Following a review of British Standards for wall and floor tiling, plywood and other wood-based sheets have been excluded as a background material for the direct fixing of ceramic wall and natural stone tiles on walls.
A significant uplift in the use of tile backer boards and a wide variation in quality of plywood available on the market has provided a solid case for the removal of plywood and wood-based sheets from BS 5385 Part 1: 2018 Wall and Floor Tiling.
David Wilson, Head of UK Technical Services at Dunlop – manufacturers of tiling, decorating and flooring products for the trade – and a member of the Tile Association Technical Committee which makes standards recommendations said: “Previously it was recognised in BS5385 Part 1: 2009 that tiling direct to plywood was possible, providing this was restricted to small areas and be “installed in such a way that they provide a dimensionally stable and rigid background” the quality of plywood for tiling purposes has decreased significantly with cheaper imports flooding the market.
“While higher quality external grade plywood is still available – it is significantly more expensive.
“It is important to consider though that that wood is a hygroscopic material which means that its moisture content will change dependent upon any changes in the environmental conditions on site. Therefore, dimensionally stability of wood-based boards cannot be assured and there is always a risk to installing ceramic or natural stone tiles onto plywood or other wood-based sheets.
“Another technical consideration for wall tiling is weight restrictions. Plywood is deemed to have a maximum weight of tiling per m² of 30 kg compared to proprietary tile backing boards which generally are capable of supporting heavier weights per m² of tiling.
“A competitive tile backing board market means that prices are more attractive to tile fixers and contractors. This combined with the additional features and benefits of providing background for tiling which are dimensionally stable and resistant to moisture and thermal movement.”
However, while plywood is now not recommended as a background for direct wall tiling, it can still be used as a structural board when overlaid with a suitable tile backing board, particularly where installation of mechanical fixings is required e.g. for mesh backed natural stone where it is not possible to remove 75% or of the mesh backing.
For full technical advice please contact Dunlop Technical Helpline on 01782 591120.