home > Floor repair > Installation of rafters on a gable roof. The rafter system of a gable roof and its device Variants of the truss system of a gable roof of a wooden house

Installation of rafters on a gable roof. The rafter system of a gable roof and its device Variants of the truss system of a gable roof of a wooden house

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

frame gable roof by virtue of design features perfectly combines ease of installation and maintenance with reliability and durability. These and many other parameters make the construction of a gable roof practical and rational decision 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 a step-by-step instruction 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. Thanks to symmetry, uniform distribution loads on load-bearing walls and Mauerlat. 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 rafter roof differs from a broken line, 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.

Truss truss silhouette defines appearance buildings. 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 (located in the same plane with the rafter pair) are installed, 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 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. Valid in different periods 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, given 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 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. Standing separately Vacation home or cottage experience 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 large quantity roof trusses and sub-rafter elements are 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 is worth noting that maximum length timber - 6 m.p. 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. Installation of hanging rafters is carried out by attaching the legs to the load-bearing wall and 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, allow you to 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 characterized by a wide variety of shapes and complex configurations, it is used combined view rafter system.

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 waterproofing material, which most often acts as an ordinary roofing material.

Mauerlat fastening reliability important aspect 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). The bundle in this way allows you to ensure the displacement of the rafter legs when the house shrinks.

Annealed wire (knitting, steel). Used as an additional mount 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 roof truss structure 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 spacers.

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. Connect additional elements structures with 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 way in which the Mauerlat is extended (washed down at 90 °) in this case cannot be applied. 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. The bar is needed for big roofs. In the future, it can become a support for the rack.

The method of laying on the beam.

More modern variety manufacturing a 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.

At the heart of each roof is a large number of beams, rafters, racks and runs, which are collectively called the truss system. Over the centuries-old history of types and methods of its organization, a lot has accumulated, and each has its own characteristics in the construction of knots and cuts. We will talk in more detail about what the gable roof truss system can be and how the rafters and other elements of the system should be attached in more detail.

The design of the gable roof truss system

In the context of a gable roof is a triangle. It consists of two rectangular inclined planes. These two planes are connected at the highest point in single system ridge beam (run).

Gable roof scheme

Now about the components of the system and their purpose:

Mauerlat - a timber that connects the roof and walls of the building, serves as a support for the rafter legs and other elements of the system.
Rafter legs - they form the inclined planes of the roof and are the support for the crate under the roofing material.
Ridge run (bead or ridge) - combines two roof planes.
Puff - a transverse part that connects opposite rafter legs. Serves to increase the rigidity of the structure and compensate for bursting loads.
Beds - bars located along the Mauerlat. Redistribute the load from the roof.
Side runs - support the rafter legs.
Racks - transfer the load from the runs to the beds.

Filly may still be present in the system. These are boards that extend the rafter legs to form an overhang. The fact is that in order to protect the walls and foundation of the house from precipitation, it is desirable that the roof ends as far as possible from the walls. To do this, you can take long rafter legs. But the standard lumber length of 6 meters is often not enough for this. Ordering non-standard is very expensive. Therefore, the rafters are simply grown, and the boards with which this is done are called “fillies”.

There are quite a few designs of truss systems. First of all, they are divided into two groups - with layered and hanging rafters.

The difference in the design of layered and hanging rafters

With hanging rafters

These are systems in which the rafter legs rest only on the outer walls without intermediate supports (bearing walls). For gable roofs, the maximum span is 9 meters. When installing a vertical support and a strut system, it can be increased up to 14 meters.

The hanging type of gable roof truss system is good because in most cases there is no need to install a Mauerlat, and this makes the installation of rafter legs easier: no need to make cuts, just mow the boards. To connect the walls and rafters, a lining is used - a wide board, which is attached to studs, nails, bolts, crossbars. With such a structure, most of the bursting loads are compensated, the impact on the walls is directed vertically downwards.

Types of truss systems with hanging rafters for different spans between load-bearing walls

Gable roof truss system for small houses

There is a cheap version of the truss system when it is a triangle (photo below). Such a structure is possible if the distance between the outer walls is not more than 6 meters. For such a rafter system, it is possible not to calculate the angle of inclination: the ridge must be raised above the puff to a height of at least 1/6 of the span length.

But with this construction, the rafters experience significant bending loads. To compensate them, or take rafters larger section or the cutting of the ridge part is done in such a way as to partially neutralize them. To give greater rigidity in the upper part, wooden or metal plates are nailed on both sides, which securely fasten the top of the triangle (also see not the picture).

The photo also shows how to grow rafter legs to create a roof overhang. A notch is made, which should go beyond the line drawn from the inner wall upwards. This is necessary to move the incision site and reduce the likelihood of a rafter breaking.

Ridge knot and fastening of rafter legs to the backing board with a simple version of the system

For mansard roofs

The option with the installation of a crossbar is used when organizing a dwelling under the roof - an attic. In this case, it is the basis for filing the ceiling of the room below. For reliable operation systems of this type, the notch of the crossbar must be hingeless (rigid). The best option is semi-pan (see the picture below). Otherwise, the roof will become unstable to loads.

