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.
Purlin metal roof structure.
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 purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.
First the purlins support the roof.
In structural steel or aluminum construction p urlins usually w shapes or channels transfer roof loads to the major structural elements supporting the roof.
The purlins are in turn supported by rafters or walls.
Purlins are most commonly used in metal building systems where z shapes are utilized in a manner that allows flexural.
Purlins are 2 by 4 feet and are installed much like metal roofing.
Metal building purlin spacing.
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.
Welded together they can be used as columns braces and ties.
Thirdly purlins add additional support between the spans of the individual framing bays.
We do recommend it however.
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.
Purlins and girts are used longitudinally to support the roof sheeting which they were originally designed for.
The shape of cee purlins does not allow end lapping they are butted together.
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.
Secondly purlins tie the rafters together stabilizing and strengthening the structure s rigid framing.
Metal building roof purlins provide three structural functions.
In a structural steel shed the main portal frames and roof rafters are made from strong steel sections which are welded together and later bolted together.
In steel construction the term purlin typically refers to roof framing members that span parallel to the building eave and support the roof decking or sheeting.
Also referred to as secondary structurals this type of framing runs in between primary framing elements creating a structure within a structure much like cross beams in a wooden building.
Metal roofs are often referred as tin roofs in the past because of the use of tin such as aluminum or stainless steel sheets as the materials.
They give added support to the roof and also provide a nailing surface for the end panels and drip edge.
Compared to conventional roofing system it might be a bit pricier in terms of installation but also has longer durability to provide better value for the future.
