Gable roof nodes. Rafter system: types and installation for different forms of pitched roofs. Video: Roof rafter system, what you need to know for proper design

Roof construction is one of the most critical stages of construction. The durability of the building itself and the level of comfort of living in it directly depend on the reliability of the "umbrella" from above, on its resistance to precipitation and any external influences.

Of all the variety of roof structures, the gable can be attributed to the most popular, simply due to the relative simplicity of its construction. However, behind this "simplicity" lies a lot of different nuances, the need for certain calculations and adherence to technological rules. Nevertheless, this publication has the main task: to show that installing the rafters of a gable roof with your own hands is a completely doable task, even for a novice builder.

Let's go through all the stages of the process of installing rafters for such a roof together, from the basics of preliminary design to an example of practical implementation.

General structure of a gable roof

Basic concepts

Structural elements of the gable roof truss system

Let's make a reservation right away that this diagram, of course, cannot reflect the entire possible variety of designs, but the main details and nodes on it are shown quite clearly.

1 - Mauerlat. This is a board or timber that is rigidly attached to the upper end of the external load-bearing walls of the building. Its purpose is to evenly distribute the load from the entire roof system to the walls of the house, to create conditions for reliable fastening of the rafter legs at their lowest point of support.

2 - rafter legs installed in pairs. They become the main bearing parts of the entire roof system - it is the rafters that set the steepness of the slopes, will be the basis for fastening the battens, roofing, and if the roof is planned to be insulated, then also the entire thermal insulation "pie".

For the manufacture of rafter legs, high-quality boards or timber are used, you can also use round timber. About the cross-section of lumber, which will be sufficient to guarantee withstanding all possible loads, will be described below.

The rafters can end on the Mauerlat, but more often they go beyond the perimeter of the walls of the house, forming a cornice overhang. However, for this, lighter parts can also be used - the so-called "filly", with which the rafter legs are extended to the required overhang width.

For the formation of the eaves overhang, the rafters are extended with "filly"

3 - ridge run. It can be a bar, a board, or even a composite structure. The run runs along the entire line of the ridge and serves to reliably connect the upper points of the paired rafter legs, link all the rafter pairs in order to impart overall rigidity to the entire roof structure. In various roof options, this girder can be rigidly supported on the racks, or tied only to the junction of the rafter legs.

4 - tightening (contractions, crossbars). Horizontal details of the reinforcement of the system, additionally connecting the paired rafter legs to each other. Several puffs at different heights can be used.

5 - floor beams, which will serve as the basis for the installation of the floor in the attic and the ceiling from the side of the room.

6 - and this beam at the same time serves as a bed. This is a beam that runs along the entire length of the roof, which is a support for the installation of additional reinforcement parts for the rafter system. The bed can be installed as shown in the figure (by the type of floor beams), or rigidly laid on the main partition inside the building.

7 - racks (headstock) - additional vertical supports of the rafter legs, preventing their deflection under the influence of external loads. The racks at the top can abut against the rafters themselves, or into an additional girder that longitudinally connects the rafter legs at a certain height.

8 - struts. Often, with a large length of rafter legs, their bearing capacity is not enough, and reinforcement with only racks does not provide the necessary strength. In these cases, diagonal reinforcing elements are used, resting on the bottom from the bottom, creating an additional support point for the rafters. The number of struts and the location of their installation can vary in roofs of varying degrees of complexity.

Some differences between the hanging and layered gable roof system

Gable roofs can be divided into two types of structures - with layered and hanging rafters. In addition, combined systems are widely used, in which both principles of construction are combined. What is the fundamental difference?

Rafter roof system

This structure of the truss system is characterized by the presence of support on the internal capital partition in the building. On the upper end of this partition, a bed is mounted, on which the drains support the ridge run. Thus, the rafter legs are "leaned" on the vertical support, which makes the entire system as strong as possible.

This scheme is the most popular because of its reliability and relative simplicity in implementation. If it is possible to create an additional pivot point in the center, then why not take advantage of this? True, if it is planned to place a dwelling in the attic, then vertical racks can sometimes become an obstacle. However, their presence is also sometimes "played up", using, for example, for the installation of an internal lightweight partition.

Depending on the number and placement of internal partitions, the design of the layered rafter system may vary. Some examples are shown in the illustration below:

Fragment "a" shows the simplest version, which, by the way, on small rafter lengths (up to 5 meters) may not even have the braces shown - a row of central posts under the ridge run is enough

With an increase in the width of the building, the system naturally becomes more complicated, and additional reinforcing elements appear - puffs and struts (fragment "b").

Fragment "c" clearly demonstrates that the internal capital wall does not have to be located exactly in the center, under the ridge. It is quite possible and such an option, as shown in the illustration, but with the condition that the displacement of the bed relative to the ridge does not exceed one meter.

Finally, fragment "d" shows how a system of rafters can be supported in a building of a large size, but with two main partitions inside. The distance between such parallel planks can be up to a third of the building's width.

Hanging rafter system

Graphically, this roof scheme can be depicted something like this:

It is immediately striking that the rafters rest only on the lower part, and then are connected to each other on the ridge. There is no additional support in the center, that is, the rafter legs seem to "hang", which predetermines the name of such a system. This feature imposes certain restrictions on the use of hanging rafters - usually such a scheme is practiced when the distance between the bearing walls, on which the Mauerlat is fixed, is no more than 7 meters. Installed tightenings only partially relieve the load on the outer walls.

The illustration below shows several options for a hanging system. However, some of them already, rather, can be classified as combined.

Fragment "d" - hanging rafters are interconnected with a coupler at the level of the Mauerlat or fixed on a powerful floor beam, forming a triangle with it. There are no other reinforcing parts. A similar scheme is permissible with a distance between the walls up to 6 meters.

Option "w" - for a house of the same size (up to 6 meters). The tightening (crossbar) in this case is shifted upward, and is often used to hem the ceiling of the attic.

Options "e" and "z" are designed for a span between walls up to 9 meters. Multiple ties can be applied (or the top tie in combination with the bottom joist). Another approach is to install racks under the ridge run, similar to the layered system. Only as the lowest point of support is not a lie on the main partition, but the racks are supported by a tightening or a floor beam. Calling this option purely "hanging" is already difficult, since here is clearly a combination of parts from both designs.

To an even greater extent, such a combination of the two schemes is expressed in the “i” version, which is designed for large spans, from 9 to 14 meters. Here, in addition to the headstock rack, diagonal struts are also involved. Often, such trusses are generally assembled on the ground, and only then they are raised and installed in place, connected to each other, thereby forming the entire roof frame.

So, in preparation for the construction of a gable roof, it is necessary to study the principles of a particular system, evaluate their advantages and disadvantages, choose the optimal one for your conditions and draw up a graphical working diagram. It will be needed both when purchasing the necessary material, and for the production of the installation work itself. However, drawing up a drawing should still be preceded by some calculations.

Calculation of the basic parameters of the gable roof truss system

Let's take another look at the schematic diagram of the gable roof device in order to highlight the parameters that will need to be calculated.

So, in the calculation process, we need to decide on the following values.

The initial data is the length of the side of the house along the gable part (highlighted in blue - F), and the length of the house along the ridge (purple - D). It is assumed that the owners have already decided in advance on the type of roofing - since there will be certain restrictions on the steepness of the roof slopes. (angle a).

The height of the ridge above the Mauerlat plane (H - green), or, conversely, determine the angle of the slope, starting from the planned height of the ridge.
The length of the rafter leg (blue - L), and, if necessary, lengthening the rafter to form the eaves overhang of the required width (l).
Calculate the total loads that fall on the rafter system in order to determine the optimal cross-section of lumber for the manufacture of rafters, the pitch of their installation (red - S) and the permissible length of spans between the support points. All these parameters are closely interconnected.
When these calculated values are on hand, it is already easy to draw up a graphical diagram, determine the need and optimal location of the amplification elements, and calculate the amount of material for their manufacture.

Chainsaw prices

chainsaw

We calculate the steepness of the slope and the height of the ridge

The angle of steepness of the slopes can be determined by the owners according to various evaluation criteria:

For purely aesthetic reasons - when the appearance of the building becomes "the cornerstone". Many people like roofs with a high ridge, but at the same time we must not forget that the wind load on such a roof sharply increases. And the materials for the manufacture of a high roof will go immeasurably more. At the same time, on steep slopes, the snow load is reduced to almost zero - it is possible that for “snowy” regions this parameter of assessment may become decisive.
For reasons of useful use of the attic space. With a gable roof scheme, in order to achieve the maximum attic area, it is necessary to erect ramps with a very high steepness, that is, with the same consequences as mentioned above.

