Roof Purlin Deflection

Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and or the building walls steel beams etc.

Roof purlin deflection.

Allowable deflection is generally expressed as a fraction of the span in inches. An example is air conditioning put on top of a roof this may well minimize wind uplift whilst increasing dead load downwards. Another issue can arise when homeowners unknowingly remove struts and collars in their loft to create extra space for storage again this will cause roof deflection. All structural members will deflect or flex under load.

Butted purlin system butted connection roof sag system roof angle brace system mono pitch roofs steep pitch roofs shallow pitch roofs long roof slopes curved roofs tiled roofs cantilever purlins introduction zed and cee section range overview product range page 1 sections eaves beam details typical connections. The use of purlins as opposed to closely spaced rafters is common in pre engineered metal building systems and both the ancient post and beam and newer pole building timber frame construction methodologies. Image copyright belongs to albion sections limited uk roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel. In timber construction purlins are nailed to the rafter or supporting trusses while in steel roof construction they are welded or bolted to the rafters or trusses by the means of cleats.

The amount of flex depends on the magnitude of the load applied span of the member and stiffness of the member. In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof.