Making a truss system with your own hands. We make rafters for a gable roof

16.06.2019

Appearance houses and its service life directly depend on how the roof protects the ceiling, how well it will drain water from the basement and from the walls. In our article we will talk about how to make rafters for a house, taking into account all the tips. experienced craftsmen and eliminating the most common mistakes.

Despite the fact that there are many types of roofs, two types are most widely used in individual suburban construction: single-pitched and gable roofs.

Shed roof has the most simple design, which can be mastered even by a person far from construction. But such roofs are mainly used in the construction of auxiliary and outbuildings.

For residential premises, gable or broken (mansard) roofs are most often equipped. Despite some design difficulties, it is quite possible to build such a roof on your own, if you listen to the advice of the masters and do everything step by step, slowly, according to a preliminary project plan.

Hip roofs have a very complex structure and are quite labor-intensive. The arrangement of such roofs should be trusted to professionals. However, hip roofs are the most reliable, they will withstand even especially strong wind loads.

A four-pitched (hipped) roof is used for square buildings. In fact. It is a kind of hip roof.

Of all the above roofs, the most difficult is the cross. It has complex structural elements - grooves (valleys). Such diagonal auxiliary rafters must be installed additionally.

This is a very laborious work that does not tolerate haste and sloppiness. Snow usually accumulates in these places, and the quality of the roof and its reliability depend on how competently this constructive part is performed.

Each of the above types of roofs consists of two main elements: roofs and. The roof is the enclosing part of the roof structure, the rafters are its load-bearing part.

The main types of rafters

Before making rafters, you need to find out them design features and decide on the option of their arrangement.

In roofing construction, there are two types of rafters:

Hanging.
Layered

Hanging - obliquely mounted beams on supports with different heights. The outer walls of the house (single roof) or the outer and inner walls at the same time (gable roof) often act as a support.

It is not at all necessary to fix the rafter legs opposite the slopes in the same plane of the roof. They can be laid alternately on the ridge run.

Such an alternate connection of the rafters in the ridge allows you to equip a construction truss. To do this, you need to tie all the elements of the hanging rafters together into a rigid single structure.

It is important to know: the roof truss must be installed on the extreme two supports. Thus, due to the lack of internal support, the rafter legs will rest against each other in the ridge joint, creating a rather strong horizontal pressure. If the load distribution is incorrectly calculated, then the thrust, being transferred to the walls, can even overturn them.

In order to eliminate such a mistake, experts advise making a puff belt at the bottom of the truss truss. Its main mission is to extinguish the emerging thrust.

What types of truss systems are preferable when building a country house?

There can be no single answer to this question. It all depends on the design of the house, the expected load on the roof and the choice roofing material. So, the on-board ones have a simple device; complex devices and mechanisms are not needed for their assembly.

In contrast, hanging rafters can even be assembled on the ground, but will require additional machinery (such as a truck crane) to put them in place.

Hanging rafters can also be assembled from individual elements right on the house. Further work depends on how to properly install the rafters.

So, it is important to know: you need to make a boardwalk on the attic floor. And in order to temporarily attach the parts, you will need auxiliary jointing and braces made of boards.

Materials for rafters and their connections

Rafters are made from beams or boards. For this, coniferous wood is usually used. The thickness of the board should be at least 40-60 mm.

And all wooden structures should not have flaws in the form of knots and cracks, well dried. Since the logs have big weight, then many roofers do not advise their use.

But the rafters from the boards are convenient to mount and they have light weight. You can even work with such material on your own, without resorting to the help of specialists.

Important: to connect the racks of the truss system with a bed or run, we recommend using notches.

There are three options for assembling the truss system:

with racks
With braces.
With racks and struts at the same time.

Consider how to properly make rafters. Depending on the size of the span between the outer walls, you need to use:

use boards for racks and rafters;
timber 10x10 cm - for the design of the ridge run;
mauerlat and bed can be made from logs, hewn them into two edges or from the same beam (10x10mm).

When making a ridge knot, it is important to nail special clamps made of steel strip with large nails to the run and to the Mauerlat.

You can do without steel clamps, but then you will have to use thick wire twists (with a diameter of 6 mm).

How to make the right rafters for stone or brick house? A continuous mauerlat is laid on brick or stone masonry.

In order to securely fix it, we recommend placing a piece of timber or log (about 50 cm) under each rafter leg. And then, with the help of clamps, fasten to metal hooks, they must first be installed below the Mauerlat by 30 cm.

How to make rafters in cobbled or chopped wooden houses? In wooden buildings, rafters are laid on the upper crown of the wall.

Secure with clamps, which are nailed to the second crown. A rafter plank farm can be equipped with spans (6-8 cm) or with the help of a crossbar.

We equip the structural elements of the fert as follows:

Single tightening with boards, the thickness of which is the same as on the rafters.
For double tightening, boards slightly thinner (more than 40 mm) can be used.
For overlays and crossbars, use boards with a thickness of 30 mm.

Let's look at an equally important question: how to properly assemble the rafters, ensuring the rigidity of the roof in different directions? If the truss truss has the necessary rigidity, then this is quite enough for the longitudinal direction.

But, in order for the roof to be able to withstand wind loads, it is necessary to install a pair of diagonal ties in the transverse direction, and in each of its slopes.

A word of advice: diagonal ties can be arranged using a board 30-40 mm thick. For layered rafters under the ridge and between two neighboring drains, we recommend installing braces. However, in the event that you plan to make a diagonal (oblique) flooring along the crate, then you can not do the braces.

