Timber Flat Roof Construction Details

In this type of construction the insulation is placed below the waterproof covering and on top of the roof deck and vapour barrier.

Timber flat roof construction details.

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. It must provide adequate protection against the elements keeping the buildings structure and interior dry. Solid external masonry wall.

The construction of the flat roof is similar to that of the timber upper floor. Load bearing or primary structure usually constructed in timber in a residential construction. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. Flat roofs on houses must be designed and built to be strong durable and wind resistant.

The abutment detail of a flat roof is vital in order to prevent moisture penetration. 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. 3 05 timber frame pitched roof. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off.

Having a manual for warm flat roof construction with details and a summary of rules to follow helps. For additional stability you can also use steel joists that are built into one or both of the walls. 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. 150mm insulation 0 044w mk between rafters.

215mm aircrete solid wall λ 0 15 w mk render insulation λ 0 022 w mk pitched roof gable. The size of your joists and noggins and preliminary timber layer will be determined by the weight of your flat roof. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. 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.

The flat roof shown above shows warm deck roof construction.