Wooden roof trusses with your hands: construction, calculation


2018-03-23 14:22:10




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Impossible to doubt that the reliability of the roof is one of its important characteristics. The basis of this design are the load-bearing rafter farm. Their installation can be called responsible and time-consuming job that involves carrying out exact calculations. Rafter system needs to endure the weight of covering materials, insulation, sheathing and atmospheric precipitation in the form of ice and snow. Considering all these factors, the rafters should give maximum strength. They can produce its own, however, it is important to consider the region in which a building was erected, and all its features, including wind and snow loads. This includes seismicity of area of construction.


wooden farm

Wooden farm are collected from the suspension and the sloping rafters, mauerlat, ridge runs, struts, diagonal ties and struts. Connected parts form a truss farm, which has the form of a triangle or multiple triangles connected to each other. The carrier portion of the roof structure – is a system of rafters are called rafter feet. The angle at which they are set, matches the angle of the roof.

Wooden farm with his own hands manufactured according to the technology, which involves the installation of rafters on mauerlat, located on the wall. This is required for even distribution of weight. In the upper part are connected to the ends of the rafters and run, the latest of which is called podkorytovym beam. In this part there is a ridge of the roof. The distance between the rafters must be determined by the characteristics of the material of the roof section rafters, and other factors. This parameter varies from 0.8 to 2 m.


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What else should I know about the design of roof trusses

wooden roof trusses

Wooden farm, as mentioned above, consist of the rafters. They should be placed parallel with the rays, as their goal is elimination of deflection of the roof structure. If we are talking about the run, it is executed in the form of a cross bar, which is located longitudinally on the top. To support purlins truss are struts and sleepers. The components of the secondary trusses – braces, thanks to them ensures the stability of the rafters.


calculation of wood trusses

Calculation of a wooden farm, of course, best left to professionals, in the course of these papers should take account of load, which are called permanent as well as temporary and special. The first is the weight of the components of the roofing. While the temporary load – weather precipitation and weight of people who can climb to the roof for repairs. This should include the wind factor.

Special loads are those experienced by the building in areas with high seismic hazard. The most important is the calculation of the snow load, which is performed by the formula: S=Sg x μ, it's Sg – weight of snow load per square meter. This parameter is conditional and value is determined by a table depending on the region. With regard to the values of μ, it is a factor that depends on the angle of the roof. To determine the wind load, need to know which zone the house is located, it can be open space or urban development.

The Design of wood trusses calculated still on the basis of the standard value of wind load in a certain region. You must take into account the height of the building. But in order to determine the distance between the rafters should be aware of their cross-section and length. If the cross section of the beam is 8x10 cm and the length of the rafters does not exceed 3 m, the distance between these elements should be 120 cm With the increase of the cross section of the beam to 8x18 cm and the length of the rafters up to 4 m distance will be equal to 140 cm. as the maximum value is the section, which is 10x20 cm, while the length of the rafters should not be more than 6 m, the distance between them will be equal to 140 cm.

As for the rest of the roofing system, they should have the following sections: mauerlat – 10x15 or 15x15, diagonal truss legs – 10x20, tightening – 5x15, struts – 10x10 and runs with the latter sections.

It is Important to know the cross section of the girders and blind stitch boards, in the first case the value will be 10x15, whereas in the second – 2,5x10 cm If you will install roof trusses are wood, you will easily be able to calculate the required number of elements, knowing the cross section of the rafters and length. It is important to know the step of installation.

Manufacturer of roof trusses

the design of wood trusses

In the first stage, the wizard requires to create a template, which will be further work. The rafters have the same type of design, so a template saves time and effort. Two boards, one edge should be connected with a nail, the result is a design that resembles a pair of scissors. When performed wooden farm with his own hands, the free edge of the received scissors have to be installed on the support locations of the rafters.This will allow you to determine which slope will have slope roofing.

An Extra set of nails will allow you to position the angle, which is between the boards. At this stage we can assume that the template is ready. Additionally, you can fix it with a cross bar. In order that the angle did not change under load, the rail can be fixed with screws.

Technique works

wooden farm with his own hands

If you decide to manufacture wooden farm, you should be careful when creating the template, even if it will have minimal deflection, all design mowing. The next step is to implement a new template for preparation of the grooved elements of the system. In this case you should have a 0.5-cm plywood for fixing you should use a Board thickness of which is equal to 2.5 cm.


The Rifling should be selected given the cross section of the rafters. When manufactured roof trusses are wooden, with ready-made templates, you can make a thread and to start a farm.

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