Roof trusses refer to the frames made up of timber that is nailed, bolted or pegged together to form structurally independent shapes of great strength. The truss is used to bear the weight of the roof timbers and coverings, and the occasional wind load and snow load. These trusses come in all shapes and sizes to adapt the various designs of the roof. Trusses are used to preventing the walls from bending or flexing, and more important for buildings and homes with several stories.

These trusses mainly have three properties, the strength of timbers, the distribution of the load, and the connection of the parts. The trusses have been treated specially to prevent the insect, so the modern trusses usually weight slightly. The design of roof trusses is important, and the structure of the trusses can elaborately assign the load to prevent gathering the whole load in some small area. Wind loading , such as bolt, plates, nails, screws and even nails can be used to connected the parts, but make sure the structure is stable.

Some problems should be paid more attention to prevent the adversity happen. The penetrating damp is the most critical problem, and older buildings are more susceptible. Some preservatives including Boron are helpful to solve this problem. The rot and insect attacking is also a serious problem, which mainly exist in the older properties, the Boron based preservatives are also useful. In addition, joint areas tend to destroy easily, and rein repair can solve this problem.