Finally, there may be a completely opposite approach - for reasons of economy, to make a roof structure with a minimum height in the ridge. But in this case, you will have to focus on the minimum permissible slope angles for a particular type of roofing. Reducing the slope below the manufacturer's recommended indicators is to "plant a bomb" in your roof, both for reasons of its strength and durability, and from the standpoint of the waterproofing qualities of the coating.

It is not difficult to calculate the height of the ridge above the floor plane (Mauerlat). The overwhelming majority of nodes of any roofing system is based on a triangle, which, in turn, obeys strict geometric (more precisely, trigonometric) laws.

So, in our case, the width of the roof along the pediment line is known. If the roof is symmetrical, then the ridge will be placed exactly in the middle, and for calculations, you can simply divide the width F by two (the base of the triangle f =F / 2). With asymmetric slopes, you will have to project the top of the ridge onto line F, and measure the distances f1 and f2 from it to the edge of the triangle (to the Mauerlat) on each side. Naturally, in this case, the slope of the slopes will be different.

H =f × tga

In order not to force the reader to look for the values of the tangents and carry out calculations manually, a calculator is placed below, in which the necessary tabular values have already been entered.

When designing any residential building, architects pay special attention to the roof, since it performs not one, but several functions at once, depending on its design features. It must be said that not all future homeowners are satisfied with the usual gable roof, although it can be called the most reliable, since it has only two pitched planes and one joint between them. Many are attracted by more complex structures, which add special appeal and originality to the structure. Other, more practical homeowners prefer skylights that can serve as both a roof and a second floor at the same time.

The basis of any roof is an individual rafter system, which has its own design features. It will be much easier to make the choice of the required roof frame if you figure out in advance which types and diagrams of rafter systems used in construction practice. After receiving such information, it will become more clear how complex such structures are in installation. This is especially important to know if the roof frame is supposed to be erected independently.

The main functional tasks of roof systems

When arranging pitched roof structures, the rafter system is a frame for covering and for holding the materials of the "roofing pie". With the correct installation of the frame structure, the necessary conditions will be created for the correct and non-insulated types of roofs that protect the walls and the interior of the house from various atmospheric influences.

The roof structure is also always the final architectural element of the exterior design of the building, supporting its stylistic direction with its appearance. Nevertheless, the design features of the rafter systems must first of all meet the strength and reliability requirements that the roof must meet, and only then - the aesthetic criteria.

The frame of the rafter system forms the configuration and angle of inclination of the roof. These parameters largely depend on natural factors specific to a particular region, as well as on the desire and capabilities of the homeowner:

The amount of precipitation in different periods of the year.
The direction and average speed of the wind in the area where the building will be erected.
Plans for the use of space under the roof - arranging residential or non-residential premises in it, or using it only as an air gap for thermal insulation of the premises below.
A type of planned roofing material.
The financial capabilities of the homeowner.

Atmospheric precipitation and the strength of wind flows give a very sensitive load on the roof structure. For example, in regions with heavy snowfalls, you should not choose a rafter system with a small angle of inclination of the slopes, since the snow masses will linger on their surface, which can lead to deformation of the frame or roofing or to leaks.

If the area where the construction will be carried out is famous for its winds, then it is better to choose a structure with a slight slope of the slope so that the sudden gusts that occur do not tear off individual elements of the roof and roof.

Basic elements of the roof structure

Details and assemblies of rafter systems

Depending on the type of rafter system chosen, the structural elements used can vary significantly, however, there are details that are present in both simple and complex roof systems.

The main elements of the rafter system of a pitched roof include:

Rafter legs that form the roof slopes.
- a wooden beam, fixed on the walls of the house and serving to fix the lower part of the rafter legs on it.

The ridge is the joint of the frames of the two slopes. It is usually the highest horizontal line of the roof and serves as the support on which the rafters are anchored. The ridge can be formed by rafters, fastened together at a certain angle, or fixed on the ridge board (run).
The lathing is slats or beams mounted on rafters with a certain pitch and serving as the basis for the flooring of the selected roofing material.
Retaining elements, which include benches, girders, racks, struts, ties and other parts, serve to increase the rigidity of the rafter legs, support the ridge, and tie individual parts into a common structure.

In addition to the aforementioned structural details, it can include other elements, the functions of which are aimed at strengthening the system and optimal distribution of the roof loads on the walls of the building.

The rafter system is divided into several categories, depending on the different features of its design.

Attic space

Before moving on to considering different types of roofs, it is worthwhile to figure out what an attic space can be, since many owners successfully use it as utility and full-fledged living quarters.

