In houses with a central load-bearing wall,

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The design of a broken mansard roof is chile mobile database complex to manufacture and can only be justified for narrow spans, when the dimensions of the mansard are difficult to fit into a simple triangular roof shape.

the roof over the attic is also made on the basis of wooden rafter trusses, however, its lower chord, which has support in the center of the load, can be lighter.

The optimal cross-section for rafters of any roof (as well as for floor beams) is 50x150 mm.

Distance between supporting roof structures
In wooden structures, the distance between the trusses is 0.9…1.0 m. With a large snow load on flat roofs, this distance should be reduced to 0.8…0.6 m, and on roofs with a slope of more than 45° it can be increased to 1.2…1.4 m. If the roof is erected with wooden rafter trusses, the lower chord of which are the beams of the attic or interfloor ceiling, then the distance between them should be taken into account the structure of the floor or ceiling. When constructing hipped and hipped roofs, lighter trusses and rafters can be used with smaller roof slopes than in gable roofs. A hipped roof assembled from ready-made wooden trusses (with a distance between them of 1200 mm) is shown in Fig. 1 and 2.

If the spans are too large, the width of the supporting surface of the trusses must be checked against the drawing and, if necessary, the distance between them must be reduced so that the calculated pressure on the supporting connection is not exceeded.

If a truss is located in a place where smoke pipes pass, it is moved and positioned so that it is at a distance of at least 100 mm from the pipe. The distance between the trusses, which turns out to be large in the place where a group of pipes pass, is filled with a solid grate.

The designs of one-piece and two-piece timber trusses are shown in Fig. 4. Two-piece trusses are used for long spans and when the house is on a slope and the roof has different levels.