Load-bearing structures of pitched roofs

[zihadhosenjm40]

A variant of the hip roof (Fig. 120, g) is the so-called half-hip or half-gable roof. In this case, the side slopes cut off only part of the gable and, as a result, have a shorter length along the slope than the main slopes. The half-hip, located at the top, has the shape of a triangle.
The construction of the plan of the pitched roof (Fig. 121), which is a combination of several rectangles, is carried out, guided by the following rules:

with the same slope inclinations, all edges and valleys in chile mobile database plan must be directed along the bisectors of the angles formed by the intersecting cornice lines;
The ridge line of the roof should pass through the intersection point of the ribs and valleys.
Fig. 121 shows the construction of a roof plan, when a narrow building with a gable roof 3-5-6-7 is adjacent to a wide building with a hipped roof 1-2-3-4 and a ridge 9-10. The ridge of the roof of the narrow building is extended to the intersection at point 8 with the edge 3-9. By connecting points 8 and 5, we obtain a valley 8-5.

The supporting structures of pitched roofs are made of wood, steel and reinforced concrete in the form of rafters, rafter trusses and large panels.
The choice of material and type of supporting structure of the roof depends on the location of internal supports in the building, the size of the spans to be covered, the roof slope and special requirements for the roof in terms of fire resistance, durability and thermal properties.
The simplest type of supporting structure of pitched roofs of civil buildings are wooden sloping rafters. They are made of logs, beams, boards or plates to cover spans up to 14 m if the building has one internal support and up to 16 l with two internal supports.
The general appearance of sloping wooden rafters of a single-pitched and gable roof is shown in Fig. 122.
The simplest form of pitched roof rafters consists of rafter legs supported by purlins (mauerlats) laid over the outer walls (Fig. 123, a). The purlins serve to distribute the concentrated load transferred by the rafter leg over a significant area of ​​the wall and to prevent the lower ends of the rafters from rotting.
The distance between the rafters along the building (rafter pitch) is taken depending on the type of roof and the cross-section of the sheathing elements. Rafters made of 180-200 mm high beams are placed every 1.5-2 m, and rafters made of plates and boards - every 1-1.5 m. Sawn timber is mainly used for the construction of rafters.