Rafters are the sloping structural members that support a pitched roof covering. They run from the ridge or hip down to the eaves, where they usually bear on a wall plate.
In a traditional cut roof, rafters are cut and fixed on site by carpenters, often with purlins, binders and ceiling joists providing support and restraint. Many modern houses use factory made trussed rafters instead, which are quicker to install but leave little usable roof space. Types of rafter include:
- common rafters, the main members running from ridge to eaves
- hip and valley rafters, which form the external and internal angles where two roof slopes meet
- jack rafters, shorter members that run between a hip or valley rafter and the eaves or ridge
For measurement, rafters are generally measured by length with the cross section stated, so that the timber can be priced accurately.
Related terms: ridge, trusses, purlin, wall plate.
