Purlins Of Flat Roofs

Trusses most likely on 8 s.

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. If you are planning upon going with edgewise purlins across a single truss you are going to run into an uplift problem. Or less x 1 1 cfu the flat use factor for applying the load to the wide face of a member. Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed for installation.

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. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Roof live load roof dead load x spacing x span of purlin 2 divided by. Snap a chalk line horizontally across the roof two feet down from the top.

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 placed flat will not span eight feet so eliminates this option. How to install metal roof purlins. Illustration shows purlins at 1 2m centres however the maximum purlin centres should not exceed 1 8m.

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.