Gable roof truss system with raised tightening and crossbar cutting unit

Please note that in this scheme there is a Mauerlat, and the rafter legs should extend beyond the walls to increase the stability of the structure. To secure them and dock with the Mauerlat, a cut is made in the form of a triangle. In this case, with an uneven load on the slopes, the roof will be more stable.

With such a scheme, almost the entire load falls on the rafters, therefore they must be taken with a larger section. Sometimes the raised puff is reinforced with a suspension. This is necessary to prevent it from sagging if it serves as a support for ceiling sheathing materials. If the puff is short, it can be secured in the center on both sides with boards nailed to the nails. With a significant load and length, there may be several such insurances. In this case, boards and nails are also enough.

For big houses

With a significant distance between the two outer walls, a headstock and struts are installed. This design has high rigidity, since the loads are compensated.

Large span gable roof truss system and ridge and rafter cutting units

With such a long span (up to 14 meters), it is difficult and expensive to make a one-piece puff, because it is made from two beams. It is connected by a straight or oblique cut (picture below).

Straight and oblique cut for tightening connection

For reliable docking, the junction is reinforced with a steel plate mounted on bolts. Its dimensions must be larger than the dimensions of the cut - the extreme bolts are screwed into solid wood at a distance of at least 5 cm from the edge of the cut.

In order for the circuit to work properly, it is necessary to correctly make the struts. They transmit and distribute part of the load from the rafter legs to the puff and provide structural rigidity. Metal strips are used to reinforce the connections.

Fastening struts for the rafter system with hanging rafters

When assembling a gable roof with hanging rafters, the cross-section of lumber is always larger than in systems with layered rafters: there are fewer load transfer points, therefore, each element has a greater load.

How the mansard roof is arranged (with drawings and diagrams) read here.

With rafters

In gable roofs with layered rafters, their ends rest on the walls, and the middle part rests on load-bearing walls or columns. Some schemes burst walls, some do not. In any case, the presence of a Mauerlat is mandatory.

The simplest version of layered rafters

Bezporny schemes and knots of cuts

Houses made of logs or timber do not respond well to spacer loads. For them, they are critical: the wall can fall apart. For wooden houses the truss system of a gable roof must be non-thrust. Let's talk about the types of such systems in more detail.

The simplest non-spacer scheme of the truss system is shown in the photo below. In it, the rafter leg rests on the Mauerlat. In this embodiment, it works on a bend, without bursting the wall.

Simple non-branched gable roof system with rafters

Pay attention to the options for attaching the rafter legs to the Mauerlat. In the first, the support platform is usually beveled, while its length is no more than the cross section of the beam. Cutting depth - no more than 0.25 of its height.

The top of the rafter legs is laid on the ridge beam without fastening it to the opposite rafter. Two shed roofs are obtained according to the structure, which adjoin (but do not connect) one with the other in the upper part.

It is much easier to assemble the option with rafter legs fastened in the ridge part. They almost never give a thrust on the walls.

Mounting option for rafters without spreading on the walls

For this scheme to work, the rafter legs below are attached using a movable joint. To fix the rafter leg to the Mauerlat, one nail is hammered from above or a flexible steel plate is placed from below. See the photo for options for attaching rafter legs to a ridge run.

If the roofing material is planned to be heavy, it is necessary to increase the bearing capacity. This is achieved by increasing the cross section of the elements of the truss system and strengthening the ridge assembly. It is shown in the photo below.

Strengthening the ridge assembly for heavy roofing material or with significant snow loads

All of the above gable roof schemes are stable in the presence of uniform loads. But in practice, this almost never happens. There are two ways to prevent the roof from sliding in the direction of greater load: by installing a brace at a height of about 2 meters or by struts.

Options for truss systems with contractions

The installation of contractions increases the reliability of the structure. In order for it to work normally, at the places where it intersects with drains, you need to attach nails to them. The cross section of the beam for the scrum is used the same as for the rafters.

Schemes of truss systems of gable roofs with fights

They are attached to the rafter legs with bots or nails. Can be installed on one or both sides. The knot for attaching the bout to the rafters and the ridge run, see the figure below.

Fastening the scrum to the rafter legs and the ridge beam

In order for the system to be rigid and not “crawl” even under emergency loads, it is enough in this embodiment to provide a rigid fastening of the ridge beam. In the absence of the possibility of its displacement in the horizontal, the roof will withstand even significant loads.

How to make a gable roof (photo report) read here.

Rafter systems with braces

In these options, rafter legs, which are also called struts, are added for greater rigidity. They are installed at an angle of 45° with respect to the horizon. Their installation allows you to increase the span length (up to 14 meters) or reduce the cross section of beams (rafters).

The strut is simply substituted at the required angle to the beams and nailed from the sides and bottom. An important requirement: the brace must be cut accurately and fit snugly against the uprights and the rafter leg, excluding the possibility of its deflection.

Systems with rafter legs. Above is a spacer system, below is a non-spacer system. The nodes of the correct felling for each are located nearby. Below - possible strut mounting schemes

But not in all houses, the average load-bearing wall is located in the middle. In this case, it is possible to install struts with an angle of inclination relative to the horizon of 45-53 °.

Rafter system with off-center vertical purlin

Systems with braces are necessary if significant uneven shrinkage of the foundation or walls is possible. The walls can sit in different ways on wooden houses, and foundations - on layered or heaving soils. In all these cases, consider the installation of truss systems of this type.

