Fasten the purlin with 16d common nails into each vertical rafter.
Purlin shed roof.
Snap a chalk line horizontally across the roof two feet down from the top.
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.
The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed.
Metal building roof purlins provide three structural functions.
Purlin roof structure civil engineering design in architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof.
Insert two equally spaced nails into the rafter.
Purlins and girts are used longitudinally to support the roof sheeting which they were originally designed for.
First the purlins support the roof.
Lay the first purlin at the ridge of the roof down to the chalk line beginning at either corner.
Thirdly purlins add additional support between the spans of the individual framing bays.
Secondly purlins tie the rafters together stabilizing and strengthening the structure s rigid framing.