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What Is Rafter And Purlin

Nov 24, 2017

What is rafter and purlin?

Steel purlins and rafters are the basic members of steel roof structure,which are working as load transmitting components for steel roof system.Both of steel purlins and rafters could transmit live load,dead load and wind load,which could be main members in large steel structures with low permiability.And other loads of them is acting on combineing with the roof truss situated below them,which eventually transfers the load to steel columns and then evenualy to foundation.

In conclusion,purlin and rafter are just like two different ways of reinforcements for roof.Steel Purlins are parallel to ridge line,same as saying they run along the span of roof,but rafters are perpendicular (plan) to the ridge line of roof truss .

Pictures for you to divide difference between rafter and purlins: