Structural Timber Flat Roof Construction Details

The construction of the flat roof is similar to that of the timber upper floor.

Structural timber flat roof construction details. A roof is defined in bs 6229 as a flat roof if it has a pitch of 10 degrees or less. Modern timber roofs are mostly framed with pairs of common rafters or prefabricated wooden trusses fastened together with truss connector plates timber framed and historic buildings may be framed with principal rafters or timber roof trusses roofs are also designated as warm or cold roof depending on how they are designed and built with regard to thermal building insulation and ventilation. The structural relationship between the rafters and the wall is the same in all types of roofs. Timber flat roof construction usually consists of structural joists topped with a decking of plywood or a similar sheet material.

An example of each is shown in figure 2 1. The structural timber association sta is the membership body which promotes the use of structural timber and hybrid forms of timber construction such as structural insulated panels sip in buildings. Sizes of joists needed for flat roof construction. Flat roof types.

Wherever possible joists should span the shortest distance of the roof plan. So any timber joists that are used need to be strong enough to support this weight. That will help you remember certain factors and details to build the best possible flat roof. The most commonly used types of pitched roof construction are the gable the hip the intersecting and the shed or lean to.

Part b structure investigates the structural aspects of flat roofs. Old asbestos roofs are often replaced with flat roofs. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. Others would treat even steeper pitches as flat roofs.

The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. The pitch is governed by the roof covering and the required rate of rainwater discharge. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. Having a manual for warm flat roof construction with details and a summary of rules to follow helps.

A flat roof must be strong durable and stable throughout its lifetime. The rafters are not framed into the. Besides the various loads acting on the flat roof the chapters of this section discuss potential primary structures and. It must provide adequate protection against the elements keeping the buildings structure and interior dry.

Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. Parts of both the walls and the roof.