Flat Roof Timber Frame Construction

Having a manual for warm flat roof construction with details and a summary of rules to follow helps.

Flat roof timber frame construction. Timber roof designing buildings wiki share your construction industry knowledge. Framing in construction is the fitting together of pieces to give a structure support and shape. The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal however some in the industry would consider up to 15 o as their definition of a flat roof. So any timber joists that are used need to be strong enough to support this weight.

Sizes of joists needed for flat roof construction. Framing materials are usually wood engineered wood or structural steel the alternative to framed construction is generally called mass wall construction where horizontal layers of stacked materials such as log building masonry rammed earth adobe etc. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off.

Old asbestos roofs are often replaced with flat roofs. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. A cavity closer should be provided to the top of the walls to prevent fire spread and to stop damp air entering the roof space.

The construction of the flat roof is similar to that of the timber upper floor. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. For additional stability you can also use steel joists that are built into one or both of the walls. Where a new flat roof abuts an existing external wall the joists can be hung on metal joist hangers which are fixed to a horizontal timber plate wall bolted to the wall.

Are used without framing. 3 06 timber frame timber flat roof 3 07 timber frame timber flat roof with parapet 3 08 timber frame lintel at window head 3 09 timber frame windows and doors jambs and cills specification within an example should 3 10 timber frame ground bearing floor insulation above slab 3 11 timber frame ground bearing floor. Others would treat even steeper pitches as flat roofs.