Determine the required section of the rafters

Several factors on which the cross section of the rafters depends:

From the load expected on them (from the weight of the future roof and snow cap).
From what the dimensions of the span.
From the angle of installation and the pitch of the rafters (i.e. from the slope of the roof).

For middle lane It is preferable for Russia to install a gable roof, the slope of which is 30 degrees or more, with a rafter pitch of at least 120 cm.

Consider the dependence of the cross section of the rafters on the length of the rafter leg:

So, with a step of 300 cm, for rafters you can use boards with a section of 8x14; 6x14; 4x18 cm or bars with a section of 10x12 cm.
For a step of 400 cm, boards with a section of 8x18 can be used; 6x20 cm or bars with a section of 10x16 cm.
For a step of 500 cm, you can use boards with a section of 8x22 cm or bars with a section of 10x20 cm.
In those structures where struts were used, the height of the board or beam can be slightly reduced.

Now that you have learned how to properly assemble the rafters, you can safely get to work. To make it easier to lift and move wooden structures, call a friend for help.

After the rafters are installed, you need to do the roofing. Try to plan and carry out such work as quickly as possible in order to protect the truss system from possible wetting. It is best to do this in summer sunny weather.

It is necessary to choose a roofing covering taking into account the slope of the roof and its steepness. It is quite clear that the choice of a roofing coating also depends on the material possibilities, not only during the initial installation of the coating, but also during its subsequent operation.

It is important to consider: the steeper the angle of inclination of the roof, the more money required for its arrangement. This is due to the increase in consumption necessary materials. But, at the same time, steep roofs drain rainwater and snow much better, respectively, they perform their function at 100%, and therefore they will also last much longer without repair.

Despite the fact that at present the market of roofing materials pleases with a variety and a huge choice. Yet a universal roofing material has not yet been invented.

Such that it is both inexpensive and suitable for a variety of weather and climatic conditions was lightweight and durable.

Rafters serve as the basis of the entire roof structure, and their installation is one of the most important tasks in building a house. frame future roof can be manufactured 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 rafter system is a supporting structure that can resist gusts of wind, take on all external loads and evenly distribute them to the internal supports of the house.

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

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

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

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

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

Roof structure elements

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

Materials for the manufacture of rafters

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

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

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

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

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

The choice of truss system: hanging and hinged structures

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

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

A hanging truss system is often used to create an attic or in situations where roof spans are 8-12 m, and additional supports are not provided.

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

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

Features of the arrangement of rafters on different roofs

Gable roof

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- sloping roofs to minimize the 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 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.

Create hipped roof it is possible without a rack, but at the same time, the design must be strengthened with additional modules - racks with puffs.

hip roof

The traditional design of the hip roof assumes the presence of slanting rafters (diagonal) directed to the corners of the building. The angle of inclination of the slope of such a roof does not exceed 40 °. Diagonal runs are usually done with reinforcement, since they account for a significant part of the load. Such elements are made from a double board and a durable beam.

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

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

broken roof

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

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

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

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

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

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

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

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

Installation of Mauerlat and rafters

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

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

Installation of rafters: video

Ways to connect the elements of the truss structure: video

The rafter system is the supporting frame for the roof. That is why it must be reliable, since the durability of the entire structure directly depends on the quality of the material from which the elements of the system are made, and the professionalism of its assembly.

it is quite possible to manufacture and install, having a master nearby who has already done this more than once. Without experience in this work and a reliable adviser, it is dangerous to take it yourself - it is better to entrust this event to a team of qualified craftsmen. However, if you nevertheless decide to try your hand, then you need to approach all the details of the system with all responsibility and caution, since the work is not only difficult, but also quite dangerous.

In order for the entire roof system of the house to last a long time, dried softwood is selected for the manufacture of its elements. For rafters, a beam is needed, having a size of 100 ÷ 150 × 50 ÷ 60 mm.

Coniferous wood is light in weight, which is favorable for the entire construction of the house, since a heavy rafter system, creating a lot of pressure on the walls, can lead to damage and destruction.

Another advantage of coniferous material for the construction of the foundation for the roof is a high percentage of cm of leafiness in its structure, which means an increased ability to withstand atmospheric moisture.

For the manufacture of elements of the truss system, it must meet certain requirements that directly affect the durability of the entire structure:

Wood for mounting the rafter system must be aged, which will eliminate the risk of its deformation in the structure.
The moisture content of wood should be no more than 2-2.5%.
If a hanging rafter system is arranged, then for the puffs and the rafters themselves, wood of only the first grade must be taken.
When building a layered system, the second grade of material is also suitable.
For retaining elements - racks and struts, you can also use the third grade of wood, however, while trying to choose raw materials, on which the minimum number of knots.
The exact thickness of the blanks is selected depending on the weight of the selected roofing material and on the weather conditions in the region. This is especially true for the maximum thickness of the snow cover in winter period. For example, for the middle zone of Russian regions, it is necessary to calculate the load on 1 sq..m . roofs in 180÷200 kg.
In addition, the parameters of the rafter legs depend on the overall dimensions of the truss system and its slope.
Before installing the system, the wood must be subjected to anti-fungal and fire-fighting treatment.

When installing a structure, you need to know and types of loads that the entire roof system is exposed - they are also taken into account when choosing the parameters of the rafters and installing the structure.

Live loads are the weight of a person at repair work roofs, snow cover in winter and the strength of gusts of wind.
Seismic effects are special types of loads if the structure is located in seismically hazardous regions.

