Steel Rafter And Purlin Roof Construction

Purlins are installed horizontally under metal roofs.

Steel rafter and purlin roof construction.

Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building. Rafters shall be framed not more than 1 1 2 inches 38 mm offset from each other to ridge board or directly opposite from to each other with a gusset plate as a tie. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Note that these are normally only required to trussed rafter roofs and not for traditional purlin and rafter roof construction.

Ridge board shall be not less than 1 inch 25 mm nominal thickness and not less in depth than the cut end of the rafter. The typical spacing standards for residential and commercial buildings are about 1 to 2 foot. The purpose of purlins. These structural supports run perpendicular across the rafter beams.

This design is a lot stronger and more robust way of making a steel shed. The support system for the roof is comprised of ridgepole and rafters or purlins. Metal roofing panels rated for architectural use attached to purlins horizontal pieces of wood or metal fastened to roofing trusses are structurally sound when installed according to your roofing manufacturer s instructions and local building codes. An affordable option and easier to lay than shingles tin is the most commonly used type of metal roofing.

Metal c purlins are light in weight and perfect for simple span construction. For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet. Let s take a look at the most common types of metal roofs for houses. 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.

For many applications a layer of plywood underneath your metal roofing is an unnecessary expense. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. Whether you are looking to install a metal roof on a shed or a house it s important to know the difference in the various types of metal roofs available. Purlins are 2 by 4 feet and are installed much like metal roofing.

Purlins and girts are used longitudinally to support the roof sheeting which they were originally designed for. Rafters to support the metal strap along its whole. The steel purlins are in turn supported by rafters or walls. The rafter and wall plate.

Building control guidance note purlin and rafter roofs timber sizes and construction details. J l neal subject. 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. 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.