Flat Timber Roof Construction Details

Usually a flat roof is built with a slight slope to provide some drainage.

Flat timber roof construction details.

Applying a liquid waterproofing agent will often add a few more years to the roof. Others would treat even steeper pitches as flat roofs. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. Flat roofs became popular amongst early 1900s modernist architects because they removed the often complicated pitched roofs of traditional construction and replaced them with perfect straight lines.

If your flat roof is beginning to resemble a patchwork quilt then it s time to consider a more extensive treatment with your timber flat roof construction details. The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. For additional stability you can also use steel joists that are built into one or both of the walls.

Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. 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. On a basic level flat roof construction comes in the form of roofing timbers or joists as they are more commonly known or steels that are laid across two uprights walls in most cases. Flat roofs aren t actually flat but must slope to drain water.

The construction of the flat roof is similar to that of the timber upper floor. 3 05 timber frame pitched roof. 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.

This will give additional stability to the roof structure. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. These lines gleamed against the sky in the same way as other products of industrialisation such as trains. They used modern materials such as steel glass and concrete to rationalise their buildings and searched for design ideas that represented this rationale through the form of the building.

A popular method involves a cold application bitumen emulsion which is applied onto the surface. Normally a slope of inch per foot is used. Ventilated batten void warm roof gable 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.