What is a purlin used for?


A purlin is used to support the rafters between the plate and the ridge of a roof. A purlin is a horizontal or longitudinal member in a roof frame.

There are several different types of purlins used in roof construction. An under purlin sits on the principal rafter of a truss or is propped off a wall to support the rafters. This type of purlin allows a longer span than the rafters alone are capable of spanning. An over purlin sits on the rafters or on a truss or a steel member to which the roofing material is directly attached. There are also several categories of purlins used in wood construction, including through purlins that pass over the top of the principal rafters and butt purlins that tenon into the sides of the principal rafters.

Q&A Related to "What is a purlin used for?"
Purlins are commonly used to support roofs. Purlins are horizontal in shape; it commonly supports rafters that hold up the roof. Thus purlins are quite heavy.
Flat roof? You can use standard trusses, hand cut trusses or attic trusses but they all achieve basically the same effect. Just grapsing at straws here though.
It wouldn't be that difficult but the load paths down through the structure would be very difficult so it would depend on the super stucture below.
Roof purlins, the wood strips used to tie roof trusses together and provide a point of attachment for roofing materials, are typically made from two by four lumber, spaced two feet
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Roof purlins can be described as horizontal structures in a building. They support the loads from the roof deck, they are supported by either rafters, buildings ...
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