System for houses with two internal load-bearing walls

If the house has two load-bearing walls, two rafters are installed, which are located above each of the walls. Beds are laid on the intermediate load-bearing walls, the load from the rafter beams is transferred to the beds through the racks.

Rafter Systems

In these systems, a ridge run is not installed: it gives expansion forces. The rafters in the upper part are connected to one another (cut and joined without gaps), the joints are reinforced with steel or wooden plates, which are nailed.

At the top without spacer system the bursting force is neutralized by tightening. Please note that the puff is placed under the run. Then it works efficiently (the top diagram in the figure). Stability can be provided by racks, or jointing - beams installed obliquely. In the spacer system (in the picture below), the crossbar is a crossbar. It is installed above the run.

There is a variant of the system with racks, but without rafters. Then a rack is nailed to each rafter leg, which rests on the intermediate load-bearing wall with the second end.

Fastening the rack and tightening in the rafter system without a rafter run

To fasten the racks, nails for 150 mm and bolts 12 mm are used. Dimensions and distances in the figure are in millimeters.

Rafters perform a number of significant roofing functions. They set the configuration of the future roof, perceive atmospheric loads, and hold the material. Among the rafter duties, the formation of even planes for laying the coating and providing space for the components roofing cake. In order for such a valuable part of the roof to flawlessly cope with the listed tasks, information about the rules and principles of its construction is needed. The information is useful both for those who are building a gable roof truss system with their own hands, and for those who decide to resort to the services of a hired team of builders.

Rafter structures for gable roofs

In the device of the truss frame for pitched roofs, wooden and metal beams are used. The starting material for the first option is a board, log, timber. The second is constructed from rolled metal: channel, profile pipe, I-beam, corner. There are combined structures with steel most loaded parts and wood elements in less critical areas.

In addition to the "iron" strength, the metal has a lot of disadvantages. These include heat engineering qualities that do not satisfy the owners of residential buildings. Disappointing need for the use of welded joints. Most often, industrial buildings are equipped with steel rafters, less often private change houses assembled from metal modules.

In the case of self-construction of truss structures for private houses, wood is a priority. It is easy to work with it, it is lighter, “warmer”, more attractive in terms of environmental criteria. In addition, nodal connections do not require welding machine and welding skills.

Rafters - a fundamental element

The main "player" of the frame for the construction of the roof is the rafter, among the roofers called the rafter leg. Beds, braces, headstocks, girders, puffs, even Mauerlat may or may not be used depending on the architectural complexity and dimensions of the roof.

The rafters used in the construction of the gable roof frame are divided into:

Layered rafter legs, both heels of which have reliable structural supports under them. The lower edge of the layered rafter rests on the Mauerlat or on the ceiling crown of the log house. The support for the upper edge can be a mirror analogue of an adjacent rafter or a run, which is a beam horizontally laid under the ridge. In the first case, the truss system is called spacer, in the second, non-spacer.
hanging rafters, the top of which rests against each other, and the bottom is based on an additional beam - puff. The latter connects the two lower heels of adjacent rafter legs, resulting in a triangular module called a truss truss. The tightening dampens the tensile processes, so that only a vertically directed load acts on the walls. The design with hanging rafters, although it is spacer, does not transfer the spacer itself to the walls.

In accordance with the technological specifics of the rafter legs, the structures constructed from them are divided into layered and hanging. For structural stability, they are equipped with struts and additional racks. For the arrangement of supports for the top of the layered rafters, beds and girders are mounted. In reality, the truss structure is much more complicated than the elementary patterns described.

Note that the formation of a gable roof frame can generally be carried out without roof structure. In such situations, the alleged planes of the slopes are formed by slegs - beams laid directly on the bearing gables. However, we are now specifically interested in the device of the gable roof truss system, and it can involve either hanging or layered rafters, or a combination of both types.

Subtleties of fastening rafter legs

Fastening the truss system to brick, foam concrete, aerated concrete walls is made through the Mauerlat, which in turn is fixed with anchors. Between the Mauerlat, which is wooden frame, and walls made of these materials must be laid with a waterproofing layer of roofing material, waterproofing, etc.

The top of the brick walls is sometimes specially laid out so that something like a low parapet is obtained along the outer perimeter. So it is necessary that the Mauerlat placed inside the parapet and the walls do not burst the rafter legs.

The rafters of the frame of the roofs of wooden houses rest on the upper crown or on the ceiling beams. The connection in all cases is made by cutting and duplicated with nails, bolts, metal or wooden plates.

How to do without furious calculations?

It is highly desirable that the cross section and linear dimensions of the wooden beams be determined by the project. The designer will give clear calculation justifications for the geometric parameters of the board or beam, taking into account the entire range of loads and weather conditions. If there is no home design development master at his disposal, his path lies on the construction site of a house with a similar roof structure.

You can ignore the number of storeys of the building under construction. It is easier and more correct to find out the required dimensions from the foreman than to find them out from the owners of a shaky unauthorized construction. After all, the foreman is in the hands of documentation with a clear calculation of the loads per 1 m² of roof in a particular region.

