These are usually triangular frames that are used to build a roof. Rraft farms made of wood in special factories are made. For connections on both sides, galvanized carbon plates made of stainless steel, thickness 1-3 mm are used on both sides. Farmers are produced using special equipment – press and sprayers of anti -corrosion agents. In general, they allow fars for roofs of various heights and size, as well as individual parts, which can be collected already on the spot. Which is quite convenient during the construction of large buildings or combined roofs.
Other methods of wooden farms are also used using nails, bolts and brackets. Most often use nails and brackets, but over time, in the process of drying the tree, the structure may lose its reliability. And this is unacceptable for the bearing part of the roof. It is more reliable to use bolts, but the holes reduce the strength of the bars.
Wooden rafter farms are mounted at a distance of 0.6-2.0 m, depending on the size of the rafters and the material from which the roof will be built, taking into account the pressure of wind and precipitation. Farms can only be installed on the outer walls, on two extreme points, as well as on the last points and on the supporting internal wall.
The rafters are under the constant load of their own weight, crate, roof weight and periodic natural factors, such as wind and snow. In the calculations when constructing rafter farms, they can make amendments to the wind if the degree of the slope of the roof exceeds 30 ° and depending on the climatic conditions of the terrain, amendments to the snow and other precipitation are made.
Farms are installed on Mauerlat – this is a special beam that is located around the perimeter of the building, and sometimes along the internal walls, too. In wooden buildings, the Mauerlat has the upper part of the beam. A beam is installed on the brick walls, in one level with the inside of the wall, and covered with brick from the outside. Not forgetting about the waterproofing layer between the beam and brickwork.
At the very top of the farm, they are interconnected using a ridge run, which is then used for the skate of the roof. To strengthen the structure in the slopes of the roof, diagonal bonds are made, they provide additional strength of the entire structure.
When the assembly of rafter farms is over, they make a crate. After assembling rafters (rafter farms), a crate is arranged. These are the boards that are nailed along the entire length of the roof, perpendicular, to the bars of the farms forming the lattice design, which in the process serves as the basis for installing roofing material and gives additional stability. The crate can be made of boards or bars, laying them with the required frequency depending on the weight of the roof coating. If the roof is made of metallo -tank, flat slate or soft materials then make an actually continuous crate with a distance of a maximum of 1 cm between the boards. For cement or clay tiles, wavy slate and steel roof, a greater distance is made.