Traditional Purlin Roof Construction

In traditional timber framing there are three basic types of purlin.

Traditional purlin roof construction.

Purlin plate principal purlin and common purlin. Parts of a traditional queen post roof truss. All the figures are based on roofing tiles or slates laid on. At the eaves and halfway between the two where they are known as purlins.

Pitched roof construction. The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters. There are three types of purlins in wood 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. Purlin roofs and prefabricated roofs are the two common forms of roof structures. Roofs and not for traditional purlin and rafter roof construction. Here insulation is usually placed between the roof joists i e.

Building control guidance note purlin and rafter roofs timber sizes and construction details. For example an 8 x 4 under purlin would support the center of a row of 6 x 2 rafters that in turn would support 3 x 2 roof purlins to which the roof cladding was fixed. In traditional timber truss construction purlins rest on the principal rafters of the truss. By chance we came across this roof a few miles outside bristol.

The traditional option is steeply pitched rarely less than 35. 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. The alternative construction is the traditional cold deck.

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. Once the purlins are in place the panels can be craned in in a matter of minutes. 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. Traditional or cut roof.

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. Purlin plates under purlin principal purlins and common purlins. The overall construction of a traditional cut roof is to ensure that the load of the roof is evenly transmitted to the walls below.