This technical update provides additional guidance on ceramic floor tiling on timber floor constructions, domestic. It is important that all workmanship carried out during construction is completed in accordance with the relevant tolerances.
Where ceramic tile floor finishes are proposed as part of the ’completed’ internal floor finishes, it is a fact that under normal loading, timber floor joists will deflect more than the allowable tolerances that a ‘ceramic covering’ can accept and cracking in the tiles, particularly at floor board junctions, will occur.
The following solutions are acceptable to meet our warranty Technical Manual requirements:
The guidance below is for ceramic tiling only and does not apply to other heavier tiles such as marble, travertine or stone which would be considered too heavy for a traditional suspended timber floor construction.
The floor must be fit for purpose and should have adequate stiffness to support the tiles and adhesive.
For floors supported by joists up to 600mm maximum centres, the floor decking should be:
Existing timber floors to be covered by ceramic tiles should be sufficiently strong and rigid, therefore:
For walk-in showers and wet rooms, timber floor deck substrate is not acceptable.
De-coupling layers provide an intermediate substrate between the tile covering and load bearing substrate including timber floors and decking materials. They are designed to neutralize lateral stresses that occur between the substrate and tile covering; they are not designed to accommodate differential vertical movement. De-coupling layers are considered to offer a robust approach to preventing ceramic tile failures, where ceramic tiles are laid on a flexible timber substrate. However, it does not preclude the requirement to provide strengthened/stiffened joists and overlay decking (as described above).
Note: For the purpose of this article, we are looking only at providing advice on ceramic tiling proposed on timber floor decks with a timber joisted (solid and I joists) support. Marble, travertine or stone type coverings on either timber, concrete or screeded floor substrates are not discussed.
Every care was taken to ensure the information in this article was correct at the time of publication. Guidance provided does not replace the reader’s professional judgement and any construction project should comply with the relevant Building Regulations or applicable technical standards. For the most up to date Premier Guarantee technical guidance please refer to your Risk Management Surveyor and the latest version of the Premier Guarantee Technical Manual.