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For wall tiling applications it is essential that the wall itself has sufficient inherent strength to hold the proposed tile and the adhesive being used.
The following chart lists the accepted maximum loadings for a variety of wall substrates. In all cases, it is advised that where wall boards, of any type, are used that the manufacturer be consulted for further guidance.
Wall Substrate Maximum tile weight
(plus adhesive and grout*)
Gypsum plaster 20kg/m²
Plasterboard (gypsum) unskimmed 32kg/m²
Plywood (exterior grade) 30kg/m²
Gypsum fibre boards 40kg/m²
Tile backer boards 40kg/m²
Glass reinforced cement sheets 50kg/m²
*Typically the weight of the adhesive and grout is 2-4kg per m².
Wall types vary considerably but all have the same basic need to be structurally sound, strong, smooth and level.
It is important to understand that tile adhesives are not designed to be a method of overcoming surface undulations and unevenness.
The specifications for various substrates and their stability are listed below. Should any other substrates be encountered, please contact the UltraTile Technical Department.
A – Block work wall construction
B – Existing tiles
C – Prime using UltraTile ProPrimer neat
D – Apply adhesive (flexible only should be used)
E – Install tiles
F – Grout all joints
Ideally, existing tiles should be removed and then the substrate can be prepared as required. However, it is accepted that on occasions removal of existing tiles may not be an appropriate method so a ’tile on tile’ installation is necessary. The existing tiles must be securely bonded to a sound stable background that is capable of accepting the weight of the original tiling plus the new tiles. Tiles that sound hollow or loose should be removed and the exposed area primed prior to applying a cementitious repair mortar. Existing tiles should be degreased and then lightly abraded to provide a clean mechanical key.
Priming:Class as non-porous and refer to chart on pages 10 & 11 of the UltraTile Brochure.