There is no doubt that the reliability of the roof is one of its important characteristics. At the heart of this design are truss bearing trusses. Their installation can be called responsible and time-consuming work, which involves accurate calculations. The rafter system must endure the weight of covering materials, insulation, battens and precipitation in the form of ice and snow. Given all these factors, the rafters should be given maximum strength. You can make them yourself, but for this it is important to take into account the region in which the house is built, as well as all its features, including wind and snow loads. This should include the seismicity of the building area.
Design
Wooden trusses are assembled from hanging and inclined rafters, mauerlat, ridge runs, struts, diagonal braces and braces. The connected parts form a truss truss, which looks like a triangle or several triangles connected to each other. The supporting part of the roof structure is the rafter system, which is also calledrafter legs. The angle at which they are installed corresponds to the angle of the roof.
Do-it-yourself wooden trusses are made using a technology that provides for the installation of rafters on a Mauerlat located on the wall. This is required for even weight distribution. In the upper part, the ends of the rafters and the run are connected, the last of which is called the ridge beam. In this part is the ridge of the roof. The distance between the rafters should be determined by the characteristics of the roofing material, the section of the rafters, and other factors. This parameter can vary from 0.8 to 2 m.
What else you need to know about truss design
Wooden trusses, as mentioned above, consist of rafter legs. They should be located parallel to the slopes, their task is to exclude the deflection of the roof structure. If we are talking about a run, then it is performed in the form of a transverse beam, which is located longitudinally on top. Racks and beds protrude to support the girders of the truss structure. The components of the truss truss are struts, it is thanks to them that the stability of the rafters is ensured.
Settlements
The calculation of a wooden truss, of course, is best entrusted to professionals, in the process of these works, loads that are called permanent, as well as temporary and special, should be taken into account. The first is the weight of the components of the roofing pie. Whereastemporary loads are weather precipitation and the weight of people who can climb the roof to carry out repairs. This should also include the wind factor.
Special loads are those that a building is exposed to in areas with increased seismic hazard. The most important is the calculation of the snow load, which is performed according to the formula: S \u003d Sg x Μ, in which Sg is the mass of snow load per square meter. This parameter is conditional, and the value is determined according to the table depending on the region. As for the value of Μ, it is a coefficient depending on the angle of the roof. In order to determine the wind load, you should know in which area the house is located, it can be open space or urban development.
The design of a wooden truss is calculated, also based on the standard value of the wind load in a particular region. The height of the building must also be taken into account. But in order to determine the distance between the rafters, you should know 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, then the distance between such elements should be 120 cm. If the cross section of the beam is increased to 8x18 cm and the length of the rafters is up to 4 m, the distance will be 140 cm. The maximum value is the section, which is equal to 10x20 cm, while the length of the rafters should not be more than 6 m, the distance between them will be 140 cm.
As for the remaining elements of the roofing system, they must have the following sections: Mauerlat - 15x15 or 10x15, diagonalrafter legs - 10x20, puffs - 5x15, struts - 10x10, as well as runs with the last of the sections mentioned.
It is important to know the cross section of the crossbars and filing boards, in the first case this value will be 10x15, while in the second it will be 2.5x10 cm. If you install wooden trusses, you can easily calculate the required number of elements, knowing the cross section of the rafters and the length. It is also important to know the installation step.
Production of roof trusses
At the first stage, the wizard needs to create a template on the basis of which further work will be performed. Rafters have the same type of design, so the template saves time and effort. Two boards along one edge must be connected with a nail, resulting in a design that looks like scissors. When do-it-yourself wooden trusses are made, the free edges of the resulting scissors must be installed on supports at the points where the rafters are placed. This will determine what slope the roof slope will have.
An extra pair of nails will allow you to fix the corner that is between the boards. At this stage, we can assume that the template is ready. Additionally, you can fix it with the help of a transverse crossbar. To ensure that the angle does not change under the influence of loads, the crossbar can be fixed with self-tapping screws.
Work methodology
If you decide to make wooden trusses, you should be careful when creatingtemplate, even if it has minimal deviations, the whole structure will squint. At the next stage, you need to make a new template for preparing rifling on the elements of the system. In this case, you should stock up on 0.5 cm plywood, for fixing you should use a board whose thickness is 2.5 cm.
Conclusion
The grooves should be selected taking into account the section of the rafters. When wooden trusses are made, using ready-made templates, you can make cuts and start assembling the truss.
