper jumper is attached as close as possible to the ridge, and the lower edges of the pairs of rafter legs are connected with puffs. Such a scheme allows you to increase the useful height of the attic, without reducing the strength of the frame at all. By the way, if the lower jumpers are made of timber with a section of more than 100x100 mm, then they can also be used as load-bearing beams. It is necessary to ensure a reliable connection of puffs and rafter legs, since significant bursting forces also act on the place of their fastening.

Roof with rafters

Rafter rafters require the installation of at least one support, so they are used for buildings with internal load-bearing walls. The maximum length of a single span should not exceed 6.5 m, otherwise the strength and rigidity of the roof frame will suffer. To increase the width of the roof, the truss system is reinforced with intermediate supports. Even one additional rack allows you to increase the width of the roof up to 12 m, and two - more than 15 m.

The rafter system is ideal when a large roof width is required.

The stability of slope trusses can be increased by using a sub-rafter frame with girders, posts and struts. In addition, this rafter system requires much less lumber costs. Versatility, strength and cost-effectiveness have long been appreciated by both construction companies and individual developers, most often using roof structures with layered beams in their projects.

Combined options

Today, the roofs of country houses amaze with the elegance of design, the quirkiness of shapes and the variety of configurations. There is only one way to build such complex structures - by combining both types of truss systems in one frame.

The combination of layered and hanging trusses allows you to get a truss system of any configuration

Even for the construction of not the most complex sloping roof, both truss systems are used at once. The right-angled triangles located on the sides are layered truss structures. And they are connected due to the upper screed, which at the same time plays the role of a puff for the upper hanging rafters.

The procedure and rules for the installation of roof frames

Since two types of roof frames are used in the construction of roofs, we will consider the installation technology for each structure separately. However, before proceeding with construction work, it is necessary to study the methods of fastening structural elements to each other.

Roof construction with hanging rafters

It has already been mentioned above that hanging rafters are most often used in the construction of small or undemanding buildings. A log house in this case is an almost ideal option, since you can do without a Mauerlat. The lower part of the rafter legs is attached to the upper crown or the edges of the ceiling beams (matrices) protruding beyond the perimeter of the walls. In the latter case, the puff must be moved up - this will allow you to put the beam on top of the finishing log and make the attic more comfortable.

To increase the height of the attic space, the puff should be installed as close as possible to the top of the roof

Preparatory work

The geometry of the slopes depends on how well the beams will be prepared for the rafter legs. A cord stretched between nails driven into the extreme beams will help to level the supporting surfaces..

1. It is necessary to cut down the slab, having received flat platforms for the installation of trusses. After that, you should definitely check how accurately they lie in the same plane. This can be done using a long straight rail and a level.

   Before installing the trusses, the supporting surfaces are aligned with the cord

2. After removing excess wood, in each beam you need to make a recess under the rafter spike. You can draw the places of future nests using the same nails and cord as in the previous case. Although the recesses for the rafters can be made both before and after the manufacture of the trusses, experts advise doing them first - this will allow you to try on with higher accuracy and convenience.

   The method of attaching the rafters depends on many factors - the type of support beams, their cross section, the features of the roof overhang, etc.

3. Professional roofers recommend installing an additional reference point in the center of the span of each tong - a vertical rail. One of its sides is used as an axis of symmetry, which will make it possible to monitor the strict observance of the geometry of the structure.

   In order to simplify the process of marking and mounting the roof frame, use vertical rails installed along the center line of the roof

Rafter manufacturing

In order for the rafters to have the same dimensions and configuration, they are made according to a pre-made template. For its manufacture, we suggest using the following instructions:

1. Take two slatted boards and bolt them together to form a drop-down compass design. The threaded connection should not be tightened strongly - the structure should rotate around the top. Be sure to check that the slats are 10-15 cm longer than the rafters - this will be needed to take into account the height of the thrust tooth.

   The simplest template allows you to get roof trusses of the same size and configuration

2. On the rail set as a guide, make two marks. The lower one should correspond to the height of the truss system, and the upper one should be separated from it by the height of the mounting ledge.
3. Install the template on the mat so that the corners of the boards rest against the recesses for the rafter teeth.

   In order for the structure to successfully cope with bursting loads, the thrust tooth at the end of the rafter leg is inserted into a recess on the floor beam

4. Align the axis of rotation of the "compass" with the upper mark on the rail and set aside the height of the spike from the lower corners of the jig.
5. Lower the template down and cut the teeth along the drawn line. After that, raise the device to the roof and insert the spikes into the nests on the mother. Check the coincidence of the sample axis with the lower mark on the vertical rail. If necessary, move the bolt to the desired side and fix the angle between the boards with a cross member.

