Civil Engineering Reference
In-Depth Information
Figure 8.17
Installation of underpurlin and struts to provide mid-span support of rafters
There are several different struts that all have legal requirements for their installation.
The perpendicular strut (see Figure 8.18) is to have a minimum bearing of 45 mm onto
the underpurlin and is to be fixed at approximately 90 degrees to the rafters. The vertical
strut (see Figure 8.19) is to have a minimum bearing onto the underside of the
underpurlin of 38 mm.
Figure 8.18
Perpendicular strut
Figure 8.19
Vertical strut
Intermediate support of rafters where there are no walls below
There are three primary methods of supporting the roof where there are no walls below
onto which struts can transfer the roof load from the underpurlins. The first is the
