Rafter

In recent buildings there is a preference for trussed rafters on the grounds of cost, economy of materials, off-site manufacture, and ease of construction, as well as design considerations including span limitations and roof loads (weight from above).

The earliest surviving roofs in Europe are of common rafters on a tie beam; this assembly is known as a "closed couple".

It is necessary always to order this special bill of rafters direct from the mill, and the result will be that the extra cost will, nine times out of ten, overbalance the amount saved.

[4] A piece added at the foot to create an overhang or change the roof pitch is called a sprocket, or coyau in French.

The projecting piece on the gable of a building forming an overhang is called a lookout.

Common rafters without collar beams form most of this roof. There is not always a ridge board or beam where the rafter tops meet. Under the midsections of the rafters are purlins which support the common rafters and are supported by principal rafters. This roof ends in an octagonal hip.
A double roof (using a Norman truss), common rafters supported by principal rafters ( top chords in this case) and an unusual extra layer of common rafters on the lower half to form a gallerie. Note how the rafter poles for the gallerie tie-in. The Bequet-Ribault House was built c. 1793 near Ste. Geneviève, Missouri . It is one of five poteaux-en-terre buildings that survive in the US. [ 1 ]
Rafter and tie-beam joints (Carpentry and Joinery, 1925)
Coyau or sprocket. Labeled A