General design of the truss system

The most common the truss system has the shape of a triangle and is intended for arrangement. It includes several triangular elements, consisting of two rafter legs and auxiliary supports, and couplers. Each such triangular structure is called a rafter. The triangular elements of the system are located at a certain distance from each other, and most often it is from 50 to 80 cm.

This form has become traditional, as it creates better rigidity and reliability of the structure. It can end at the level of the walls or be continued for the installation of overhangs, which can be 40 centimeters or more long. Sometimes the rafters ending on the walls are built up with additional bars - “fillies”.

So, as mentioned above, the rafters are one triangular section, which includes:

Two rafter legs connected on a ridge beam, or without its use, directly to one another.
Braces or rafter legs are struts that support the rafter leg and lighten the load that falls on it. They rest against the bed and are fixed to it.
Racks or vertical supports, consisting of bars. They, like the spacers, support the rafter leg, but closer to the center of the triangle. The rack is installed on the bed.
A crossbar is a board that holds two rafter legs together.
The fight is two crossbars fixed on both sides of the rafter leg. It performs the same task as the crossbar - it gives structural rigidity.
Grandma is vertical bar ok, which is retaining and is installed in the middle of the triangle, resting against the floor beam and supporting the ridge. This part is used in hanging rafter systems.
Run - they connect individual rafters in common system. They are parallel to the wall.
Puffs are floor beams that connect the rafter legs, closing the rafter triangle.
- a powerful bar installed at the upper end of the wall structure, to which elements of the truss system are subsequently attached.

There are three types of truss systems - these are layered, hanging and combined, i.e. including elements of both one and the other.

Hanging system

The hanging rafter system is used to cover buildings without internal main walls. The rafter legs are laid on the Mauerlat, fixed on the load-bearing walls.

Since a large one falls on such a system, which is transferred to load-bearing walls, the following additional elements are used to relieve this stress:

A puff that simultaneously performs the role of a floor beam. It can be used with a span of up to 6 meters. If the span is larger, then it is raised higher along the rafter leg, and in the lower part the triangle is also closed with a floor beam.
Headstock supporting the ridge, it is mandatory to install if the span between the bearing walls is more than eight meters.
Struts extending from the headstock at an angle and supporting the rafter legs.
Support that strengthens the rafter leg.
A ridge beam is required in this system.

All elements are attached to each other metal corners, staples or twisted with screws.

Layered system

The layered system is more stable and reliable, thanks to additional supports in the form of capital partitions inside the building. Their presence makes it possible to make an additional room in the attic.

When making such a decision, the racks in the truss system are installed closer to the load-bearing walls, freeing up space.

In this system, the rafter legs are installed on the Mauerlat, which is fixed to the side load-bearing walls. For the reliability of the installation, special grooves are cut in the rafter legs, and the elements are fastened together with staples.

A ridge beam in this system is desirable if a large span is formed between the load-bearing walls, and it is planned to arrange a living space in the attic. The same applies to puffs, which in this case are fixed at the level of the ceiling of the future room.

You also need to know that the mauerlat must be very securely fixed to the wall with pins that extend 350 ÷ 400 mm deep into the wall, since it receives a large weight and dynamic load from the entire rafter system.

If it is assumed that the main walls of the building can shrink slightly, then the lower parts of the rafters are attached to the Mauerlat with sliding fasteners, which allow the element to take the desired position without harming either the walls or the entire truss system.

Video: gable roof truss system

Installation of the truss structure

Having prepared suitable material and having a roof design project, you can proceed with its installation.

Gable roof

Mauerlat bars are fixed on the load-bearing walls on a pre-laid waterproofing material - ruberoid, and they mark the installation of rafters. It is very important to make the markings on both sides of the installation in the same way, otherwise the rafters will be skewed.

The first rafters are adjusted and rigidly fastened directly at a height so as not to make mistakes in fastenings and in samples for installation on.
Then, they are lowered down, and all the other rafters are made according to the first sample. On the ground, it is much easier and safer to fit all structural elements to each other and make reliable fastenings.
When sawing the bars under the rafters, it is necessary to leave a small margin, i.e. make them a little longer than required so that you can fit them in place.
To make it easier to navigate, exposing the first rafters, they take a beam, the length of which is equal to the distance between the outer edges of the walls - this will be the base or hypotenuse of the future triangle.
The middle of the bar is determined, and a perpendicular board is temporarily nailed to it, having a height from the front wall of the structure to skate - peaks equilateral triangle.
Then, laid out and fixed sides - legs triangles, they are rafter legs.

If a hanging rafter system is selected, then the puffs are immediately marked and fixed.
If it is supposed to install additional fasteners, then they are fixed already in place, after installing the rafters on the roof.
Further, the first rafters are first raised and temporarily installed. On each of them, places are marked where rectangular selections will be made to fix them on the Mauerlat.
Then, the rafters are lowered down again, and grooves are cut out on them, having a right angle.

For the first pair, taking it as a sample, the same grooves are measured and cut out on the remaining rafters.
Further, two triangles rise to the walls, which are installed at the beginning and end of the future one. If a ridge beam is provided, then both installed parts are immediately connected to them.

