The structural behavior of each member in a timber truss is different from that of a solid-timber beam. A downward load applied along the length of a beam will cause it to bend, but such a load applied to a truss generates tension or compression that is shared by each of its members in concert. Even if one truss member acts as a column, the overall truss still acts as a unit. For that reason, a truss can be lighter than a beam for a given span and load. Also, the rate at which member weight rises with increasing span is generally lower with a truss than with a beam.
Fasteners require holes, grooves, or recesses.
These voids reduce the structural capacity of the member. The fasteners with the greatest structural capacity require the largest holes. As a result, such connections often control the design of the truss, necessitating the use of larger timbers if there are multiple voids required in the wood. Fasteners that require fewer holes are recommended wherever the objective is to minimize the size of the member. The shapes of trusses are a function of the shape of the roof.