Purlins are installed horizontally under metal roofs.
Roof framing plan roofing c purlins.
Purlins traditionally support the roof deck cladding sheeting and are in turn supported by the principal rafters steel beams etc.
Besides providing support for the roof rafters and purlins add to the interior beauty so you often see log purlins and rafters that match the wall logs.
A common arrangement is a rafter and purlin system which combines purlins and rafters.
Welded together they can be used as columns braces and ties.
In addition our c section purlins can also be used for door framing roof trimming window trimming parapet rails and side rails also see z purlins page.
A traditional purlin strictly by definition is a horizontal structural member in a roof.
They give added support to the roof and also provide a nailing surface for the end panels and drip edge.
Purlins are 2 by 4 feet and are installed much like metal roofing.
Engineered purlin metal mart offers a complete line of engineered purlin material.
In small roofs purlins are inserted between the rafters and nailed through the rafters.
We do recommend it however.
In structural steel or aluminum construction purlins usually w shapes or channels transfer roof loads to the major structural elements supporting the roof.
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.
The type and spacing of purlins is a design consideration which depends upon the incident roof loads as well as the limiting lengths of sheeting to be used.
Dead load will be the actual weight of the roof steel and the roof purlins.
For sake of discussion we will assume a minimal roof snow load of 20 psf pounds per square foot and a 4 12 roof slope.
C section purlins or cee section purlins are designed to form the walls and floor joists of a building shell structure making them also ideal for supporting beams needed for mezzanine flooring.
Cee purlins are secondary steel framing members most commonly used as roof purlins wall girts and header jamb and sill for windows and doors on metal buildings.
The cos of the purlin spacing is because the load on the purlins is vertical and the purlin spacing is with the run of the roof.
Purlins purlins are used in roof construction to support corrugated sheet metal if it is used or to support the sheathing of roofs framed with trusses.
They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top.
Do all roofing projects require purlins.
The shape of cee purlins does not allow end lapping they are butted together.
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.
The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.