Video: how the rafters are attached to the Mauerlat

Cords are stretched along each slope between the already mounted rafters, which will also serve as guidelines for aligning the rest of the structure.
The first installed rafters are immediately reinforced with racks, struts and other elements of the system that give rigidity and reliability to the structure.
Further, the remaining rafter pairs are raised and installed.
If necessary, they are interconnected by runs and beds.
When installing the rafter system, all its elements are temporarily fixed, since it is possible that some of them will have to be adjusted and reinstalled later. They are thoroughly fixed only after reconciliation of the entire system. Then corners, brackets, and, if necessary, sliding elements are used for fastenings. Self-tapping screws, nails, bolts, staples and studs are used at different joints.

If necessary, the rafters can be extended with "fillies"

After the system is basically installed, the rafters can “filly” on overhangs - this is done so that the walls of the building are as well as possible covered from moisture getting on them during rain.
The next stage of work is the device of the crate on top of the rafters. The thickness and width of the boards for this part of the structure are selected taking into account the installation technology of the selected roofing material - this will depend on the width, weight and length of its sheets.

Video: installation of a gable roof truss system

Single slope systems

It is generally accepted that a shed system is used only when constructing the roof of garages, sheds, gazebos and other non-residential buildings, but this is not at all the case. Such a roof also serves perfectly to cover residential buildings, and under it you can even arrange an additional warm room if you correctly calculate the slope of the structure.

A single-pitched system can be considered as half of a gable roof, but with some deviations. For example, if when installing a gable roof, the gable part is the width of the building, then with a single-pitched roof, its length.

The pediment can be raised from brick or wooden beams and boards. Its height will depend on the selected roof slope. The gable of the roof is raised high if an additional room is arranged under it.

The rafters in this system are easier to lay, but if the distance between the walls is large enough, then it is still necessary to install additional supporting elements for rigidity.

To correctly determine the desired slope angle, you need to rely on the following factors:

The thickness of the snow cover in winter and the average amount of precipitation in other seasons.
Weight roofing, which is planned to cover the truss system.
Temporary loads, in the form of gusts of wind.

The angle of this type of roof can vary from 5 to 45, and sometimes there are buildings with an angle of even 60 degrees.

Installation of a single-slope version is carried out on site, i.e. at a height, since the pediment and rear walls of the building serve as supports for the rafters.

If the slope of the roof in a one-story mansion is not too large, then the rafters can be extended forward from the front or back of the house. This is done in order to arrange a veranda or terrace under the roof.

Attic systems

The most complex in execution are mansard roof systems

If it is immediately laid down in the project to make the attic of the house residential, then you can choose one of two roof structures. The choice will depend on the desired attic area and ceiling height. It can be a gable with a high ridge or a broken mansard roof.

Gable roof

To arrange under a gable roof additional room, the space must be free from various additional fasteners. Therefore, you will have to get by with a minimum number of them.

Mandatory in this design will be racks and puffs - they will also perform the functions of the crate, on which it will be attached finishing material walls and ceiling of the building.

But in this case, it is very important to use massive bars for the floor beams, which will calmly withstand the weight of the truss system with insulation and roofing material, plus the entire load given by the pieces of furniture that will be installed in the room. In addition, it is necessary to mount the bars of the floor beams at a small distance from each other, which should not exceed 50 ÷ 60 cm, but in order for the walls of the building to withstand the entire load without problems, they must be quite massive and strong.

Installation of the system takes place in the same sequence as a gable roof.

Attic "broken" design

The mansard roof structure of the house is more complex than the usual gable, but its advantage is that living space, which is obtained as a result of its installation, will be much larger, and the ceiling will be higher.

An approximate diagram of the attic "broken" system

This type of roof is called broken, as the system consists of two parts, in each of which the rafters are located at a different angle.

The side rafters can be positioned at an angle of 30 or 45 degrees from the vertical - this is the most common installation options.

The top is fixed at an angle that can vary from 5 to 30 degrees from the horizon.

In the attic structure, both rafter systems can be used. It is preferable to arrange the lower rafters according to a layered system, but if there are no capital partitions in the building, then a hanging one can also be used. In the latter case, beams attic floor, as well as rafters, should be installed at a distance of no more than 50-60 cm from each other. It should be noted that the walls must be well fortified, since the load on them will be quite serious, much more significant than with a gable roof.

The beginning of the construction of the lower truss system begins with the installation of racks, fixed with strapping from above, and from below - by floor beams. The distance between the rack systems will be the width of the room, and their height determines the height of the room.

Start of installation - installation of two rows of racks

This frame will determine the placement of the remaining elements of the system.
Next, you need to find the middle of the distance between the rows of racks, and this will determine location in the upper part of the attic. In this place, a vertical bar is installed, the same height as the rack system.

Then, side rafters are installed, they are fixed to the rack strapping and a beam overlap, thus, triangles are obtained in which the rack and beam overlaps form a right angle.
When all the side elements are installed, proceed to the installation of floor beams, they are also attached to the strapping bar and the end of the side rafter. A diagram of this bundle is shown in the first figure in this section.
Further, the floor beams are connected to each other by a horizontal rail, which is stuffed on top of them, in the middle of the structure.
Ridge rafters are installed, which are supported by struts. They are attached to the rail connecting the floor beams.

On the ridge, the rafter legs can be fixed to the ridge board or connected by a metal or wooden plate to each other
Sometimes, for structural rigidity, a supporting headstock is installed between the ridge and the floor beam.

The crate of the gable walls is made with openings for windows. If the entrance is from the street, then on one of the gables, in addition, an opening for the door is provided.

Further, if necessary, the entire truss system is sheathed with sheathing or plywood, if a soft roof, for example, flexible tiles, is chosen as the roofing material.

