Purlins Of Flat Roofs

8 x section modulus of a 4 2 of 1 3125 x fb fiberstress in bending x 1 15 duration of load x 1 15 cr repetitive member factor as the purlins are spaced 24 o c.

Purlins of flat roofs.

Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. Purlins 24 spacing mike the pole barn guru writes. Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed for installation. 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.

Snap a chalk line horizontally across the roof two feet down from the top. Lay the first purlin at the ridge. Or less x 1 1 cfu the flat use factor for applying the load to the wide face of a member. Illustration shows purlins at 1 2m centres however the maximum purlin centres should not exceed 1 8m.

How to install metal roof purlins. Flat roofs the recent and more onerous requirements of approved document l of the building regulations relating to energy conservation have shifted the emphasis for thermal efficiency from the building structure to the building envelope. 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. If you are planning upon going with edgewise purlins across a single truss you are going to run into an uplift problem.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.