Traditional Rafter And Purlin Roof Construction

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

Traditional rafter and purlin roof construction.

Types of roof trusses. Building control guidance note purlin and rafter roofs timber sizes and construction details. 3 lean to roofs less common. The collar ties and hangers are used to improve the overall strength and stability of the roof.

These are normally only required to trussed rafter roofs and not for traditional purlin and rafter roof construction. Installation of purlins is quite an easy task. A common arrangement is a rafter and purlin system which combines purlins and rafters. In traditional timber truss construction purlins rest on the principal rafters of the truss.

A rafter is one of a series of sloped structural members that extend from the ridge or hip to the wall plate downslope perimeter or eave and that are designed to support the roof deck and its associated loads. The collar ties are used to connect the rafters preventing them from spreading outwards. 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. In traditional construction spans of over 3 metres or so were often dealt with by adding a purlin.

There are three types of purlins in wood construction. These rafters thus form the basis of a wider building. 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. Purlin plates under purlin principal purlins and common purlins.

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 main difference between rafter and purlin is that the rafter is a structural members in architecture and purlin is a structural member in a roof. Homes with gambrel roofs. The purlins made of steel can be easily cut with nibbler however it be any material all of them requires traditional form of fixing such that it can remain steady for many years to come.

The purlins are supported by struts which in turn are supported on an internal load bearing wall. Video of traditional cut roof detail. There are two basic methods of pitched roof construction. Common purlins in wood construction common purlins in wood construction also called a major rafter minor purlin system.

The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters. All the figures are based on roofing tiles or slates laid on. 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. It is a very common form of construction.