The design of pitched roofs can be divided into attic and attic. The first option is called this way because the space under the roof has a low height and is used only as an air gap that insulates the building from above. Such systems usually include or has several slopes, but located at a very slight angle.

The attic structure, which has a sufficiently large ridge height, can be used in different ways, be insulated and not insulated. These options include the attic or gable version. If a roof with a high ridge is chosen, then it is imperative to take into account the wind loads in the region where the house is built.

Slope of ramps

To determine the optimal slope of the roof slopes of a future residential building, first of all, you need to take a closer look at the already built low-rise neighboring houses. If they have been standing for more than one year and can withstand wind loads, then their design can be safely taken as a basis. In the same case, when the owners set the goal to create an exclusive original project, unlike the buildings standing nearby, it is necessary to familiarize yourself with the design and operational features of various rafter systems and make the appropriate calculations.

It should be borne in mind that the change in the tangential and normal values of the wind force depends on how large the slope of the roof slopes is - the steeper the angle of inclination, the more important are the normal forces and the less tangential. If the roof is sloping, then the shear wind load affects the structure more, since the lifting force increases from the leeward side and decreases from the windward side.

The winter snow load must also be taken into account when designing the roof. Usually this factor is considered in conjunction with the wind load, since the snow load on the windward side will be much lower than on the leeward slope. In addition, there are places on the slopes where snow will necessarily collect, giving a large load on this area, so it should be strengthened with additional rafters.

The slope of the roof slopes can vary from 10 to 60 degrees and should be selected not only taking into account the consolidated external load, but also depending on the roofing to be used. This factor is taken into account because roofing materials differ in their weight, their fixing requires a different number of elements of the rafter system, which means that the load on the walls of the house will also differ, and how large it will be, also depends on the angle of the roof slope. Of no small importance are the features of each coating in terms of resistance to moisture penetration - in any case, many roofing materials need one or another slope to ensure the free flow of storm water or melting snow. In addition, when choosing the slope of the roof, you need to think in advance about how the process of cleaning and repair work on the roof will be carried out.

When planning this or that angle of the roof slopes, you need to know that the fewer joints between the sheets of the coating, and the more airtight they are, the less you can make the slope of the slope, of course, if it is not supposed to arrange a residential or utility room in the attic space.

If a material consisting of small elements is used to cover the roof, for example, ceramic tiles, then the slope of the slopes must be made steep enough so that water never lingers on the surface.

Considering the weight of the roofing material, you need to know - the heavier the coating, the greater the angle of the slopes, since in this case the load will be correctly distributed to the rafter system and load-bearing walls.

The following materials can be used to cover the roof: either a profile sheet, galvanized steel, corrugated asbestos concrete and bitumen-fibrous sheets, cement and ceramic tiles, roofing material, soft roofing and other roofing materials. The illustration below shows the acceptable slope angles for various types of roofing.

Basic constructions of truss systems

First of all, it is worth considering the basic types of rafter systems in relation to the location of the walls of the house, which are used in all roof structures. Basic options are divided into layered, hanging, and also combined, that is, including elements of both the first and second types of systems in its design.

rafters

Nasal system

In buildings where internal load-bearing walls are provided, a layered rafter system is often installed. It is much easier to mount it than a hanging one, since the internal load-bearing walls provide reliable support for its elements, and in addition, this structure will require fewer materials.

For rafters in this system, the defining reference point is the ridge board, on which they are fixed. The spreader-free type of the layered system can be equipped in three options:

In the first version, the upper side of the rafters is fixed on a ridge support, called sliding, and their lower side is fixed by cutting to the Mauerlat. Additionally, the rafters in the lower part are fixed to the wall using wire or staples.

In the second case, the rafters in the upper part are cut at a certain angle and connected to each other using special metal plates.

The lower edge of the rafter legs is attached to the Mauerlat with movable fasteners.

In the third version, the rafters are rigidly fastened in the upper part with bars or treated boards, located horizontally, parallel to each other on both sides of the rafters connected at an angle, and the ridge girder is pinched between them.

In the lower part, sliding fasteners are used to secure the rafters, as in the previous case.

It is necessary to explain why sliding fasteners are often used to fix the rafters on the Mauerlat. The fact is that they are able to relieve the load-bearing walls from excessive stress, since the rafters are not rigidly fixed, and when the structure shrinks, they can move without deforming the overall structure of the roofing system.

This type of fastening is used only in layered systems, which also distinguishes them from the hanging version.