The installation step of the rafters determines the type and weight of the roofing. The heavier it is, the smaller the distance between the rafter legs should be. For laying clay tiles, for example, the optimal distance between the rafters will be 0.6-0.7 m, and for the installation of metal tiles and profiled sheets, 1.5-2.0 m is acceptable. However, even if the step required for the correct installation of the roof is exceeded, there is a way out . This is a reinforcing counter-lattice device. True, it will increase both the weight of the roof and the construction budget. Therefore, it is better to deal with the step of the rafters before the construction of the rafter system.

Craftsmen calculate the pitch of the rafters according to the design features of the building, tritely dividing the length of the ramp into equal distances. For insulated roofs, the step between the rafters is selected based on the width of the thermal insulation boards.

On our site you can find a calculator for calculating a gable roof, which may also help you a lot during construction.

Rafter structures of layered type

Rafter structures of the layered type are much simpler in execution than their hanging counterparts. A justified plus of the layered scheme is to provide full ventilation, which is directly related to the longevity of the service.

Distinctive design features:

Mandatory presence of support under the ridge heel of the rafter leg. The role of a support can be played by a run - wooden beam leaning on racks or on inner wall buildings, or the upper end of an adjacent rafter.
The use of Mauerlat for the construction of a truss structure on walls made of brick or artificial stone.
The use of additional runs and racks where the rafter legs, due to the large size of the roof, require additional support points.

The minus of the scheme is the presence of structural elements that affect the layout inner space operated attic. If the attic is cold and the organization of useful premises is not supposed to be in it, then the layered construction of the truss system for the installation of a gable roof should be preferred.

A typical sequence of work on the construction of a layered truss structure:

First of all, we measure the height of the building, the diagonals and the horizontalness of the upper cut of the skeleton. When identifying vertical deviations of brick and concrete walls, we eliminate them with a cement-sand screed. Exceeding the heights of the log house we squeeze. By placing chips under the Mauerlat, vertical flaws can be dealt with if their magnitude is insignificant.
The floor surface for laying the bed must also be leveled. He, the Mauerlat and the run must be clearly horizontal, but the location of the listed elements in the same plane is not necessary.
We process everything wooden details structures before installation with flame retardants and antiseptics.
on concrete and brick walls we lay waterproofing for the installation of a Mauerlat.
We lay the Mauerlat beam on the walls, measure its diagonals. If necessary, we slightly move the bars and turn the corners, trying to achieve the perfect geometry. Align the frame horizontally if necessary.
We mount the Mauerlat frame. The splicing of the beams into a single frame is carried out by means of oblique cuts, the joints are duplicated with bolts.
We fix the position of the Mauerlat. Fasteners are made either with brackets to wooden plugs laid in the wall ahead of time, or with anchor bolts.
We mark the position of the bed. Its axis should recede from the Mauerlat bars at equal distances on each side. If the run will be based only on racks without lying down, the marking procedure is carried out only for these columns.
We install the bed on a two-layer waterproofing. We fasten it to the base with anchor bolts, connect it to the inner wall with wire twists or staples.
We mark the installation points of the rafter legs.
We cut out racks according to uniform sizes, because our bed is set to the horizon. The height of the racks must take into account the dimensions of the section of the run and the bed.
Installing racks. If provided by the project, we fix them with spacers.
We lay the run on the racks. We check the geometry again, then install the brackets, metal plates, wooden mounting plates.
We install a trial rafter board, mark the places of trimming on it. If the Mauerlat is set strictly to the horizon, there is no need to adjust the roof rafters in fact. The first board can be used as a template for making the rest.
We mark the installation points of the rafters. Folk craftsmen for marking usually prepare a pair of slats, the length of which is equal to the gap between the rafters.
According to the markup, we install the rafter legs and fasten them first at the bottom to the Mauerlat, then at the top to the run to each other. Every second rafter is screwed to the Mauerlat with a wire bundle. In wooden houses, the rafters are screwed to the second crown from the top row.

If the rafter system is made flawlessly, the layered boards are mounted in random order. If there is no confidence in the ideal structure, then the extreme pairs of rafters are installed first. A control twine or fishing line is stretched between them, according to which the position of the newly installed rafters is adjusted.

The installation of the truss structure is completed by installing the filly, if the length of the rafter legs does not allow the formation of an overhang of the required length. By the way, for wooden buildings, the overhang should “go beyond” the contour of the building by 50 cm. If the organization of the visor is planned, separate mini-rafters are installed under it.

Another useful video about the construction of a gable truss base with your own hands:

Hanging truss systems

The hanging type of truss systems is a triangle. The two upper sides of the triangle are folded by a pair of rafters, and the puff connecting the lower heels serves as the base. The use of tightening allows you to neutralize the effect of the thrust, therefore, only the weight of the crate, the roof, plus, depending on the season, the weight of precipitation, acts on walls with hanging truss structures.

The specifics of hanging truss systems

Characteristic features of roof structures hanging type:

Mandatory presence of a puff, made most often of wood, less often of metal.
The ability to refuse the use of Mauerlat. A frame made of timber will be successfully replaced by a board laid on a two-layer waterproofing.
Installation on the walls of ready-made closed triangles - roof trusses.

