There are three types of purlins in wood construction.
Traditional rafter and purlin roof construction.
Pitched roof construction.
Sizes used in traditional roofing construction.
The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters.
A common arrangement is a rafter and purlin system which combines purlins and rafters.
8 simple purlin roofs.
All the figures are based on roofing tiles or slates laid on.
The overall construction of a traditional cut roof is to ensure that the load of the roof is evenly transmitted to the walls below.
These are normally only required to trussed rafter roofs and not for traditional purlin and rafter roof construction.
7 simple traditional roofs.
By supporting the rafters they allow longer spans than the rafters alone.
This is the right way to fix truss clips connecting the rafter and wall plate.
In architecture structural engineering or building a purlin or historically purline purloyne purling perling is any longitudinal horizontal structural member in a roof except a type of framing with what is called a crown plate.
Purlin plates in wooden construction.
10 complex new roofs.
Traditional or cut roofs usually comprise a series of sloping timbers rafters fixed to a wall plate at their feet and a ridge board or possibly a wall plate at their head.
A cut roof this is the traditional method of cutting the timber on site and building up the roof using rafters ridge boards joists and purlins etc the exact details being determined by the size of roof size of timbers etc.
A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin.
9 complex purlin roofs.
Purlin plates under purlin principal purlins and common purlins.
11 some examples of older traditional roofs.
The rafters are the main load bearing elements of the roof.
There are two basic methods of pitched roof construction.
The roof support system is a ridgepole and either rafters which run perpendicular from the top of the walls to the ridge or purlins which run parallel to the ridge.
They span from the wallplate to the ridge board providing a platform for the underlay battens and tiles.
Building control guidance note purlin and rafter roofs timber sizes and construction details.
Parts of a traditional queen post roof truss.
Note that these are normally only required to trussed rafter roofs and not for traditional purlin and rafter roof construction.