Video: an example of installing a truss attic system

To equip the truss system is not at all simply, and you cannot cope with this work alone - you will need at least two assistants. It is desirable that at least one of the invited masters has some experience in this field of construction.

When building a truss system, to ensure the reliability of the structure, it is important to monitor every detail. Particular attention is paid to the attachment point of the rafter to the Mauerlat. It is in this place that the main part of the load is transferred to the load-bearing walls. At the same time, it is important not only how to fix what to use, but also washed down the accuracy. After all, if the board is not fully supported, then it can break and lead to the collapse of the roof. In the article, we will consider how to cut down the rafters and what methods exist for this.

Varieties of fastening rafters

Depending on the design solution, the presence of internal walls and the calculated load, various types of fastening are used. Each of them implies its own version of the preparation of rafters for docking with the Mauerlat. The three main attachment methods are listed below:

hard;
layered;
sliding.

We will not consider the latter option, since when using it, it will not be necessary to make cuts. It is usually used when constructing a roof on houses made of timber. It is most suitable, as wooden walls shrink over time. Because of this, the truss system can change the geometry and leaks will appear.

In other options, you will have to make accurate cuts. You will need accurate measuring instruments, a construction pencil and an electric or chainsaw.

The strength of the roof depends not only on how the cuts were made correctly. Consider the following tips:

For rafters choose quality materials, because, even if you make accurate cuts, the bar may not withstand the load. You can’t save here, because this part takes all the load on itself.
Mounting points with Mauerlat must be free of wood defects, such as knots. Although they are stronger than wood, turbulences form around them, which break at the slightest load.
When installing a roof, do not hesitate to ask for help, as this is a dangerous and responsible business.

A well-made junction of the rafter leg and the Mauerlat guarantees a long service life of the structure.

Cutting out a seat

It is important to understand that it is impossible to perform a perfect gash on a construction site. The reasons may be different: lack of high-precision tools, uneven position of the Mauerlat, uncomfortable position, and so on. Therefore, relative to the design value, the slope angle of the ramp may change. Here, the main thing is to maintain a single line of position of the rafters.

The easiest way to make the same washed down on the rafters is to use a template. True, this option is not suitable in all cases, so often the roofs are uneven. Then you have to calculate the angle and place of cutting on each rafter individually.

For the basis of the template, take a piece of board, a piece of fiberboard or plywood, even thick cardboard will do. On the workpiece, draw a line from the bottom edge at a distance of no more than a third of the width of the rafter. The same line must be drawn on all the bars that you plan to cut. The fact is that it is not recommended to cut deeper because of the loss of strength. Next, mark the points at which the rafter will be adjacent to the Mauerlat, make a perpendicular line relative to the previous line.

Now let's move on to making a template by determining the angles of the vertical and horizontal parts of the notch. To do this, attach the workpiece to the end of the Mauerlat, keeping the slope of the future roof. Opposite the corner should be the intersection point of the lines that were made before. Draw the lines of the triangle and cut out the resulting template.

Before transferring the markup to the rafters, check the accuracy of the finished product. Walk along the roof and check the degree of abutment along the entire length of the Mauerlat. Make adjustments if necessary, but don't expect ideal option. Drops of 2-3 mm are acceptable.

The maximum concentration is important so as not to go beyond the outlined boundaries. If you are not confident in your own abilities, then use hand tool. So you reduce the percentage of marriage and the time for rework.

The second cut is made with an ax, as the power saw can be stuck. It also requires skill and strength. It is important to make sure that the ax is quite sharp, then the case will be argued better and chips can be avoided.

Finally, check the resulting file with the template and make adjustments if necessary. After that, you can install the finished rafter leg or make seats on the rest of the details.

Cutting for a direct joint with Mauerlat

An easier option is to make a butt joint. To do this, you need to determine the location of the cut and the angle of its inclination. For this purpose, two options can be applied: theoretical and practical.

For the theoretical method, you need to be well versed in geometry and calculate the desired angle on paper. Divide the distance from the ridge to the eaves by the length of the rafter. So, you will get the cosine of the desired angle. In order to transfer it to the workpiece, you can use either miter saw, or a special square.

If you don't have a special tool on hand, make a simple template. Take a durable material, such as chipboard. On the sheet, mark 500 mm along the bottom edge, then determine the tangent of the required angle and multiply by the measured length. So you get the other side right triangle. After marking all the borders and cutting out the workpiece, get the desired angle. The sawn parts can be mounted immediately or wait until the whole set is made.

In practice, you can easily mark up a separate rafter by attaching it to the design position. To do this, set the beam so that its lower part is flush with the Mauerlat. Draw a horizontal line from the corner to the bottom of the rafter, it should be strictly parallel to the wall. Now you can safely saw off with any tool at hand and install the part. The rest will serve as a template for the remaining rafters only if the base is even.

Knowledge of geometry helps not only in determining the angle of the washed down rafter leg, but also in determining the height of the roof, the length of individual elements, and so on.

J. Carroll (Canada)

BUILD ONE

CONSTRUCTION OF THE ROOF

Building without help is not easy. There you need to support, but here - to squeeze. At the same time, only a magician can be in two or even three places at once. Don't break? The author of this article proves by his example that one person can also build a house. smart technology, special devices allow you to do this very efficiently. Today he talks about how he erected a roof alone.

The construction of the roof is the most responsible and difficult stage of construction. You have to work at a height, and any kind of fitting is practically impossible here. So, you need to calculate everything well and think over the design so that the installation of the roof becomes less time-consuming.

