Steel Purlin Flat Roof

Insert two equally spaced nails into the rafter.

Steel purlin flat roof.

Lay the first purlin at the ridge of the roof down to the chalk line beginning at either corner. Engineered purlin metal mart offers a complete line of engineered purlin material. 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. Illustration shows purlins at 1 2m centres however the maximum purlin centres should not exceed 1 8m.

The purlins have to be able to support their own weight of about 0 5 psf pounds per square foot plus the steel 0 63 psf. Available in cee or zee shape red oxide primed or galvanized 16 14 or 12 gauge sizes from 4 up to 12 flange widths of 1 1 2 up to 4 cut to your specified lengths hole punching available load tables available for all material. 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. With the slope of the roof the live load can be reduced using the cosine of the roof slope 0 949 to get the applied load of 18 98 psf.

As the roof live load of 20 psf is being carried by members 24 o c. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Fasten the purlin with 16d common nails into each vertical rafter. Do all roofing projects require purlins.