Timber Flat Roof Construction Details

A roof which is approximately flat is called as a flat roof.

Timber flat roof construction details.

The roofs have a timber frame as the supporting structure. A timber decking is then constructed and its weight supported by the joists. For additional stability you can also use steel joists that are built into one or both of the walls. Flat roof joists spanning the shorter length of the roof form the load bearing members of the structure.

Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. The joists are attached to load bearing walls by two common methods. Timber in the form of rough sawn or planedboards or planks can be used as the loadbearing deck to a flat roof fig. 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.

3 05 timber frame pitched roof. A roof is defined in bs 6229 as a flat roof if it has a pitch of 10 degrees or less. 24 mm 20 and should have. 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. 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. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure.

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. Normally a slope of inch per foot is used. Boardsmust have a nominal thickness of min. A flat roof must be strong durable and stable throughout its lifetime.

The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading.