There can be no doubt that the reliability of the roof is one of its important characteristics. This design is based on truss bearing trusses. Their installation can be called responsible and time-consuming work, which provides for accurate calculations. The rafter system must undergo the weight of covering materials, insulation, crates and precipitation in the form of ice and snow. Given all these factors, 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 includes the seismicity of the development area.
Design
Wooden trusses are assembled from hanging and inclined rafters, Mauerlat, ridge runs, struts, diagonal ties and braces. The connected parts form a truss truss, which has the form of a triangle or several triangles interconnected. The bearing part of the roof structure is the rafter system, which is also called the rafter legs. The angle at which they are installed corresponds to the angle of inclination of the roof.
Do-it-yourself wooden trusses are made by technology, which involves 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 girder are connected, the last of which is called the skate beam. In this part is the ridge of the roof. The distance between the rafters should be determined by the characteristics of the roof material, the cross section of the rafters, as well as other factors. This parameter can vary from 0.8 to 2 m.
What else you need to know about the design of truss trusses
Wooden trusses, as mentioned above, consist of rafter legs. They should be located parallel to the slopes, their task is to eliminate the deflection of the roof structure. If we are talking about the run, then it is performed in the form of a transverse beam, which is located longitudinally from above. To support the runs of the truss structure, stands and lodges act. The components of the truss truss are struts, it is thanks to them that the stability of the rafters is ensured.
Settlement
Calculation of a wooden truss, of course, is best entrusted to professionals, in the process of this work, 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 cake. While temporary loads are precipitation and the weight of people who can climb the roof for repair work. This should also include the wind factor.
Special loads are those that the building is exposed to in areas with increased seismic hazard. The most important is the calculation of snow load, which is performed by the formula: S = Sg x μ, in it Sg is the mass of snow load per square meter. This parameter is conditional, and the value is determined by the table depending on the region. As for the value of μ, it is a coefficient depending on the angle of inclination of the roof. In order to determine the wind load, you should know in which zone the house is located, it can be an open space or urban development.
The design of the wooden truss is calculated, also based on the standard value of the wind load in a particular region. It is necessary to take into account the height of the building. 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 similar elements should be 120 cm. With an increase in the cross-section of the beam to 8x18 cm and the length of the rafters to 4 m, the distance will be 140 cm. The maximum value is the cross-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 other elements of the roofing system, they should have the following sections: Mauerlat - 15x15 or 10x15, diagonal rafter legs - 10x20, puffs - 5x15, struts - 10x10, as well as runs with the last of the mentioned sections.
It is important to know the cross-section of crossbars and binder boards, in the first case this value will be 10x15, while in the second - 2.5x10 cm. If you install wooden truss trusses, then you can easily calculate the required number of elements, knowing the rafter cross-section and 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 based on which further work will be performed. Rafters have the same design, so the template saves time and effort. Two boards on one edge should be connected with a nail, as a result, a design will be obtained that looks like scissors. When wooden trusses are done with your own hands, the free edges of the resulting scissors need to be installed on the supports at the points of the rafters. This will determine which slope the roofing slope will have.
An additional pair of nails will allow you to fix the corner, which is located between the boards. At this stage, we can assume that the template is ready. In addition, it can be fixed using the crossbar. In order that the angle does not change under the influence of loads, the crossbar can be fixed with screws.
Methodology
If you decide to make wooden trusses, then you should be careful when creating the template, even if it will have minimal deviations, the whole structure is skewed. At the next stage, you need to run a new template for preparing rifling on the elements of the system. In this case, 0.5 cm plywood should be stocked, for fixing you should use a board whose thickness is 2.5 cm.
Conclusion
Rifling should be selected, given the cross section of the rafters. When wooden trusses are made, with the help of ready-made templates, you can make rifles and start assembling the farm.