However, in some cases, a spacer system is used for layered rafters, in which the lower end of the rafters is rigidly fixed to the Mauerlat, and in order to remove the load from the walls, puffs and struts are built into the structure. This option is called complex, since it includes elements of a layered and hanging system.

The rafter system is the foundation of any roof. The complexity or availability of the rafter structure depends on the type of roof chosen. Today we will talk about the simplest option - a rafter system for a gable roof. Experienced specialists tell about the structure of the roof frame, the features and functions of its elements, and how the gable roof rafter system is carried out with their own hands.

Gable roof: types and advantages

Recall that a gable roof is a type of roof consisting of two planes (slopes) connected at an angle of a certain degree. It can be simple (symmetrical or asymmetric) and complex - broken.

The rationality of choosing a roof from two slopes is determined by its following advantages:

Efficiency and ease of construction, in comparison with other roofing structures.
Ease and availability of service at any time of the year.
Reliability and durability against wind, snowfall, hail and other natural influences.
The possibility of arranging the attic.
Better quality hydro and thermal insulation.

The required theoretical minimum for the construction of a rafter system

The pitched roof structure is made of metal or wooden beams. Metal is a more “problematic” material. It makes the entire roofing system heavier, cools and heats up quickly, is more difficult to install and requires the use of professional welding equipment. Based on this, in the construction of private houses (especially with your own hands), wood is mainly used.

There are two main options for performing a rafter system for a gable roof - a hanging type device (each rafter leg has two support points) and a layered method (the rafters are connected at the bottom by tightening, forming a triangular truss, a load-bearing beam is installed in the middle). An elevated structure is necessary if there is a distance of more than 10 meters between the load-bearing walls. Look at the image:

What is their rafter system? Let's imagine a 3D projection. The skeleton of the roof consists of a mauerlat (rafter base), rafter legs, a ridge, racks, girders, a bed, puffs, struts and lathing. Mauerlat, lying and tightening are the lower parts of the system on which the entire future roof is being erected. Take a look at the illustration below first and then look at each element separately:

Mauerlat is the basis of all foundations

Mauerlat is a solid wood (mainly coniferous) timber with a section of 10-15 cm. These are the optimal dimensions for the required strength and durability of the entire roofing structure. The beam is laid on the load-bearing walls of the house to redistribute the spacer load on them.
There are two ways to install the rafter base bars - with the transfer of the load to the walls and without the transfer of gravity. The choice of the mounting option for the Mauerlat should depend on the severity of the roofing system, the coating, the thickness of the load-bearing walls and the perimeter of the roof.

With the latter option, the Mauerlat is put into a pocket, closer to the inner edge of the wall, and is attached to wooden corks with staples (each cork corresponds to the size of the brick and is part of the top row of brickwork).

The load-bearing bars are mounted on the load-bearing walls from above using anchors. Craftsmen advise putting a rigid frame on a concrete base in the form of a belt in the wall. High-quality waterproofing must be installed under the Mauerlat.

Details can be found in the video:

Lezhen - basic load balancer

Lezhen performs functions similar to the Mauerlat, and has the same dimensions. Beams are laid on internal load-bearing walls in order to evenly distribute the loads from the uprights and struts.

See the illustration for a master class on the installation of beds:

Rafter legs - ribs of the roof skeleton

Rafters can be called the main component of the roof frame. This element cannot be omitted or replaced with another part. The legs of the rafters are wooden beams, the cross-sectional size of which can vary from 5 to 15 cm. The rafters rest on the Mauerlat and are connected with a ridge.

The process of installing rafters can be seen in this video:

The horse is a small nuance with a big meaning

The final element of the joint of the two slopes is called the ridge of the roof. This is a rib located vertically at the highest point of the roof. At the junction of the rafters, a ridge girder is mounted. After that, the roof ridge is installed on it. This element holds the rafters together, performs a ventilation function and makes the roof aesthetically pleasing.

Racks - receivers of main loads

Racks are powerful beams that take part of the load of the rafter structure. They are installed vertically, usually in the center of the truss. If the project provides for an attic, then the racks are placed on both sides, closer to the roof slopes. When the attic is divided into two rooms, the racks are placed both in the center and on the sides.

Purlins - support for rafters

The ridge and side girders serve as a reinforcement of the rigidity of the truss trusses. The greater the load on the system (snowy winters, heavy roofing, large roof area, etc.), the more purlins must be installed on the roof slopes.

Tightening - truss connector

This part of the structure performs the function of fixing the rafters at the base. Thus, a truss triangle is formed - a truss. Tightens may not be installed on stack-type systems.

