Construction services

Roofs with a collar beam structure

tmp38a4-1A roof truss of a collar beam structure with two cap beams.

The hose is a beam that braces two rafters. In a collar beam structure, each pair of rafters is connected with a collar on the so-called. half cave tail.
Depending on the length, the collar may or may not require support with cap beams based on columns. And so accordingly:

– length up to 3,5 m do not require support,
– length collar 7,5 -10 m are supported by one girder,
– length collar 9 -12 m are supported by two gussets.

If the attic is intended for residential purposes, collar beams are used as beams of the ceiling above the attic.
In order to stiffen the girders, additional purlins can be used above the collar bars (at the junction with the rafters).
The mayopies primarily act as struts, therefore the entire roof load is transferred to the outer walls. This requires anchoring the wall laths and securing the knee walls against sliding apart.