Rafter And Purlin Roof Construction

Secondly purlins tie the rafters together stabilizing and strengthening the structure s rigid framing.

Rafter and purlin roof construction.

A common arrangement is a rafter and purlin system which combines purlins and rafters. Depends in domestic construction in australia and the uk a purlin is a horizontal timber member that holds the rafters up mid span. Thirdly purlins add additional support between the spans of the individual framing bays. First the purlins support the roof.

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. Los angeles building code 23 wood 2308 conventional light frame construction 2308 7 roof and ceiling framing 2308 7 7 purlins r802 5 roof ceiling construction allowable rafter spans installation of purlins to reduce the span of rafters is permitted as shown in figure. Civil engineering design in architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof. The roof framing modification factors shall take into consideration the climatological location.

Purlins shall be continuous and shall be supported by 2 inch by 4 inch 51 mm by 102 mm. 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. R802 1 5 8 exposure to weather. The steel purlins are in turn supported by rafters or walls.

There are two basic methods of pitched roof construction. In architecture structural engineering or building a purlin or historically purline purloyne purling perling is any longitudinal horizontal structural member in a roof except a type of framing with what is called a crown plate. Metal building roof purlins provide three structural functions. The rafters then hold up battens which hold the roof fabric typically tiles or steel sheeting.

The roof support system is a ridgepole and either rafters which run perpendicular from the top of the walls to the ridge or purlins which run parallel to the ridge. Purlins shall be sized not less than the required size of the rafters that they support.