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Last edited 17 May 2021
Suspended timber floor
This is a method of floor construction in which timber joists are supported by load bearing walls or foundations and typically covered with floorboards on the top. This creates a gap to accommodate ventilation and reduce the chance of damp accumulation.
In the 1920s, improved construction methods resulted in refinements to suspended timber floors. Floor joists were regularly supported on honeycombed sleeper walls and joists were not in contact with external walls.
Additional guidance for suitable procedures for suspended timber floors can be found in Building regulations Part C: Site preparation and resistance to contaminants and moisture. This document covers the weather-tightness and water-tightness of buildings, subsoil drainage, site preparation and additional issues relating to damp proofing and ventilation.
 Issues of suspended timber floors
- Draft excluders. These include synthetic fillers and draft proofing adhesive strips.
- Insulation. Building regulations now require insulation in timber floors. For more information, see Floor insulation
- Tongue and groove floorboards. This technique produces a strong bond that is suitable for floating floors. For more information, see Tongue and groove joint
- Underlay and carpet.
- installation of a subfloor on the underside of the joists.
See: Sistering floor joists.
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