Don t try to use the tile setting adhesive or drywall joint compound to patch plaster walls.
Tiling on heavy gypsum plaster wall.
Firstly check the condition of the plaster skim it should be fully dried out and a light pink colour.
If you have a tiling job to do in your bathroom and the walls have been skimmed with plaster you have to follow a few guidelines when installing tile to make sure you do not have a failure resulting in all the tiles coming off the wall.
Recommended thickness of the board is at least 12 5 mm.
Tiling onto plasterboard walls.
Tiling onto plaster backgrounds plaster is a weak material compared to brick and cement.
Holes or cracked plaster requires patching.
The adhesive and tile will block moisture from evaporating.
It should be a minimum 12 5mm thick when fixed to timber framing or battening and fixed in accordance with the manufacturers recommendations.
The primary hardening of the tile adhesive takes 1 2 days and the full up to 7 days.
Expected load for tiling onto gypsum board should not exceed 32 kg m2.
Laying of tiles on gypsum plaster is carried out in 7 14 days.
However tiling over tile can add quite a bit of thickness so make sure your wall can handle the weight.
Fresh plaster needs up to a month for the material to set in and fasten.
When applying tile to a plastered surface it is important not to overload the weight of what the plaster will take before failure occurs plaster will support about 20kg m2 or about a 9mm thickness of ceramic tile.
Tiling over damp plaster causes the wall to fail because the plaster won t become strong if it can t dry out.
It is needed for the adhesive to bond well.
It is believed that the cement sand mortar dries at a speed of 1 cm in 7 days.
Preparation for tiling onto plasterboard plasterboard should be dry securely fixed and rigid with no protruding fixings with the face to receive decorative finishes exposed.
You should not tile over wallpaper glossy surfaces lead paint or plywood.
Make sure that gypsum board plaster board is strong enough to support the load from tiles and adhesive.
Fresh plaster whether applied as a patch or to the entire wall must dry completely before tile is applied.
The drying time is also affected by the thickness of the plaster layer.
What this means for your installation is once it has been determined the gypsum board and its supporting structure have been properly designed constructed and installed to support a tile installation consult your setting material manufacturer to determine which of their adhesives or mortars and possibly primers are recommended to bond the tile to the painted gypsum substrate.
If you re not sure if you have lead paint test kits are available.