Work traditionally begins with the preparation of rafters. To do this, I use a template made for specific roof parameters (the angle of inclination of the slopes and dimensions buildings). This device (Fig. 1) allows not only to mark typical cuts on workpieces, but can also serve as a guide when working with a circular saw. The sequence of marking the rafters using a template is shown in fig. 2.

Rice. 1. Template for rafters. Attach with screws

Guide rails are nailed on both sides of the template

with rafters, I begin work with the installation of a ridge run. I assemble support posts for it from two boards. This not only increases the rigidity of the supports, but also simplifies further work for installation. Since the boards are knocked down with an offset in height, the ridge beam is securely fixed in the “saddles” of the uprights. I raise the run in stages, and the assistant is replaced by two pairs of L-shaped brackets and clamps (Fig. 4).

I pull the first pair of brackets to the racks at a height of about 1 m from the floor and lay the run on them. So that it does not jump off the shelf, I temporarily fix its free end with another clamp. Then I install the second pair of brackets and alternately raise the ends of the run to new level. I repeat the process until the bar "sits on saddles".

Having marked the first rafter, then I use a technological rail with control points C, D, E and F transferred to it (Fig. 3). For each subsequent rafter, I first saw the ridge part according to the template, then I measure the distance corresponding to the length of the slope, and in the end I apply a technological rail to point C and transfer points D, E and F to the workpiece. It remains only to draw desired lines according to the template, and the markup is complete.

However, the most time-consuming operations are associated with the installation of the supporting structure of the roof. For pitched roofs

54 Pro Tips #109

Rice. 2. Marking the rafters.

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Step 1. Marking the ridge part of the rafter Attach a template and draw a cut line with a pencil.

Step 2. Marking the length of the slope. Set aside from the bottom point of the ridge cut the distance corresponding to the selected length L of the slope and get point C. Attach the template and draw a line of the horizontal shelf of the tooth with a pencil.

Step 3. Marking the tooth. From point C, set aside on the resulting line the distance corresponding to the thickness S of the beam

the upper strapping of the wall, and then, using the template, draw a line parallel to the “ridge” cut through the obtained point A and get point D on the bottom edge of the workpiece. Triangle ACD - rafter tooth.

Cross-sectional template of the frontal board B

Step 4. Marking the overhang of the rafter. At a distance corresponding to the thickness of the outer skin of the wall, draw a line parallel to segment AD and get point E on the bottom edge of the workpiece. Without moving the template, draw a line along the other side of the triangle - this is the lower edge of the rafter overhang. Before lowering the perpendicular to it from the upper edge of the workpiece and getting point B, use the cross-sectional template of the frontal board for sewing the overhangs of the rafters - it must “fit” inside the contour of the workpiece.

One of the difficult moments in the construction of a frame house, which some novice builders stop before, is the question of how to properly make cutouts in the rafters of a house. If you carefully study the material, the experience of experienced builders, it turns out that making them is quite simple.
So that the cutouts in the rafters do not confuse you, I am writing this article.

When writing the article, I relied on an experienced American carpenter. I simply translated some parts of the article, I wrote the technical part in the likeness, but with my own dimensions, in the metric system and without a construction calculator (not everyone has a calculator), plus I slightly changed the counting scheme (because, again, not everyone has a calculator ). For Russian realities this article has been updated.
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Rafter system of a frame house

When I was a young carpenter (or should I say a carpenter's assistant), I admired the skill of roof carpenters. They effortlessly made complex cuts in the rafters frame house knowing only the dimensions of the roof. This puzzled me.
In those years, I tried to repeat their actions, but I failed over and over again. Then the senior carpenter took me with him to one of the roofs and helped me mark and cut the truss system with the help of a carpenter's square and the roofer's "Bible" (there is such a very popular book in America, you can buy it on Amazon, Larry Hawn used just such a book in his film - translator's note). This experience inspired me to master the art of making proper cuts in the rafters of frame houses. I can’t say that I have become a master of this business, but I have come a long way and figured out a little how to do it right.

For more comfortable calculations, you will need a construction calculator or a special smartphone application.

Let's move on to measurements

(I'll show you how to calculate everything manually, without a calculator - approx. translator).

Here are the dimensions of the truss system we need: rafter angle(Pitch) climb(Rise) mileage(Run) and diagonal(Diagonal). if you known dimensions any two of these four dimensions, you can easily find all the others.

See the video for more details:

(for those who understand English - approx. translator)

Look at our roof model (picture above), initially we need to know the dimensions of two of its elements: building width And ridge board thickness.

The width of the building, for example, will be 8.8 meters. (8.75 meters and sheathing with an inch on each side of the house 0.05m):

Each rafter stands on its own half of the building and is joined to each other on a ridge board. Therefore, from the total width of the building you need to subtract ridge board thickness, otherwise you will make a mistake when calculating the length of the rafter. Let's take its thickness of 50 mm.

We consider the general building width without ridge board: 8.8 meters - 0.05 meters (50 mm) = 8.75 m

Now we need to divide the result by 2 to get "mileage» (Run) of each rafter.
We believe "mileage" each rafter: 8.75m/2 = 4.375m.

Now we need one more element that we know in advance, this is the angle of the roof slope. In our case, let it be 6 to 12 (26.5 degrees- approx. translator).

