Traditional Purlin Roof Construction

A truss roof using factory made trusses which are delivered to site complete and just erected.

Traditional purlin roof construction.

The overall construction of a traditional cut roof is to ensure that the load of the roof is evenly transmitted to the walls below. A cut roof this is the traditional method of cutting the timber on site and building up the roof using rafters ridge boards joists and purlins etc the exact details being determined by the size of roof size of timbers etc. The rafters are the main load bearing elements of the roof. Exposed rafters are a feature of some traditional roof styles.

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. Parts of a traditional queen post roof truss. The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters. Nails bolts and screws create a mechanical fixing to stop uplift through wind etc.

Purlin 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. There are three types of purlins in wood construction. Sips panels these panels are from sipco need to be craned into place. There are two basic methods of pitched roof construction.

In traditional construction spans of over 3 metres or so were often dealt with by adding a purlin. Purlin plates under purlin principal purlins and common purlins. It is a very common form of construction. 3 lean to roofs less common.

A common arrangement is a rafter and purlin system which combines purlins and rafters. This is a large timber running at right angles to the rafters and usually positioned mid span. 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. Traditional roofs work by distributing loads from the rafters down through to the wall plate and then through to the walls below.

The best way to transfer load is with a timber to timber joint a compression fixing. Purlin plate principal purlin and common purlin. Every member of a traditional cut roof is individually cut and assembled on site. Once the purlins are in place the panels can be craned in in a matter of minutes.

In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof. In architecture structural engineering or building a purlin is any longitudinal horizontal structural member in a roof except a type of framing with what is called a crown plate. In traditional timber framing there are three basic types of purlin.