Braces - the strength of the structure

The struts serve as a support for the uprights and strengthen all structural elements. Experts recommend installing struts at an angle of 450. This increases the strength of the system and protects it from deformation under the influence of snow and wind.

The lathing is the basis for the roofing cake

Lathing - horizontal wooden slats with a cross section of 40-50 mm, located on the slopes perpendicular to the rafters. The main purpose of the lathing is to fix the roofing material. The frequency and thickness of the battens depend on its type. In addition, the lathing helps to move materials during the roofing and serves as an additional element of structural strength.

Overhang elements - finishing points

The edge of the roofing system is called the overhang. This is the protrusion of the rafter system above the wall by about 40 cm. The overhang box consists of the following elements: filly (connection rails with rafters), frontal and cornice boards. The purpose of the overhang is to protect the walls from getting wet during rains and melting snow.

Step-by-step installation guide for gable roof truss system

To begin with, we suggest that you familiarize yourself with the illustration that we have prepared for you:

And now we will consider the three main stages of the process of constructing the truss system of a simple gable roof:

Stage 1: Calculations and project preparation

Work should begin with the preparation of a roof project. It will contain all sizes, shapes and types of fasteners for structural elements. To create a quality project, you need to make the following calculations:

Calculation of permanent and variable loads on the rafter system. Permanent loads include the weight of the roof and finishing materials (the attic is also taken into account additionally). Variable loads are the force of wind, rain, snow, etc. The maximum load can be considered the main load up to 50 kg per square meter of the roof, and variable - up to 300 kg (taking into account possible snow blockages).
Accounting for seismic activity, storm winds and the peculiarities of the location of the house. For example, if the house is surrounded by other buildings, the load on the roof is significantly reduced.
The choice of the angle of inclination of the gable roof. When calculating the angle of inclination, the following factors are taken into account: the higher the angle, the more materials will go to the roof (and money, respectively); the slope depends on the roofing material - the softer the roof, the smaller the slope angle (for example, for soft tiles, an angle of 5-200 is chosen, and if you use slate or ondulin, you must choose a slope of 20-450).
Calculation of the step and length of the rafters. The length of the step between the trusses varies from 60 to 100 cm. The heavier the roof covering, the more often the rafters need to be distributed. To calculate the length of the rafter, we use the Pythagorean theorem, taking the rafter leg for the hypotenuse of the triangle. The first side will be considered half the width of the house, and the second - the selected roof height. Then add another 60-70 cm of stock to the hypotenuse we found.

When all the calculations are done, you need to make a drawing of parts, connections and the entire project as a whole.

Stage 2: Acquisition and preparation of the necessary materials and tools

For work, you need to purchase lumber, according to calculations, bolts, corners, anchors and other connecting parts, and prepare the appropriate tools (drills, levels, meters, jigsaw, etc.). Wood for load-bearing beams and rafters must be solid and of high quality - knots and wormholes are unacceptable.

Antiseptic, anti-corrosive and fire-fighting wood processing is a must at this stage. You can start working with the material one day after processing.

Stage 3: Installation of the roof truss structure

It is better to mount the roof frame in dry, not windy weather, so as not to face additional difficulties during work. At this stage, we will dwell in more detail and consider the step-by-step instructions for installing the rafter system.

Installing the rafter system: a step-by-step guide

Step 1. Laying the Mauerlat and the bed. The bed may not exist if there are no more load-bearing walls inside the house. Before laying the Mauerlat on the walls, it is necessary to lay a waterproofing material, for example, roofing material. We measure the tape of the required width, cut it off and lay the waterproofing on the edge of the wall (where the frame will be installed).

We mark the beams of the desired section and length, cut them off and begin to form the base frame. Mauerlat should be located on the outer edge of the wall (if a hanging structure is planned) or in a special niche on the wall in front of the threshold (if the roofing system is layered). The beds for the racks are laid on the internal load-bearing partitions. The Mauerlat is attached to the wall and wooden corks with staples, studs and anchors.

And we suggest that you familiarize yourself with the illustration that we have prepared for you:

When laying the frame along the entire length of the wall, we may be faced with the need for joining the base beam. They should be performed by cutting the bars at an angle of strictly 90 degrees. We carry out fastening with high-quality bolts.

How to avoid damaging bricks or blocks when lifting roofboards?

