In wooden frame buildings, the most common roof structures are rafter trusses or trusses made of combined elements. The plank trusses are very light, do not burden the house structure too much.
The base of the plank truss is called the bottom chord. Top chords are the equivalents of rafters. The top straps and the bottom straps form a kind of frame, filled with posts and diagonals, i.e. elements stiffening the structure.
As a standard, truss trusses are used in the construction of unused roofs – uninsulated, with thermal insulation at the level of the lower truss chord, however, they can also be used to construct roof structures with an attic. Most often these are mansard roofs.