   Several methods are used to fasten trusses - it all depends on the type of support beams, the design of the roof frame and the section of its elements

6. Having adjusted the template in height, apply vertical abutment lines to each board. In conclusion, measure the length of the crossbar and build a template from the scraps of the boards for making overlays on the tops of the trusses.

   To attach the crossbar to the rafters, linings from pieces of an inch board are used.

After the template is lowered to the ground, it is disassembled and cuts are made according to the markings. In addition, they construct a separate pattern, along which the ends of the rafter legs will be cut. The manufacture and assembly of hanging rafters is most often done below, raising finished structures to the roof. If the weight and dimensions of the assembled trusses do not allow them to be pulled up manually, then the assembly is carried out on the spot. At the same time, the components of the truss system are fixed with nails ranging in size from 100 to 200 mm.

How to install roof rafters

In order to raise and install farms, you will need the help of at least one person. Fitting and setting the rafters on a plumb line alone is an extremely difficult task - you will have to fasten them to the struts more than once and repeatedly descend from the roof to control the deviation from the vertical plane.

With the help of a rafter tooth, it is possible to obtain such a reliable connection that only one nail can be used for the final fixation.

Raising the assembled rafters up, first mount the extreme structural elements, and then the central and intermediate ones. To strengthen the structure, a support is installed under each leg:

Having set the hanging rafters according to the level, they are fixed with temporary struts. After that, the lower ends of the beams are nailed to the mat or floor beams.

Various temporary structures greatly simplify the process of installing rafters by level.

It is not worth resorting to newfangled methods of fixing with the help of various corners and perforated plates. A reliable "old-fashioned" method of fastening with nails 200 mm long or construction staples will be much better both in terms of strength and reliability, and in terms of cost. At this stage, do not worry about the design looking flimsy.. After the remaining elements of the truss system are installed and the crate is completed, the structure will acquire the necessary rigidity and stability.

Video: making and installing do-it-yourself hanging rafters

Features of the installation of layered rafters

The process of manufacturing and installing layered rafters is generally very similar to the construction of a hanging roof frame. The main difference is at the top point and it is due to the fact that the tops of the layered beams rest on the ridge run. In this case, the connection with the latter is performed in several ways:

• simple adjoining apart (in parallel to each other);
• with the implementation of a vertical joint (the same as when connecting the paired legs of a hanging truss);
• by tightly fitting the beams to the upper beam (using a vertical cut or notch).

If the design of the wooden frame provides for the support of trusses on the side girder, then the rafters are joined end-to-end, and recesses are made at the junction with the girder.

For fastening layered rafters, nails, building brackets or linings made of wood and metal are used.

To ensure the strength of the structure, the cuts should not be too deep.. Experts recommend making recesses no more than a quarter of the thickness of the beam or a third of the width of the board.

Individual developers most often resort to installing rafters in the following way:

• the upper part rests on the ridge beam by means of a vertical cut;
• from below, the rafter legs are held by a corner cut.

For marking it is convenient to use a construction square. After the scale is selected, on the sides of the right-angled triangle, the values ​​\u200b\u200bof the rise of the slope and half the span are set aside. Thanks to this, it will be possible to obtain the slope angle of the slope without resorting to mathematical calculations.

For the manufacture of rafters, we suggest using the most convenient method:

At first glance, this method is very tricky. However, even a cursory acquaintance with the given instruction is enough to master it perfectly. Of course, it is possible to set aside the necessary distances and make markings by calculation, however, when calculating angles and distances, it will be much easier to get confused.

It should be remembered that the cuts made in the rafter legs must be exactly the same, otherwise the roof slope will be uneven. To do this, you can use a wooden block as a template. It is only important that its thickness does not exceed 1/3 of the thickness of the workpiece.

For the most common slope angles, there are templates that professionals have already worked on calculating the configuration of. Using one of these patterns, you can significantly simplify the task of marking the corners of the cuts.

Templates with marked corners of the cuts allow you to simplify the process of manufacturing rafters

Assembly and installation of a layered structure

Video: installation of rafter legs of a layered roofing system

Methods for connecting rafter logs

When choosing a beam for overall roof trusses, you have to look for a reasonable compromise between the length and thickness of the rafters. The reason for this is the peculiarities of the standard range of lumber, in which longer beams have an increased section. On the other hand, their use is not always justified both technologically and due to an increase in the cost of the structure. The way out of this situation is to lengthen the rafter legs by splicing. The stiffness and mechanical strength of the beam depends on how correctly the joint is made, so the connection is made strictly according to a certain method.

Oblique cutting method

The method of merging with an oblique cut consists in the fact that inclined cutouts (cuts) are formed on the mating parts of the bars. They should be carried out very carefully - after combining both parts of the timber, there should be no gaps, otherwise deformation will appear at the junction.