Select the edge of the wall through which it is most convenient to feed the beams for the roof frame. Protect this edge with a wooden square. Two trims of a roughing board about a meter long are suitable, which need to be knocked together at a right angle. Slide a square to the outside edge of the work wall. Now you can lift the boards without fear of damaging walls or window sills.

Step 2. Installation of rafters. The first step is to install the extreme rafters. In order to keep the rafters straight, we install the racks in the center. We attach the racks to the Mauerlat using an iron angle and self-tapping screws. This temporary piece is removed after all the rafters have been installed. We fasten the extreme rafters with crossbars and install the ridge girder. Fastening type - metal corner, screws and pins.

The illustration shows the process of installing the rafter legs and attaching the rafters to the purlin:

And here's how to attach the rafters to the Mauerlat:

Between the extreme trusses, it is imperative to pull a construction thread, along which we will level all the rafters of the ramp.

Now we mount all the rafter elements according to a pre-marked scheme. We join the rafters over the ridge run.

For more information on the process of installing rafters, see this video:

A system of special racks will help to strengthen the rafter legs. Wooden blocks of boards of the same thickness as the rafters are attached to the Mauerlat. The bars should be fixed with a step equal to the selected distance between the rafter legs along the markings. The length of each board is approximately 40 cm. These racks will transfer the load to the Mauerlat and load-bearing floors. The bars must be fixed to the base with steel corners. Now the rafter legs need to be installed so that one side of each is adjacent to the rack. Then, on the other side of each rafter, we attach the same rack and grab all three parts with 12 mm studs.

After installing all the legs, the racks are trimmed flush with the rafter bevel from the street side. An empty corner is formed from the inside between the posts, which must be closed with a wooden triangle (you can use trimming from bevels).

All rafter legs should be additionally reinforced with crossbars, uprights, struts and reinforced with metal plates. The complete process of strengthening the rafters can be seen in the video:

Step 3. Waterproofing and lathing. On the finished rafter ribs, you need to lay a high-quality waterproofing vapor-permeable material under the crate. The entry of the insulating sheet (sheet to sheet) is made 15 cm. A counter lathing of wooden slats is stuffed onto the waterproofing along the rafter edges. A crate of the same slats is installed on top perpendicular to the rafter legs.

When installing the frame, it is necessary to take into account the presence of a chimney and the mandatory ventilation of the ridge. The distance between the battens is on average 300 mm. This scheme is suitable for all types of solid roofing. When choosing a soft roofing material, the lathing is made solid from sheets of moisture-resistant plywood.

The rafter system is ready. Now it is the turn of the installation of roofing material, internal insulation of the roof and the arrangement of the attic (if such is provided for by the project).

So, it's time to answer the main question of our topic: is it worth doing it all with your own hands? Do not trust someone who tells you that it is easy and simple. But if you have golden hands and a great desire to make a high-quality roof "for yourself", then go ahead! We wish you good luck!

Roofing structures - one of the most difficult in the design, installation of units of a residential building. The roof is the first to take the "blow", protecting the house from precipitation, wind and cold, therefore the comfort of all households depends on its tightness, durability, quality. The basis of a reliable roof is the rafter system, which gives the structure its shape, sets the optimal slope, and also serves to fix the waterproofing material. The composition and relative position of the frame elements depend on the configuration of the roof. In this article we will tell you what types of rafter systems are, as well as how they differ from each other.

The rafter system is a set of supporting elements that support the geometry of the roof, the frame of the roofing structure, which gives it rigidity, the desired slope. The composition, the thickness of the section, the location of the parts of the "backbone" of the roof are determined using calculations that take into account permanent and temporary loads. The rafter frame performs the following functions that determine the functionality of the roof:

Specifies geometry, slope. The rafter legs of the frame give the roof the necessary angle of inclination and shape, facilitating the relief of snow or precipitation from the surface. It depends on the frame how many tongs or slopes the roof will have, which means it is this structural element that determines its appearance.
Serves as the basis for fastening waterproofing material. The roof frame lathing is used to fix the roof topcoat.
Distributes the weight of the roof evenly. The interconnected elements of the rafter system evenly distribute, and then redirect the load from the topcoat and the weight of the snow mass between the load-bearing walls of the structure, preventing skewing or deformation of the structure.
Ensures the functioning of the roof. The structure of the frame, which takes into account the features of the roof and roof covering, provides support, aeration and protection against condensation.

Please note that a well-designed rafter system is the key to the durability, reliability and mechanical strength of the roof, therefore, professional architects are entrusted with its design and installation. Experienced craftsmen believe that a high-quality frame is much more important than a finishing roofing, so you should not save on it.

