Timber Flat Roof Construction Details

A flat roof must be strong durable and stable throughout its lifetime.

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. For additional stability you can also use steel joists that are built into one or both of the walls. Applying a liquid waterproofing agent will often add a few more years to the roof. 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.

A popular method involves a cold application bitumen emulsion which is applied onto the surface. 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. 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. It must provide adequate protection against the elements keeping the buildings structure and interior dry. Having a manual for warm flat roof construction with details and a summary of rules to follow helps. Others would treat even steeper pitches as flat roofs.

A roof is defined in bs 6229 as a flat roof if it has a pitch of 10 degrees or less.