When splicing with an oblique cut, there should be no gaps and gaps between the mating surfaces, which can weaken the rafter and cause its deformation

When making cuts, a small transverse section is left with a height of at least 15% of the thickness of the rafter - the presence of the end part will make the connection more durable. To calculate the optimal length of the oblique cut, it is necessary to multiply the height of the beam at the place of the cut by two. The cut is fastened with nails, clamps or bolted connections.

Coupling

To lengthen the rafter by rallying (stitching), the edges of the boards are overlapped and a rack is installed in the center of the junction zone. The fastening of the elements is carried out with the help of nails, which are hammered according to a certain pattern:

• along the edges of the ends - every 45–90 mm;
• along the edges of the stitched boards - in a zigzag manner, with a step of 50 cm.

Joining the boards by rallying eliminates the need for additional overlays, however, it requires the installation of an additional support in the center of the junction area

In order for the beam to successfully cope with operational loads after docking, the length of the rallying section (T) is calculated by the formula T = 0.42 × L, where L is the length of the overlapped span.

frontal stop

The frontal extension connection is that the edges of the individual parts of the rafters are carefully trimmed and butted together. For fastening, linings made of lumber with a thickness of at least 1/3 of the section of the main beam are used. The length of the overlays is determined by the formula L = 3 × h, where h is the width of the board.

When splicing with a frontal stop, a monolithic structure will be obtained only with the correct placement of fasteners

The fixation of all parts is carried out using a nail fight or bolted connections. In the first case, nails are hammered in two parallel rows, trying to place fasteners in a zigzag pattern. The threaded connection is performed in a checkerboard pattern, determining the number of bolts depending on the length of the lining.

Compound length extension

To build up a rafter leg, it is not at all necessary to use both parts of the same section. With a compound build-up, a single element can be lengthened due to two boards that are sewn onto its side planes. The resulting gap is filled with l = 2 × h lumber cuts with a step L = 7 × h, where h, as before, is the thickness of the element being extended.

Composite extension of rafters allows you to attach crossbars, supports and other structural elements in the most convenient way

Tips from experts on the manufacture of rafters and assembly of the roof frame

When starting to independently design and install a truss system, be sure to consult with experienced roofers regarding the features of building roofs in your area. Perhaps their advice will keep you out of trouble and help you save time and money. In turn, we offer several recommendations that will help make the design more reliable and durable:

1. If a minimum cross-section bar is used to make a Mauerlat or top trim, then cuts can weaken it. For this reason, cutouts should only be made at the lower ends of the rafter legs.
2. In order to prevent precipitation from falling on the wooden frame and walls of the house, the roof must have an overhang. For its arrangement, pieces of timber (filly) are used, with which the length of the rafter legs is increased, or larger trusses are made.
3. Connection using cuts at an angle of 90 o cannot be used- in this case, the resistance of the element to load forces is significantly reduced.
4. If the elements of the truss system are connected by threaded fasteners, then wide washers or metal plates are installed under the heads of the bolts and nuts. Due to the increased area, the fasteners will not be pressed into the wood.
5. All wooden parts of the structure must be thoroughly impregnated with an antiseptic and fire retardant.
6. When determining the cross section of the puffs, they are guided by how close they will be to the ridge. The shorter the connecting bar, the greater the load on it and the more powerful lumber and bolted fasteners are used.
7. When determining the cross section of a beam for the manufacture of rafters, do not forget to take into account the thickness of the heat-insulating layer.

Video: recommendations of experts on the correct connection of the elements of the roof frame

https://youtube.com/watch?v=GbTAu5-flfs

Modern materials and technologies allow you to build a roof of any configuration and purpose. Given this diversity, it is simply impossible to consider in detail all the options within the framework of one article. However, based on the basic principles of construction discussed here, you can easily cope with the most complex design. The main thing is to pay attention to the little things, to be attentive and accurate in work. And then the roof will be not only a reliable functional superstructure, but also a real decoration of your home.

Thanks to my versatile hobbies, I write on various topics, but my favorite ones are engineering, technology and construction. Perhaps because I know many nuances in these areas, not only theoretically, as a result of studying at a technical university and graduate school, but also from the practical side, since I try to do everything with my own hands.

A gable roof is one of the most popular in individual construction. It is quite simple to build, it takes little material, and it provides good protection from rain, snow and wind. The construction of the roof can be considered as a separate stage, consisting of its design, calculation of the necessary materials, installation of the truss system, insulation, and laying of the roofing material.

The rafter system is the skeleton of the roof, and only with its correct calculation and fastening is it possible to have a long service life of the entire roof, without distortions, leaks and collapses. It is best to entrust the installation of rafters to a team of professionals, but if this is not possible, it is really possible to saddle it on your own, but in any case, you cannot do without assistants.

