Rafters have a tendency to flatten under gravity thrusting outwards on the walls.

Timber roof structure elements. A timber roof truss is a structural framework of timbers designed to bridge the space above a room and to provide support for a roof. For larger spans and thinner walls this can topple the walls. Finishes for flat roofs are also more limited. The roof shown on the right is the same in principle although there is an additional timber known as a purlin which prevents the rafters from sagging mid span.

Roof framing in this chapter we will introduce you to the fundamentals of roof design and construction. Timber trusses are exposed to warping and bowing problems which can cause structural damage to the rest of the building. The roof also depend on its trusses for it shape. A top plate is nailed to the top of wall studs.

But this type of roof is seldom as attractive as the pitched form as it can result in a blocky stunted appearance. Trusses usually occur at regular intervals linked by longitudinal timbers such as purlins the space between each truss is known as a bay. There are two basic components of a timber roof. To achieve this is a simple frame called a ladder frame is constructed.

This is the plate that the roofing elements sit on and effectively the meeting point of the walls and the roof structure. Trusses usually occur at regular intervals linked by longitudinal timbers such as purlins. But before discussing roof framing we will first review some basic terms and definitions used in roof construction. The space between each truss is known as a bay.

A truss is a piece of framework using triangular shapes. Timber trusses generally cheaper than steel trusses wooden trusses don t last as long because timber being a natural material cannot stand up to the elements as well as steel. Roof structures roofs 12section module 3 sheet 10 verge details and ladder frame the construction of the verge of a gable roof is shown below. Pairs of opposing rafters were thus initially tied together by a horizontal tie.

It supports the roof load and helps transfer it down load bearing walls and into the foundations. Are designed to be part of a structural system that includes the battens bracing trusses binders ceiling supporting structure and the connection of these elements. Safety on site using timber engineered components floor trusses wall frames and roof trusses etc. Roof trusses can be said to be the skeleton of the roof as you known the skeleton produce the shape of animals even humans.

For homebuilders a timber frame for a flat roof is usually the cheapest option and the easiest to build. The roof extends over the gable wall to give a suitable overhang. The purlin is supported by the gable end walls party walls in mid terraced houses and is sometimes strutted from an internal loadbearing wall and sometimes the gable walls to a provide additional support. The supporting structure and the covering.

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