Preparing for tiling - "priming"

Discussion in 'Tilers' Talk' started by Dr Bodgit, Jul 12, 2018.

  1. Dr Bodgit

    Dr Bodgit Well-Known Member

    Hey guys and gals, after a bit of info from those in the know.

    Had the tiler round a while back to quote, I've not followed up with him as still getting everything ready and am nearly there, will then email him to get the quote!

    He said there was no need to "tank" the walls or whatever, but would fill the bath, seal it around the edges then "prime" the walls and I'm wondering what this normally entails. Walls are mainly newly plastered (not polished smooth) and 18mm ply which will have 6mm backer board on top.

    Please educate me in the ways of preparing for tiling :)
  2. rogerk101

    rogerk101 Well-Known Member

    I would not prime the walls with anything. Any good flexible tile adhesive will adhere perfectly well to new plaster, so no priming necessary.
    If it's a bath that will also be used as a shower, I would definitely tank the walls before tiling. I would position the bath, fill it with water, and then seal the bath-wall junction with a good silicone. I would then put a line of masking tape on the rim of the bath, just slightly less away from the wall than the thickness of the tiles, and I would tank the wall right down covering the silicone and right up to the masking tape. Apply at least two coats of tanking slurry. (I always just carry on adding coats until I've used it all up, as it doesn't keep anyway.) Coats should be applied at 90 degrees to each other to ensure complete coverage. Only then should you start tiling.
    If it's just going to be used as a bath, and there is somewhere else to shower, I wouldn't bother tanking it.
  3. Dr Bodgit

    Dr Bodgit Well-Known Member

    The bath will have a shower over it, the tiler said no need for tanking which I think is a contentious topic...previous place had tiles on plasterboard with no tanking and I never had any problems, I guess its an issue if water gets behind and how porous the grout is?

    I'll chat with him more about sealing/priming/tanking so I understand the options and implications.
  4. rogerk101

    rogerk101 Well-Known Member

    For the cost of a tanking kit big enough to do a shower area above a bath, I wouldn't even think of not using it. £40 for a tanking kit will seem extremely cheap if you ever have to redo it.

    I would even go the extra mile and use a good quality grout sealer once the grout has dried out completely ... good old belt and braces stuff.
    Dr Bodgit likes this.
  5. LEH

    LEH Member

    Tiling directly onto gypsum plaster with cement based tile adhesive risks tiles debonding, priming prevents this. However, as said above, you definitely need to tank, which will anyway solve both problems and provide a suitable surface to tile onto. Also make sure you are not going to be over the load limit of 20 kg/m2 for skim...
  6. Dr Bodgit

    Dr Bodgit Well-Known Member

    Thanks...load limit should be fine, tiles are not heavy.
  7. CGN

    CGN Well-Known Member

    I always prime...only takes a few mins.

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