House C Purlins Roof Design

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.

House c purlins roof design. Paul s cathedral in london. One reader suggests that this is inadequate. The c section can be supplied as a standard configuration or with the top flange bent to suit the roof slope. Purlins are 2 by 4 feet and are installed much like metal roofing.

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. In the past the majority of roof structures were of wooden construction but over the past 15 to 20 years there has been a vast shift away from wood to metal mainly steel roof construction. Of a fascia purlin in fascia applications. The plane surface of c purlin on its one side has made it a preferred material for cladding due to its easy installation on concrete structures or steel.

They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Purlins are 2 by 4 feet and are installed much like metal roofing. 20 95 30 d c a b variable angle 18 x 22 holes 34 x 10 recess upturned lip z sections standard z the following diagrams and tables illustrate the sizes and thicknesses readily available for. The trusses are welded to stubs of rebar protruding through and well anchored in the concrete roof beam.

Purlins are installed horizontally under metal roofs. How to design c purlins and sag rods design according to nscp 2015 c purlins are horizontal type steel section that are used to support the load from the roof deck or the sheathing. Purlins traditionally support the roof deck cladding sheeting and are in turn supported by the principal rafters steel beams etc. A complex and durable design this type of roof adds a beautiful aesthetic to a building and can be seen in many historical buildings from the capitol building in washington d c to the iconic st.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Metal roof purlins are installed horizontally under metal roofs. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. As structural members they resist loads and provide lateral restraints for truss members therefore it is important to design them properly against forces.

Do all roofing projects require purlins.