Since our roof has a slope 6/12 , which means climb we have in two times less, how mileage(because 6 is 2 times less than 12).
We believe climb: 4,375/2 = 2.187m.(half a millimeter rounded)

We believe diagonal:
Run("2) + Rise("2) = Diagonal("2) ("2) - I marked "squared".
19.1406 + 4.7851 = Diagonal("2)
Diagonal = Square root out of 23.9257
Diagonal = 4,891 = 4 meters 89 cm 1mm

Rafter template.

The next step after the calculations - making a template for rafters. To do this, you need to screw the bosses to your square (it’s more convenient, but you can do without it) at 6 and 12 inches (or 15 and 30 cm in the metric system).

Now I apply the square to the side of the board along its width and begin to mark the place of the cut at the top of the rafter (in junction with the ridge board- approx. translator). Please note that most cuts in frame housing construction are done in this way: the board is cut along the length on the thin side, and in the width in a horizontal position.

I make this saw at the top of a rafter with circular saw(on video) before tagging cutout at the bottom of the rafter(so-called "bird's beak" or incoming corner or notch - approx. translator). This is convenient because I can hook the end of the tape measure to the saw at the top and mark the distance on the rafter to the "bird's beak" alone (see the picture below)

Now from the top point of this line we measure the "diagonal" 4 meters 89 cm 1mm.

Then, using a regular carpenter's square (some carpenters prefer the Swanson protractor square, you can read about it on the forum - approx. translator), I draw a parallel line to the first saw across the rafter. This line represents the plumb line (i.e., parallel to the wall and perpendicular to the floor of the frame house) on the rafter at the edge of the building.

How to draw such a line on the Swanson alternative square, the following short video will show:

I personally love my Swanson square very much, it is mine faithful assistant in construction from the very first days.

So, "bird's beak" starts from this line. If you are building and you have clear dimensions of rafters and cuts (project), you must choose at this stage the size of the horizontal cutout, the plane of the rafter, which lies on the ceiling (see the bottom photo on the bottom left). Canadian codes require this saw to be at least 38 mm.

The horizontal dimension should be such that the rafter is not greatly weakened, i.e. the cut did not go further than a third of the board (see figure below).

According to the author, this is the most fast way mark this cut (pictured above). To do this, you need to turn the square 90 degrees to the previous saw and press the bosses to the board, while slowly leading the square towards the top of the rafters, until the required distance from the drawn line and the angle of the board in the direction of the square (in the original was 4 inches).
There is another method (pictured below).
We apply the square to the drawn line and move the square along the vertical line until the desired mark of the horizontal scale (110-120 mm) touches the edge of the board.

Let's look at our case.

Let's take for example that we have rafters from a board 200×50mm. For her, with a roof slope angle of 6 to 12, it will be safe to make a horizontal cut 120 mm. In this case, vertically taken away from the board 60mm(since with such a slope we always have a vertical size 2 times smaller than the horizontal one, remember?) and the rafter will definitely not be weakened.
And here are interesting estimates for cuts at different angles and different board widths (according to one authoritative frame builder from the forum):

We consider the "rise" in reality.

Yes, we already have the "rise" size and it is equal to 2.1875 meters. But let's look at our scheme of the truss system. Obviously, our size is not the same as the board that supports the skate (even if only temporarily).

First we need to add to our "rise" the so-called H.A.P., which is equal to the size remaining vertically above the wall trim under the bottom of the rafters, where we made a vertical cut (pictured above).

We believe our H.A.P: 223.6mm (full width of the board at 26.57 degrees) subtract 60mm (our vertical cutout) = 163 mm.

Now to our rise (2.1875 meters) add H.A.P ( 0.1635 m), it turns out 2.35 m.

We ended up at the highest point of convergence of the rafters at the ridge board. But we don't need her. Now we finally get the height of the desired board for the ridge board.

Height skate boards: 2.35 m subtract the height of the ridge board 200 mm = 2.15 m, i.e. 2 m 15 cm.

Find the full length of the rafters.

After all this mess, I would like to know the length of the TOTAL rafter, i.e. with eaves. Everything is simple here.

For example, we need overhang 80 cm, this means that with a roof of 6 to 12, the overhang lowers down by ½ of the length of the overhang, i.e. 0.4 meters.

We believe overhang diagonal= 0.16 (0.4 squared) + 0.64 (0.8 squared) = 89.5 cm

Total full length of each rafter with overhang = 4 meters 89 cm 1mm + 89 cm 5 mm = 5 meters 78 cm 6 mm.

A small bonus to the text.
square Swanson deserves a separate video (below). And for those who are imbued with it and decide to buy it, be sure to have at hand a translation of the book that comes with it on sale in English. language.

So, I hope, after reading this article, it has become much clearer to you how to make cutouts in the rafters of your frame house. If you have any more questions, get in touch.

How the site can help you

1. Make it convenient and understandable for you (or help in designing a frame house).

4. Bring you from Belarus

5. 1. Consult on any issue of frame housing construction. 1 hour - 1000 rubles(or 2 weeks of answers in text format also for 1000 rubles)

You can contact me via email or phone +79200221811

The truss system is the basis of the roof, the reliability and strength of the roof, its ability to withstand precipitation and wind depends on it. The design of the truss system is determined by the shape of the roof and the features of the layout of the house, as well as the materials used. A do-it-yourself truss system is usually made of wood, but other materials, such as a metal profile, can also be used.