The advantages of the hanging scheme include the space under the roof free from racks, which allows you to organize an attic without pillars and partitions. There are disadvantages. The first of these is the limitation on the steepness of the slopes: their slope angle can be at least 1/6 of the span of a triangular truss, steeper roofs are strongly recommended. The second disadvantage is the need for thorough calculations for the competent device of cornice nodes.

Among other things, the angle of the truss truss will have to be set with jewelry accuracy, because. the axes of the connected components of the hanging truss system must intersect at a point, the projection of which must fall on the central axis of the Mauerlat or the lining board replacing it.

Subtleties of long-span hanging systems

Puff - the longest element of the hanging rafter structure. Over time, it, as is typical of all lumber, deforms and sags under the influence of its own weight. Owners of houses with spans of 3-5m are not too concerned about this circumstance, but owners of buildings with spans of 6 meters or more should think about installing additional parts that exclude geometric changes in tightening.

To prevent sagging in the installation scheme of the truss system for a large-span gable roof, there is a very significant component. This is a pendant called a grandmother. Most often, it is a bar attached with wooden surfs to the top of the truss truss. You should not confuse the headstock with the racks, because. its lower part should not come into contact with the puff at all. And the installation of racks as supports in hanging systems is not used.

The bottom line is that the headstock, as it were, hangs on a ridge knot, and a tightening is already attached to it with the help of bolts or nailed wooden plates. Threaded or collet type clamps are used to correct slack.

Adjustment of the tightening position can be arranged in the zone of the ridge knot, and the headstock can be rigidly connected to it with a notch. Instead of a bar in non-residential attics, reinforcement can be used to manufacture the described tightening element. It is also recommended to arrange a headstock or suspension where the puff is assembled from two bars to support the connection area.

In an improved hanging system of this type, the headstock is complemented by strut beams. The stress forces in the resulting rhombus are extinguished spontaneously due to the competent arrangement of the vector loads acting on the system. As a result, the truss system pleases with stability with a slight and not too expensive upgrade.

Hanging type for attics

In order to increase the usable space, the tightening of the rafter triangles for the attic is moved closer to the ridge. A perfectly reasonable move has additional advantages: it allows you to use puffs as the basis for filing the ceiling. It is attached to the rafters by cutting with a semi-frying pan with a duplication of a bolt. It is protected from sagging by installing a short headstock.

A noticeable drawback of the attic hanging structure is the need for accurate calculations. It is too difficult to calculate it on your own, it is better to use a ready-made project.

Which design is more cost effective?

Cost is an important argument for an independent builder. Naturally, the price of construction for both types of truss systems cannot be the same, because:

In the construction of a layered structure for the manufacture of rafter legs, a board or beam of small section is used. Because layered rafters have two reliable supports under them, the requirements for their power are lower than in the hanging version.
In the construction of a hanging structure, the rafters are made of thick timber. For the manufacture of puffs, a material similar in cross section is required. Even taking into account the rejection of the Mauerlat, the consumption will be significantly higher.

Saving on the grade of material will not work. For the bearing elements of both systems: rafters, purlins, beds, Mauerlat, attendants, racks, lumber of the 2nd grade is needed. For crossbars and puffs working in tension, you will need the 1st grade. In the manufacture of less responsible wooden slips, the 3rd grade can be used. Without counting, we can say that in the construction of hanging systems, expensive material is used to a greater extent.

Hanging trusses are harvested on open area next to the object, then transported assembled upstairs. To lift weighty triangular arches from a bar, you will need equipment, for which you will have to pay rent. And the project for complex nodes of the hanging version is also worth something.

Video instruction on the installation of a truss structure of a hanging category:

There are actually many more methods for constructing truss systems for roofs with two slopes. We have described only the basic varieties that are actually applicable for small country houses and buildings without architectural designs. However, the information provided is sufficient to cope with the construction of a simple truss structure.

Design options Rafter systems

Layered or hanging
Spacer or non-spacer
Mounting methods

Modern buildings sometimes amaze our imagination with the most unusual forms of roofs. They owe their stylish and spectacular appearance to the variety of truss structures. However, all of them are “assembled” in the skillful hands of the architect-designer, like a constructor, connected in a certain order from standard elements.

Design Options

The truss systems of pitched roofs depend on their features.

Shed – the simplest option in manufacturing. The peculiarity of its design is the absence of a ridge, racks and struts. Such roofs, as a rule, cover buildings with 6-8-meter spans. Despite the simplicity of the design, With a reasonable approach, even such a simple design has its advantages. For example, with south side, directed to the north, you can install fairly large windows. This is the most convenient truss system for an extension, garage, etc., especially since it allows you to "assemble" the roof from large-sized sheet materials.

Another simple and cheap design is gable. However, it is not without its shortcomings. For example, in a conventional roof of this type there is too little space for an attic.

hip- not two, but four-slope. From a certain angle, it resembles an ordinary gable. However, its slopes do not completely cover the surface of the house - the space remaining on the sides is closed by lateral triangular hips. Thus, the roof turns out to be hipped and two types of rafters are used for its construction.

Multi-forceps- this is a design, which, as it were, consists of a combination of gable roofs with multidirectional ridges. The truss system of such roofs is the most expensive, but it makes it possible to equip additional space in the attic.