Criterias of choice

The device of the rafter system is distinguished by a large number of auxiliary elements and increased complexity. It is drawn up according to the calculation of permanent and temporary loads acting on the structure, a project that takes into account the selected roofing material, as well as environmental factors. When choosing the type of rafter frame, the following criteria are taken into account:

Climatic conditions in the region where construction is underway. In order for the roof to withstand the weight of snow and water during heavy rainfall, the average annual rainfall is determined in winter and summer.
Wind load. To select the optimal roof design, the prevailing wind rose in the construction area is determined, and the average speed of air gusts is also taken into account.
The nature of the use of space under the roof. At this stage, it is determined whether a residential attic in an under-roof space or an unheated attic will be equipped.
A kind of topcoat. For each material, the optimal slope angle of the slopes is calculated, taking into account its shape and method of attachment.
Developer's budget. The rafter system is one of the most costly part of the roof structure in terms of material and work, therefore the type is determined by the financial capabilities of the developer.

Experienced craftsmen believe that it is useless to fight nature, you will still be a loser, therefore, when choosing the type of rafter frame, they put climatic conditions in the area where the construction is underway. If the region is windy, then the angle of inclination of the slopes is made gentle, and if it is snowy, it is steeper.

Materials (edit)

The rafter system is an indispensable element of pitched roofs of any shape and configuration, consisting of vertical supports, horizontal ties and rafter legs that provide support and reliable fastening to the roofing material. The material used for the manufacture of the frame must be lightweight, high strength, load-bearing capacity, as well as resistance to moisture. The most suitable options are:

Wood. Wood is a natural, environmentally friendly material that is lightweight and durable. For the manufacture of the frame, square bars of 100x100 mm or 150x150 mm are used, boards with a section of 50x150 mm of hard rocks. A significant disadvantage of wooden frame elements is that they sag under their own weight with a large length, and also have a weak resistance to moisture.
Metal. Metal truss systems are more expensive than wooden ones; they are used mainly with a large area of slopes and a large weight of the roofing material. The high bearing capacity of a metal profile or corner allows you to increase the pitch between the frame elements without losing the strength of the structure. To reduce the likelihood of rust spreading, corrosion-resistant metals are used.

Note! Wood is considered the most suitable material for the manufacture of roof truss for residential buildings, as it has 3 important qualities: light weight, strength, and air permeability. To increase the resistance of wood to moisture, it is necessary to treat the elements of the rafter system with a deeply penetrating antiseptic.

Device

The device of the roof rafter system consists of many interconnected elements, which, supporting each other, give the structure the rigidity, the necessary strength, and also distribute the weight of the roofing material evenly between the bearing supports. The composition of the frame, the size of the section of individual elements and their placement depend on the type of topcoat, the slope of the slope and the method of using the under-roof space. Usually the frame consists of:

Mauerlat. Mauerlat is called a rafter, which is attached over the top crown or a row of load-bearing walls of the house. It is made from durable, hard coniferous wood. The Mauerlat is fastened using long metal studs or anchor bolts.
Lezhenya. A bed is called a Mauerlat beam, located not on the external load-bearing walls, but on the internal partitions. The central pillars are installed on the bed, supporting the ridge of the roof.
Racks. Racks are vertical support elements that support the ridge girder or the central part of the frame rafter legs.
Rafters. The rafter legs rest on the Mauerlat and the ridge girder, positioned at an angle to the base of the roof.
Crossbars and tightening. These terms are called horizontal elements of the frame, pulling together the rafter legs in pairs. The crossbar is located at the top of the rafters, just under the ridge, it is thicker and stronger than the tightening, which is located much lower.
Podkosov. The brace is installed at an angle to the rafters to prevent them from sagging under their own weight. With one end they rest on the leg, and with the other, in a stand or puff.

Important! The simplest rafter system consists only of a Mauerlat, rafters and a ridge girder. With an increase in the complexity of the roof, the number of additional elements that strengthen the structure, as well as compensate for the load on deflection and expansion, increases.

Views

The configuration of the roof frame depends on the architectural features of the structure to be covered. The roof must take into account the number of load-bearing supports inside or outside the house in order to evenly distribute the load placed on them. There are the following types of rafters:

Please note that the final appearance of the rafter frame made of wooden or metal elements depends on the number of slopes and the type of roof. The simplest options are single-pitched and gable roofs, and complex ones are hip, half-hip, hip roofs.