For spans over 6 m, as well as for heavy snow loads

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In single-story, single-span houses up to 6 m wide, roofs can be erected using the simplest wooden rafter trusses knocked together from 50 x 150 mm boards. They are easy to make in advance, laying one on top of the other, and then installed, fastened with diagonal wind ties from the inside. The rafters and the lower chord (tie) are connected to each other with nails or screws using double-sided overlays made of 25 mm thick boards.

Fig. 3. Structural diagrams and units of gable plank roofs:
a, b — hanging rafters (wooden trusses) for single-story single-span buildings;
c — inclined rafters for single-story two-span buildings;
g — hanging rafters (wooden trusses) for attic single-span buildings;
d — the same with a pitched roof;
e — the same for attic two-span buildings.

The wooden rafter truss must be reinforced with china mobile database internal braces. For design reasons, it is more convenient to make it with double lower and upper chords. In this case, all elements of the truss (rafters, tie, braces and end inserts) can be made of boards of the same thickness. The places where the braces adjoin the upper and lower chords, as well as the joint of the tie boards, should be reinforced with plank overlays. It is better to connect individual elements of such trusses with screws or bolts.

The use of large-span wooden rafter trusses in single-story houses allows you to abandon the construction of a middle load-bearing wall (along with foundations) and get a free interior layout in the house. At the same time, it should not be forgotten that the use of such trusses can only be recommended with competent design and careful execution of preparatory and installation work.

For single-story two-span buildings (with a central load-bearing wall), a gable roof is usually made using rafters with one end resting on the outer wall and the other on the purlin or central posts. At the ridge, the rafters are joined together with overlapping nails or with the help of plank linings. If the rafter legs are longer than 4 m, struts are installed. The outer ends of the rafters are supported by a backing distribution beam (mauerlat) with a cross-section of at least 100x100 mm. For ease of support, a stop block is nailed to the bottom of each rafter. Every second rafter leg is fastened to the outer wall or to the attic beams with wind ties (wire clamps, plank linings).

Roofs in houses with attic rooms in the absence of a central support are structurally solved in the same way as rafter wooden trusses. A kind of tightening of such trusses are the beams of the interfloor overlap, against which the rafters rest. The simplest design of a mansard roof is a triangular wooden truss of a rectilinear outline, used in the construction of an attic in single-span houses up to 6 m wide. Considering that the lower belt of such a truss is the floor of the attic, its design is taken in the form of two parallel beams with a cross-section of at least 50x150 mm each. Horizontal grips and vertical posts are also better made in pairs from thinner boards - this simplifies the further cladding of the walls and ceilings of the attic.