Roof Deck
/roof dek/
Also known as: decking, flat roof deck, structural deck, OSB deck, plywood deck, metal deck
Definition
The structural base layer of a flat or low-pitch roof onto which the insulation and waterproofing membrane are laid. Common materials include OSB/3, structural plywood, concrete, or profiled metal decking. The deck must be rigid, stable, and provide adequate support for the roofing build-up.
In Practice
For warm flat roofs on timber-framed buildings, 18mm or 22mm OSB/3 or structural plywood is the most common deck material, fixed to timber joists or rafters. The deck must be clean, dry, and free from voids before the vapour control layer and insulation are laid. On commercial buildings, profiled steel decking is common. The deck moisture content should be below 20% at time of installation.
UK Building Regulations
BS 6229 - Flat Roofs with Continuously Supported Flexible Waterproof Coverings
BS 6229 covers the design and construction of flat roofs. The deck must be dry at time of installation - wet decking causes blistering and delamination of the waterproof membrane above.
See Also