Structural Timber Flat Roof Construction Details

Sizes of joists needed for flat roof construction.

Structural timber flat roof construction details. Timber flat roof construction usually consists of structural joists topped with a decking of plywood or a similar sheet material. As part of the drive to deliver sustainable materials and energy efficient buildings the sta provides best practice guidance for its members. The emphasis of the article is on repair and reinforcement options including the use of scarf repairs stainless steel flitch plates and the use of resins. The ceiling will usually be fixed directly to the underside of the joists.

Wherever possible joists should span the shortest distance of the roof plan. Corbel conservation s robin russell provides an introduction to structural timber repairs in historic buildings. The article concludes with a section outlining approaches to the problem of roof spread. The structural relationship between the rafters and the wall is the same in all types of roofs.

So any timber joists that are used need to be strong enough to support this weight. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. Parts of both the walls and the roof. The pitch is governed by the roof covering and the required rate of rainwater discharge.

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. Part b structure investigates the structural aspects of flat roofs. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. An example of each is shown in figure 2 1.

Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. The most commonly used types of pitched roof construction are the gable the hip the intersecting and the shed or lean to. 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. The construction of the flat roof is similar to that of the timber upper floor.

The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. This mostly takes the form of timber based boarding of some type which in turn is supported on joists. In a flat roof the waterproofing is always supported by a structural roof deck. That will help you remember certain factors and details to build the best possible flat roof.

Old asbestos roofs are often replaced with flat roofs.