Traditional Purlin Roof Construction

The beams will typically be placed along the ridge at the eaves and halfway between the two where they are known as purlins.

Traditional purlin roof construction.

In domestic construction it typically comprises a series of rafters fixed to walls at either end of the roof span which support battens to which the roof covering is fixed. Every member of a traditional cut roof is individually cut and assembled on site. Roofs and not for traditional purlin and rafter roof construction. 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.

The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters. They span from the wallplate to the ridge board providing a platform for the underlay battens and tiles. For more information see mono pitch roof. In traditional construction spans of over 3 metres or so were often dealt with by adding a purlin.

Building control guidance note purlin and rafter roofs timber sizes and construction details. There are three types of purlins in wood construction. In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof. Once the purlins are in place the panels can be craned in in a matter of minutes.

This is a large timber running at right angles to the rafters and usually positioned mid span. There are two basic methods of pitched 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. A common arrangement is a rafter and purlin system which combines purlins and rafters.

Common purlins in wood construction also called a major rafter minor purlin system. Sizes used in traditional roofing construction. All the figures are based on roofing tiles or slates laid on. The use of purlins as opposed to closely spaced rafters is common in pre engineered metal building systems and both the ancient post and beam and newer pole building timber frame construction methodologies.

It is a very common form of construction. A truss roof using factory made trusses which are delivered to site complete and just erected. Sips panels these panels are from sipco need to be craned into place. Common purlins are typically trenched through the top sides backs of principal rafters and carry vertical roof sheathing the key to identifying this type of roof system.

Parts of a traditional queen post roof truss. The rafters are the main load bearing elements of the roof. Purlin plates under purlin principal purlins and common purlins.