Shatrovaya, due to its shape resembling a pyramid, it is maximally resistant to wind load. It also doesn't hold snow. And this despite the fact that her rafter system is one of the simplest. True, the absence of gables does not allow even a small room to be equipped in the attic.

Rafter systems

Layered or hanging

The frame for the device consists of triangular-shaped elements, due to which, even when experiencing a large number of variable loads, the structure does not lose rigidity. Rafter systems of pitched roofs are divided into hanging and layered.

The choice of one or another type, method of fastening is based on the following parameters:

the dimensions of the building itself;
the slope and shape of the roof;

Rafters

For buildings with a single or gable roof, the use of layered rafters is more common. This is a structure assembled from short bars or boards, which has two or three points of rigid attachment. In the first version, these are the walls of the building, in the case of a gable, a ridge is added, and the ridge beam in this case must be reinforced with racks. The supports for the latter are beds. The length of the rafters in buildings that are large in size exceeds 6 m. It is possible that additional support structures will need to be installed here. For example, to build inside the main walls or columnar supports.

hanging

This design is characterized by the absence of intermediate supports. Such rafters often cover spans exceeding 7 m. The wall remains the only reference point for the rafter leg. As for the second end, in this case, the upper parts of the rafter beam and the opposite leg are joined. For this use various ways: by means of a slotted spike or metal plates, half-wood connection.

Spacer or non-spacer

The reliability of the roof, first of all, is ensured by a careful calculation of the loads under the influence of which its frame is located. Rafters become, as it were, "conductors" of these loads on the external supports of the structure. The load that the rafters exert on their supports is of two types - expansion and non-expansion.

spacer

The rafter beams in this design work in compression and bending, which causes a significant horizontal expansion force. It is naturally transferred to the walls. When installing a horizontal puff, it will take on this spacer, and this force will decrease. This farm element performs several functions:

connects rafters,
serves as a support for them,
does not allow the bases of the beams to part.

The puff can be installed at the base of the rafters, then it will act as a floor beam. It can be set higher. With such a device, the tightening is called a crossbar. For large spans, as a rule, it is necessary to complicate the design of trusses, that is, they install not only puffs, but other additional elements.

thrustless

The support of the lower ends of the rafter legs in this system are:

walls, and with their upper ends they are connected to each other by a run, which, in turn, rests on racks or
support frames formed by top and bottom girders, uprights and struts

The elements of the system function like beams, that is, exclusively in bending.

Mounting methods

Thrustless systems. Rafters of this type are installed in such a way that one support turned out to be fixed, and the other - movable, and both of them should be able to rotate freely. In practice, there are three ways to eliminate dangerous loads that affect the walls in this case. The lower end of the rafter leg rests against the Mauerlat. It is hemmed with a bar and fixed using a cut with a tooth. It is also desirable to additionally insure the fastening with wire. The upper part of the beam is mounted on a ridge run. For fasteners use the principle of sliding support. An example is the rafter system of the veranda.

The bottom of the rafter is fixed using a movable joint. To fix the upper part after it is laid on the ridge run, use a bolt, nails, etc. This is the most common option for gable roofs.
Rigid fastening to the run with nails, studs or other fasteners.

In any variant, the following principle is observed: at one end, the rafter leg is fixed on a support that operates on the principle of sliding, allowing rotation, and at the other, on a hinge that allows only rotation.

Spacers. Both supports, unlike non-thrust ones, are fixed. The installation is carried out according to the same construction schemes, only in this case the lower supports are fixed not on sliders, but on a hinge that allows one degree of freedom. Support bars about a meter long can be nailed to the bottom of the rafters, or the support is attached to the Mauerlat on the “tooth”.

For small light roofs, it can be arranged without a Mauerlat, however, it should be noted that in this case the load on the wall is unevenly distributed.

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.

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):

1. Simple gable roof - symmetrical

Simple gable roof - symmetrical 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.

2. Simple asymmetrical gable roof

Simple asymmetric gable roofThe arrangement of one angle of 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.

3. Broken gable roof, with external and / or internal fracture

Broken gable roof, with an external and / or internal break Such a roof construction 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 involves knowledge of the purpose of the main structural elements.

The locations of the elements are shown in the photo.

Elements of the truss system of a gable roof Elements of the gable roof truss system - scheme 2
Elements of the gable roof truss system - scheme 3

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 century of construction. 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.

Roof truss options

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.

Location of the rack depending on the length of the roof

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 (located in the same plane with the rafter pair) are installed, 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.

Calculation of the rafter system 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 attic floor. 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, given the wind load, the entire roof structure can be destroyed.

Wind load on the roof

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.

The scheme for calculating the snow load on the roof

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 sub-rafter elements is needed to create the necessary margin of safety.

3. Calculation of the angle of the roof

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.

Calculation of the angle of the roof

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

5. Calculation of the pitch of the rafters

6. Calculation of the length of the roof rafters

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

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.

Methods for splicing rafters along the length

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;

lying down - 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.

Types of roof system: with 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.

Rafters

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.

Combined view of the truss system

Installation of a gable roof truss system

1. Attaching the Mauerlat to the wall

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

The material was prepared for the site www.moydomik.net

Splicing Mauerlat to each other (straight lock with bolts) 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 timber 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

Mauerlat fastenings with anchorsAnchor bolts. Ideal for monolithic construction.

