Question

When the span exceeds 4.8 M and when there is no inside supporting walls for Purlins, the frame structures adopted, known as the _____________

(a) Single roofs

(b) Purlin roofs

(c) Double roofs

(d) Trussed roofs

Answer 1

Correct choice is (d) Trussed roofs

The explanation is: The spacing of Trusses depend upon the load on the roof, position of cross walls, span and materials on the trust. But the spacing is generally 3M for wooden Trusses. The Trusses carry the ridge pieces and Purlins on which the common rafters rest.