Tiling on New Plaster: How long to leave plaster before tiling?
Tiling onto plaster is relatively straightforward. When you place tiles directly onto plasterboard, this often means you don’t have to prepare or prime the plasterboard prior to doing it.
So long as you’re well prepared, tiling needn’t be difficult. Make sure you plan and measure carefully to prevent any mistakes. If the backing is strong enough to support the weight of tiles, tiling can be performed on numerous clean, even and dry surfaces.
If in doubt, as a professional but so long as you’re savvy when considering the weight of the tiles and the location of the tiling, you shouldn’t encounter any issues tiling straight onto plaster.
Planning is Key
The key to success? Preparation. If your wall has been plastered recently, make sure it has been left for at least 14 days before tiling on new plaster. If the plaster is old, ensure there aren’t any loose materials, cracks and hollows by tapping the plaster and listening out for any hollows.
Tiling a wet room? Make sure you install a layer of cement board, so the area is completely waterproof and secure. If this isn’t necessary, a coating of sealing primer directly on the plaster will ensure a decent base, just make sure you give it 24 hours to dry. If you’re tiling a pattern, organised the layout prior to starting so no time is lost, and no mistakes are made.
It is important to plan when tiling onto plaster backgrounds to avoid small and problematic cuts which cause the tiling to look shoddy and slapdash as well as making it incredibly tricky to cut.
Tiling Onto Plaster Backgrounds
Plaster is a weak material compared to brick and cement. 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.
New plaster work should be fully dried before tiling work is commenced, this drying time varies upon temperatures but can take up to 4 weeks before fully cured.
Plaster is not ideally the best surface especially in a bathroom as moisture and water can get in causing failure.
When using a cement adhesive on your tiling projects you have to be careful when tiling direct onto neat plaster. Gypsum plaster based products and cement products do not get on with each other and can cause de-bonding, this is due to the chemical reaction that goes on when the two come together. This reaction forms a weak layer of ettringite, which can cause the failure.
To stop the ettringite reaction, plaster surfaces must be primed with a diluted acrylic primer or SBR, this primer acts like a barrier and stops the 2 products from contacting each other. PVA must not be used
Another problem when tiling on plaster is to be careful that the plaster has not been over troweled which results in a smooth shiny finish, this finish will have to be roughed up a bit with a wire brush prior to priming.
Good quality tiling courses can give you a good understanding of how to tile and understand the backgrounds. UK Pro Tiling Training offer fast track courses teaching you all you need to know about tiling, for more information visit www.tiling-courses.co.uk