Material for rafters

In order to most accurately calculate the required amount of material, it is worth drawing (on your own or in a special program) a plan of the truss system and its layout. Given the length of the boards and beams, it is possible to arrange the elements in such a way that the amount of waste will be minimal.

For the manufacture of rafters, wood of the highest category is used - without knots and cracks. The standard dimensions of the material are 50 * 150 mm with a length of up to 6 m, but if the beams must be more than 6 m, then boards 180 mm wide are needed to avoid sagging.

Attention should be paid not only to the quality of the wood, but also to the fasteners. Self-tapping screws for fastening the structure must be from a trusted manufacturer, with gaskets of 2 mm or more. It is also necessary to take into account the need for antiseptic and fire-fighting wood treatment.

When erecting rafters, you will need tools:

1. measuring instruments - an accurate and long tape measure (preferably 6 m or more), a level, a cord for plumb lines, a pencil for marking,
2. hammers and nails, nail puller,
3. carpentry knife, hacksaw, saw (or chainsaw),
4. drill, screwdriver and screws,
5. axe,
6. templates for fastening roof structure elements at the right angle,
7. stop for installing rafters - a bar 6 * 6 cm with a corner 40 * 40 mm attached on both sides,
8. ropes for lifting rafters.

Types of roof structures and its elements

The truss system for large and small roofs will differ somewhat in design, and its device also depends on the presence of a support beam and its location, the angle of the slopes.

The main elements of the truss system:

• mauerlat - support beam with a thickness of 150 * 150 mm, for a more even distribution of the load on the walls,
• rafter leg,
• rafter leg, or crossbar,
• rack,
• run - a board 50 * 200 mm, to which the rafter legs are attached at the top,
• sill.

Rafters can be hanging and layered. The hanging ones are attached with their ends to the walls of the house and the roof ridge, with their large length, it is necessary to compensate for the bending and compression loads with ties connecting the rafter legs. Rafter rafters can be erected in houses that have load-bearing walls inside and you can use a support beam to which the rack is attached. The ends of the rafters rest on this post and on the outer walls of the house, the middle part being supported by piers. Optimally, if the structure has both hanging and layered rafters, this makes the roof more durable.

Installation of rafters

Stage 1 - installation of the Mauerlat

First of all, a Mauerlat is attached to the outer walls with anchor bolts. It is desirable that it be solid or with a minimum of connections, this will increase the strength of the structure. Mauerlat must be located absolutely evenly, since the accuracy of the installation of the entire roof depends on this. If necessary, gaskets can be inserted under it, they are squeezed into the protruding parts. In the future, rafter legs will be attached to the Mauerlat.

Stage 2 - run

The use of a rafter design with a purlin increases the reliability of the roof and simplifies assembly, since each pair of rafters can be mounted separately. The run is installed at the highest points of the frontal walls and fastened with metal corners and anchor bolts. Its ends must be waterproofed.

Stage 3 - assembly of truss sections

Before assembling the rafters, blanks are cut, trying to use the material so that the amount of waste is minimal. If necessary, the boards can be extended, paying attention to the reliability of the connection, for example, with overlays or overlap. It should be located at least a meter from any of the edges. It is better not to place the connection exactly in the middle, since the bearing capacity of the leg is reduced, the optimal location is one third of the total length.

The rafters are assembled according to the drawings, the templates (the angles at which the elements should be located to each other) greatly simplify this work. The easiest way is to assemble the truss sections on the ground, then lifting them up. However, this may require a winch or a few helpers.

First, all elements are laid out relative to each other as they will be located in the finished section. Corners and gaps are carefully adjusted. Then the linings are fastened with nails to the upper part of the rafters, in the middle the legs are connected with ties. At least 5 nails must be driven into each nail connection. Temporary straps are screwed to the bottom of the legs.

Stage 4 - installation of the truss system

The rafters are raised gradually. First, by 30 degrees, then with the help of insurance and cables up to 60. At this stage, crossbars and ties are nailed to the back of the structure fixed with cables. Then the section rises to a vertical position, which is checked with a level, and the structure is fixed with bolts and corners to the run and to the Mauerlat.

You can expose the rafters in two ways:

At the first, the first and last sections are installed, a cord is pulled between them and all other parts are mounted along it.

In the second case, the rafter sections are installed above one half of the house, and the second half of the structure hangs on the run and leans against them. Next, the first section is mounted on the opposite side, and gradually the rest, this process resembles the closing of curtains and ends in the middle of the roof.

After installing the truss system, you can begin to manufacture the crate, vapor barrier and insulation.