Traditional Purlin Roof Construction

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.

Traditional purlin roof construction.

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. Sizes used in traditional roofing construction. There are three types of purlins in wood construction.

All the figures are based on roofing tiles or slates laid on. Purlin roofs and prefabricated roofs are the two common forms of roof structures. By chance we came across this roof a few miles outside bristol. At the eaves and halfway between the two where they are known as purlins.

Parts of a traditional queen post roof truss. The overall construction of a traditional cut roof is to ensure that the load of the roof is evenly transmitted to the walls below. 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. Roofs and not for traditional purlin and rafter roof construction.

The rafters are the main load bearing elements of the roof. They span from the wallplate to the ridge board providing a platform for the underlay battens and tiles. This house s roof construction used prefabricated trusses from turner timber. 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.

The traditional option is steeply pitched rarely less than 35. Here insulation is usually placed between the roof joists i e. Purlin plate principal purlin and common purlin. The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters.

Building control guidance note purlin and rafter roofs timber sizes and construction details. There are two basic methods of pitched roof construction. In traditional timber truss construction purlins rest on the principal rafters of the truss. Purlin plates under purlin principal purlins and common purlins.

Once the purlins are in place the panels can be craned in in a matter of minutes. In traditional timber framing there are three basic types of purlin. Pitched roof construction. Nowadays finding a traditional roof being constructed on a new building is quite difficult.