Mauerlat fastenings with wooden dowelsWooden dowels. Are used for fellings from a log and a bar. But, they are always used with additional fasteners.

Mauerlat fastenings with brackets. Staples.

Mauerlat mounts on studs or fittingsStud or fittings. It is used if the cottage is built of porous materials (aerated concrete, foam concrete).

Mauerlat mounts with a sliding mountSliding mount (hinged). The bundle in this way allows you to ensure the displacement of the rafter legs when the house shrinks.

Mauerlat fastenings with wire Annealed wire (knitting, steel). Used as an additional mount 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.

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.

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

Methods for attaching the rafter leg

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 spacers.

A twine is stretched between the rafter pairs. 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.

Fixing with rafter brackets 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.

Methods for splicing rafter legs

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.).

Installation of the roof ridge without the use of a support beam

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.

Installing the roof ridge by laying on the timber
Installing the roof ridge by laying on the timber

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

Method for making a ridge knot

Cutting method.

Installation of the roof ridge by cutting

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 corrugated board and slate - 440 mm.
under the soft roof we lay a continuous crate.

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

Conclusion

Tags: Roof Gable roof Rafter

The gable truss system is chosen by many owners of residential buildings. This is due to its high practicality and ease of creation. If you carefully study the structure of the gable roof truss system, then the process of its formation can be done by hand. The resulting design is highly reliable and durable, and also guarantees excellent protection of the building from cold and precipitation.

Main elements of the system

The design of the gable roof truss system is considered simple. It consists of a variety of elements made of wooden elements with different lengths, configurations and sections. The main nodes include:

Mauerlat. Represented by a beam with a section in the form of a square. To create it, coniferous wood is usually used. Its dimensions vary from 10 to 15 cm. It is laid along all the load-bearing walls of the building. It is fixed to them with the help of anchors or special rods. If you make and attach it correctly, then it will evenly distribute the load from the rafter legs along all the walls of the structure.
Rafter legs. They are created from a bar with dimensions of 15x10 or 15x5 cm in section. With their proper connection, a roof contour is formed that has the shape of a triangle. It must be strong and reliable in order to withstand heavy loads from rain and wind. Rafter legs must be fixed at a distance of about 1 m from each other.
Sill. Made from square wooden beam, whose cross section is equal to . It is laid horizontally on a load-bearing wall inside the building. Due to it, the load coming from the roof racks is evenly distributed.
Puff. This element is used if a hanging structure is chosen. It is installed on top of the resulting triangle of rafter legs, which ensures its stability.
Racks. To create them, a square beam is used. They are located in vertical position. They bear the load from the ridge, after which it is transferred to the load-bearing wall inside the building.
Struts. The installation of these elements is necessary in order to obtain a special transmission element located between the rafter legs and various load-bearing parts. Due to their reliable connection with a tightening, the creation of a strong structure is guaranteed.
Crate. It is assembled from bars or boards. Installed perpendicular to the legs of the rafters. It provides the transfer of gravity from the roof of the roof to the legs of the rafters. It is advisable to use edged boards to create this element. If you plan to create a coating on the roof of soft roofing materials, for example, shingles, then by all means the crate must be continuous.
Skate. It is represented by the topmost element of the entire roof. Due to it, its two slopes are connected. Its assembly is carried out by connecting the legs of the rafters at the top of the roof. It must be placed in a horizontal position.
Eaves. It protrudes from each wall of the building by about 40 cm. Its installation is due to the need to protect the walls from water flows as a result of precipitation.
Filly. Provides the ability to create a roof overhang. They are used exclusively in a situation where short rafter legs are used, so they are lengthened by fillies.

Important! The step between the legs of the rafters is chosen in accordance with the severity of the roof, since the more weighty it is, the smaller this gap should be.

Thus, the installation of a gable roof truss system is considered quite simple, so it is not difficult to make this design with your own hands.

Types of structures

The rules and features of the installation of this design depend on the selected variety.

Types of gable roof truss system:

All options have their own characteristics, so their characteristics are pre-evaluated. If you plan to install a gable roof truss system with your own hands, then a simple symmetrical design is chosen.

Important! The basis for obtaining the ideal result is competent calculations, and if they are incorrect, the roof will not be reliable and durable, and it will also be dangerous to live in such a house.

How to choose the material to create the system?

When choosing a material, the following rules are taken into account:

rafters are created exclusively from high-quality wood, on which there are no rotten areas, damage, knots or other shortcomings;
edged boards are purchased to form the crate;
all wood should be well treated with antiseptics and fire retardants.

Important! Knots are allowed, but their length cannot be more than 1/3 of the thickness of the timber used.

