Traditional Purlin And Rafter Roof Construction

There are three types of purlins in wood construction.

Traditional purlin and rafter roof construction.

Exposed rafters are a feature of some traditional roof styles. Traditional or cut roofs usually comprise a series of sloping timbers rafters fixed to a wall plate at their feet and a ridge board or possibly a wall plate at their head. Building with them is known as stick framing. The timbers are often 400mm or so centres and vary in size according to span.

The longitudinal horizontal beam that is sitting on a post or the principal rafter of a truss and used to support common rafters. Parts of a traditional queen post roof truss. With this layout the upper level which is typically framed construction rather than log the ceiling slash roof can use rafters and purlins to add log elements. Building control guidance note purlin and rafter roofs timber sizes and construction details.

50mm wide by 75mm 100mm or 125mm deep are all common. Through purlins pass over the top. This means that each rafter is built on the job site using dimensional lumber. With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel.

Every piece is measured cut and fastened together to form the rafter. Sizes used in traditional roofing construction. Using a combination of rafters and purlins is common. 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.

Whichever you choose the roof is then enclosed typically with tongue and groove lumber but increasingly with structural insulated panels sips which boost the home s energy efficiency. Butt purlins tenon into the sides of the principal rafters. This arrangement offers support for the roof adds interior aesthetic if you opt to match the rafters and purlins with the wall logs. And clasped purlins of which only one.

Purlin plates under purlin principal purlins and common purlins. Rafters are the traditional means of framing a roof. Principal purlins in wood construction also called major purlins and side purlins are supported by principal rafters and support common rafters in what is known as a double roof a roof framed with a layer of principal rafters and a layer of common rafters. Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and or the building walls steel beams etc.

This diagram shows the major components of a traditional rafter. In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof. All the figures are based on roofing tiles or slates laid on. 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.

There are two basic methods of pitched roof construction. The support system for the roof is comprised of ridgepole and rafters or purlins.