To help develop this article, click 'Edit this article' above.
Purlins are horizontal beams that are used for structural support in buildings. Most commonly, purlins are major components of roof structures. Roof purlins are supported either by rafters or building walls and the roof deck is laid over the purlins.
Traditional timber framing includes three basic purlin types; the common purlin, the purlin plate and the principal purlin.
Purlins can be made of a number of different materials and are available in a number of different types:
- C Purlins : The shape of these types of purlins is that of a square 'C'. C Purlins are used as Purlins over walls, rafters, floor joists and studs for walls.
- Z purlins : Z purlins resemble the alphabet Z and are also called as Zed Purlins. This shape helps the Purlins to overlap joint and is stronger and studier than the C purlins. As a result, they tend to be used for large-scale structures.
- RHS purlins : For roofs where the support structure is visible once the construction is complete, RHS Purlins may be used (Rectangular Hollow Section). These Purlins are basically hollow, rectangular tubes, with welded ends so there is no steel bar corrosion, damage or seepage.
Purlins are available in variety of materials depending on budget, structural and aesthetic requirements. The most traditional material for purlins is wood. However steel roof purlins and galvanized purlins can offer benefits of durability, cost and structural strength. Cold formed steel and the hot rolled steel processes can be used to create the required shapes from the steel sheets.
 External references
Featured articles and news
Government announces leaseholds on new-build houses will be banned.
Transport Secretary announces public consultation into London's funding of Crossrail 2.
Have a look at some of the most impressive concert stage designs of all time, including Pink Floyd, U2, Rolling Stones, and more...
What is the Home Quality Mark? Find out how it can help you when buying/renting a new home.
Business Secretary launches £246m Faraday Challenge to establish UK as world leader in battery technology.
Government announces new plans for regulations to improve safety and security awareness of drone users.
Read our introductory article to the various different types of fuel.
IHBC book review: Charles Barry’s monumental struggle to rebuild the Houses of Parliament.
Read about RSHP's British Museum extension which has been shortlisted for the 2017 Stirling Prize.
Read our introductory article to building a house extension.
More updates from DCMS about the large-scale testing of cladding systems and the number of buildings affected.
UandI secure resolution to grant planning consent for major new regeneration project.
It was the tallest structure in the world for 3,800 years, but to this day the exact construction techniques are a mystery.