During the construction of a steel truss roof, which of the following statements are correct?
1. Steel truss transmits self-weight and roof loads vertically on the walls.
2. Spacing between steel trusses are usually between 10 feet to 15 feet.
3. Steel trusses use reduced dead load of building making structure unstable.

Correct option is A

Steel Roof Trusses:
Roof trusses are elements of the structure composed of members subjected to direct stresses. Sometimes the truss is also called an open web beam. It consists of a triangular network of compression and tension members.
Roof trusses are subjected to dead load, live load snow load, and wind load. Roof trusses transmitted these loads to the walls.
The spacing of roof trusses is kept 13 to 15 of the span. And generally varies from 10 ft to 15 ft.
They are economical spans more than 6 m.
The pitch of the roof should be  to 16 for proper drainage.
They are economical spans more than 6 m.