Traditional Purlin Roof Construction

Building control guidance note purlin and rafter roofs timber sizes and construction details.

Traditional purlin roof construction.

Parts of a traditional queen post roof truss. At the eaves and halfway between the two where they are known as purlins. They also provide a speedy construction reduce onsite labour and costs and are most importantly versatile and provide a form of flexibility as they tend to have the capacity for a wide range of roof coverings. In traditional timber framing there are three basic types of purlin.

The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters. Pitched roof construction. Traditional or cut roof. The traditional option is steeply pitched rarely less than 35.

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. This house s roof construction used prefabricated trusses from turner timber. The alternative construction is the traditional cold deck. The overall construction of a traditional cut roof is to ensure that the load of the roof is evenly transmitted to the walls below.

Once the purlins are in place the panels can be craned in in a matter of minutes. Since warm moist air is able to meet cold timber care must be taken to ventilate the roof void to minimise condensation and the possibility of rot. Here insulation is usually placed between the roof joists i e. Purlin roofs and prefabricated roofs are the two common forms of roof structures.

There are three types of purlins in wood construction. Purlin plates under purlin principal purlins and common purlins. The rafters are the main load bearing elements of the roof. All the figures are based on roofing tiles or slates laid on.

Sizes used in traditional roofing construction. It s an l shaped house with two very different roofs one is a collar roof the other a purlin roof with rsjs forming the purlins see photos below. Nowadays finding a traditional roof being constructed on a new building is quite difficult. In traditional timber truss construction purlins rest on the principal rafters of the truss.

Roofs and not for traditional purlin and rafter 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. By chance we came across this roof a few miles outside bristol. Purlin plate principal purlin and common purlin.