Types of rafters and their application

The choice of a truss system is a crucial step that requires knowledge of the design of each type of roof. Rafters can be:

Laminated rafters based on a ridge run and Mauerlat. They are used in the construction of a single-pitched, simple gable roof, as well as one of the elements of a hip and sloping mansard roof.
Sliding rafters - a type of layered rafters used for wooden buildings that give a lot of shrinkage. Their difference is the sliding fastening of the rafters to the Mauerlat, which allows you to compensate for the shrinkage of the walls without deformation of the roof.
Hanging rafters - a system of rafters tied with crossbars or puffs, usually used in the construction of a simple gable roof, as well as the upper rafters of a mansard roof. In the hanging rafter system, there is no ridge run, and in the upper part the symmetrical rafter legs rest directly on each other.
Sloping rafters, otherwise called angular or diagonal. They are used to make a three-pitched or four-pitched roof, as well as for roofs with complex geometry.

Elements of the truss system

Any rafters are designed to distribute and transfer the load of the roof to the walls of the house. The main elements on which the rafters rely are:

Mauerlat - a beam fixed on the upper plane of the walls around the perimeter of the whole house;
Beds - support bars laid on internal load-bearing partitions or columns;
Beams of the ceiling of the upper floor;
Racks and supports;
Runs - horizontal support elements laid along the roof axis on racks.

The truss truss consists of the following elements:

Rafter legs - boards or beams that form the contour of the roof and are laid with a certain step;
Puffs or crossbars - horizontal elements that pull paired rafter legs together;
Struts - supports set at an angle and supporting the rafter legs;
Filly - boards fixed at the lower end of the rafters and forming roof overhangs;

Narozhniki - short rafters resting on diagonal rafters in a hip roof.

All these elements in private construction are usually made of wood - timber or boards of coniferous species, dried in a natural way. The tree is impregnated with an antiseptic, which allows you to extend its service life. The thickness and section of the elements is determined by calculation.

Laminated rafter technology

Before construction begins, it is necessary to sketch the roof and calculate its dimensions. The cross section and pitch of the rafters, as well as the need to install additional supports and struts, are also determined by calculation.
Support elements are laid and exposed: mauerlat, beds and floor beams, racks, ridge and intermediate runs. These operations are described in detail in the articles on different types roofs:
Make a rafter template. To do this, take a board with a width corresponding to the estimated length of the rafters, with the same width, but with a smaller thickness - it is lighter and easier to fit exactly in place. The board is applied to the installation site of the extreme rafter with one end to the ridge run, the other to the Mauerlat.
At the top of the template mark the top gash. The shape of the cut should be such that the board lies on the ridge run and at the same time fits snugly against the opposite rafter. The depth of the cut should be no more than 1/3 of the width of the board.
After sawing out the upper cut, the template is once again applied in place and the lower cut is marked out - it should rest on the Mauerlat, without leaving large gaps. The end of the template is filed at an angle so that the cut is in a vertical plane.
The resulting template is applied at the installation site of all rafter legs, checking whether it will be necessary to fit in place. If the template fits perfectly (which rarely happens), you can immediately make the required number of rafter legs. If adjustment of the lower notch is needed, then only the upper part of each rafter is cut out according to the templates, and the lower notch is done in place each time.
The rafters are placed with the established step calculation. Usually it is from 50 to 120 cm and depends on the type of roofing, namely on its severity, and on the expected snow load. The heaviest coatings are slate and ceramic tiles, but they are rarely used today. More often, the choice is made in favor of more modern, light and reliable materials: metal tiles, ondulin, soft roof. For them, the pitch of the rafters can be chosen about 100 cm without performing complex calculations.
First, rafters are installed from the side of the gables. The rafter leg is supported on the ridge run and the Mauerlat and fixed on two nails 100-150 mm in each attachment point. Having installed the rafter pair, they additionally fasten it: in the upper part with the help of metal plates and self-tapping screws on one side and corners with a stiffener on the other, in the lower part - with brackets or also on the corners.
After installing the rafters from both gables of the roof, a twine is pulled between them and the rest of the rafters are aligned along it. Rafters are fastened in the same way.
Install struts, if required by the results of the calculation. The struts are made from the same material as the rafters. A board of suitable length is applied at the desired angle to the rafter and the bottom cut is marked. It is important to consider what the brace will rely on: on the floor beam or on the bed, the shape of the lower gash depends on this. After completing the lower cut, the brace is put in place and the cut line along the rafters is marked. The prepared brace is placed at a distance between the beams and rafters and secured with metal plates or corners.

Roof strut installation

Technology for the implementation of hip diagonal rafters

Since the rafters for the hip roof are installed diagonally, conventional ways their mounts don't fit. In addition, the load on diagonal rafters is much higher than on layered or hanging ones, so the material for their implementation must have a larger cross section. You can use a beam with a thickness of 100 mm or more, but practice shows that it is more convenient to make these rafters from two folded and fastened boards of standard thickness.
The diagonal rafters are supported by the upper end on the racks, the lower end - on the Mauerlat bars converging at right angles. They are marked in place, and their main feature is that the cuts are not made perpendicular to the plane of the board, but at an angle of 45 degrees. When making rafters from spliced boards, first one side is performed with oblique cuts, then the second, in a mirror image.
Boards are pulled together by screws, nails or studs. The hip rafters are fixed with overlays and self-tapping screws.

A video will help you better understand the basic techniques for building a truss system with your own hands.

When doing any rafter system with your own hands, it is important to carefully secure all knots and connections and remember that the roof is the main protection of your house from bad weather. Therefore, it is important not only to make a high-quality frame, but also to choose the right one, for example, corrugated board, and lay it correctly.