Suspended timber floor
Contents |
[edit] Introduction
Suspended timber floors are sometimes referred to as hollow timber floors. Suspended timber floors are not the same as floating floors or raised floors.
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.
[edit] History
This type of construction was commonly used during the Victorian era. It is still found in older buildings and is sometimes used to create a level ground floor when ground surfaces are uneven.
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.
For more information on load bearing sleeper walls, see Sleeper wall
[edit] Key points
To prevent moisture from accumulating in the gap between the floor and the surface below, ventilation is essential. This can be accomplished by fitting airbricks in 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.
For more information on dealing with damp proofing, see Damp proofing buildings
[edit] Issues of suspended timber floors
In addition to damp, there are two common issues associated with suspended timber floors: drafts and noise.
[edit] Drafts
Gaps associated with timber or hollow floors increase the tendency for drafts to occur. These can be tackled by methods including:
- 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.
[edit] Noise
It is not uncommon for suspended timber floors to creak over time, especially when joists move and nails loosen. Resolving this issue can be complicated and may involve reinforcement or replacement.
See: Sistering floor joists.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Heritage staff wellbeing at work survey.
A five minute introduction.
50th Golden anniversary ECA Edmundson apprentice award
Showcasing the very best electrotechnical and engineering services for half a century.
Welsh government consults on HRBs and reg changes
Seeking feedback on a new regulatory regime and a broad range of issues.
CIOB Client Guide (2nd edition) March 2025
Free download covering statutory dutyholder roles under the Building Safety Act and much more.
Minister quizzed, as responsibility transfers to MHCLG and BSR publishes new building control guidance.
UK environmental regulations reform 2025
Amid wider new approaches to ensure regulators and regulation support growth.
BSRIA Statutory Compliance Inspection Checklist
BG80/2025 now significantly updated to include requirements related to important changes in legislation.