Calculation rules

To make the gable roof truss system reliable and of high quality, a lot of attention is paid to competent calculations. They should affect all elements of the future design:

Load calculation. Any system is affected by two types of load. The constants will regularly act on the structure, and this includes the weight from the roofing of the roof, battens, thermal insulation material, waterproofing, extensions and finishing materials used for the attic. Typically, this load is 40 kg / m. sq. Variable loads can have different strengths, as they include wind, snow exposure and precipitation intensity. To calculate the load, the wind load of a particular region is multiplied by a special correction factor.
Determining the angle of inclination. A roof with two slopes can have a different angle of inclination, and it is determined by the roofing material used. If a soft roof is mounted, then a slope of 5 to 20 degrees is selected for it, or metal tiles vary from 20 to 45 degrees.
Snow load calculation. In winter, a large amount of snow can accumulate on the roof. In order to avoid any problems with the structure, the frame must withstand these loads. The calculation requires the weight of the snow to be multiplied by the correction factor.
Definition . The gap between these elements is usually chosen in the range from 60 to 100 cm, and the final choice depends on the roof and the weight of the roof.
Definition . To do this, it is recommended to use the standard Pythagorean theorem.
Determination of the section of the rafters. This parameter is influenced by several important factors: roof loads, the type of materials used, the length of the rafter legs, as well as the step between them.

Important! When calculating loads, the possibility of a storm or tornado is additionally taken into account, since if the house is located in a region where such loads can appear, then a margin of safety is made for the roof, read more:.

Types of rafters

Before direct work on creating a gable roof with your own hands, you should make a special plan, which will contain a drawing and layout of the entire structure. This takes into account which rafters will be used, since the following types can be used:

. Suitable for small buildings. Their installation consists in fixing the legs to the bearing wall of the structure, as well as to the ridge run. A feature of the use of these elements is that a bursting force acts on the rafter legs, and puffs are used to reduce this effect. They can be made from wood or metal.
Layered. Suitable for roofs of any shape and size. The layered design is used in conjunction with racks and lying down. The bed is laid parallel to the fixed Mauerlat, so a certain part of the load is transferred to it. This allows you to tilt the legs of the rafters, which are additionally supported by the rack, to each other.
Combined. They are used when using unusual gable roof configurations.

After determining the main design parameters, the calculation begins the right amount material. Then you can proceed to the direct creation of the truss system.

Assembly of the structure

The do-it-yourself truss system of a gable roof is created only after the preliminary formation of drawings and plans. The scheme of future contraction should be clear and correctly calculated. For this, it is recommended to use special computer programs.

Important! In the presence of Money it is allowed to contact specialized construction companies for the correct calculation.

Installation of a gable roof truss system is divided into successive stages:

to the walls of the building. Its installation is carried out along their entire length. If the house is made of logs, then the Mauerlat acts as its upper crown. If cellular concrete or brick is chosen for the building, then it is mounted on top of the load-bearing wall along its entire length. It is required to splice the Mauerlat, for which the bars are sawn at a right angle and connected with bolts. It can be fastened with an offset to the side of the wall or in its center. Laying is carried out on a waterproofing layer, for which roofing material is usually used.
Creation of roof trusses. To do this, it is allowed to install bars on the roof or form a structure on the ground, after which it rises to the roof. The second option is often chosen, since it is difficult to perform work on the roof of the house. But to raise the structure made, you will have to use special equipment. Before connecting the legs of the rafters, the correctness of their size and location is checked.
. The formed pairs rise to the roof, after which they are laid on the Mauerlat. For the competent performance of the work, special cuts are made from the bottom of the legs. The process begins with the ends of the roof, located opposite to each other. To obtain a perfect result, temporary fasteners are used when installing the elements. A rope is pulled between the fixed pairs, making the installation of subsequent elements simplified. All rafter legs are mounted, and the correct step between them is checked. Next, a special skate support is installed. All additional elements used in the rafter system are fixed by cutting and brackets. It is allowed to lengthen the rafter legs if necessary.
Skate installation. It is created with the help of a competent connection on top of all rafter legs. Different methods are used for its formation, and it is allowed to use a support bar for this or you can work without it. If a beam is used, then it is allowed to put a skate on it or use the cutting method.
The rafter system is considered to be done, but in order for it to be strong and reliable, it is necessary to thoroughly fix all the elements, therefore, all temporary fasteners are eliminated, in place of which high-quality products are used to fix all parts of the system.
Lathing installation. This design designed for easy movement on the roof, and also serves as the basis for laying the roof. Its type and parameters depend on the chosen roof. A solid crate is created if a soft roof is selected. has a distance between the boards within 35 cm. For or slate, this parameter is 44 cm.

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 technological features 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 truss system is a load-bearing structure capable of resisting gusts of wind, taking on all external loads and evenly distributing them to the internal supports of the house.

When calculating the rafter structure, the following factors are taken into account:

Roof pitch:
- 2.5-10% - flat roof;
- more than 10% - pitched roof.
Roof loads:
- permanent - total weight 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 rafter 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 trees. conifers(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

Used in industrial construction metal rafters made of rolled steel (I-beam, brand, corners, channel, etc.). 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 rafter 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 outer walls, and their middle parts - on the inner wall or bearing pillar.

Installation of a single roofing system over several spans should include spacer 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 consumption. building materials and load distribution along the perimeter of the building. However, in this case, the attic space will be cold and it will not be possible to equip 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.

truss construction 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:

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

Gable roof: do-it-yourself installation of rafters

Calculation of the angle of inclination and loads

Of course, the calculation of a gable roof 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

You will be able to build safe 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. roofing material choose the best one 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?

Perfect when you've built country cottage personally. 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 the 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 good 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.

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