Timber Flat Roof Construction Details

150mm insulation 0 044w mk between rafters.

Timber flat roof construction details.

Flat roofs on houses must be designed and built to be strong durable and wind resistant. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. Load bearing or primary structure usually constructed in timber in a residential construction. A roof is defined in bs 6229 as a flat roof if it has a pitch of 10 degrees or less.

A flat roof must be strong durable and stable throughout its lifetime. 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. The abutment detail of a flat roof is vital in order to prevent moisture penetration.

For additional stability you can also use steel joists that are built into one or both of the walls. In this type of construction the insulation is placed below the waterproof covering and on top of the roof deck and vapour barrier. The flat roof shown above shows warm deck roof construction. 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.

The size of your joists and noggins and preliminary timber layer will be determined by the weight of your flat roof. Solid external masonry wall. Having a manual for warm flat roof construction with details and a summary of rules to follow helps. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off.

The construction of the flat roof is similar to that of the timber upper floor. 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. This ensures that the deck holds a warm temperature during the winter.

It must provide adequate protection against the elements keeping the buildings structure and interior dry.