Floor Tiles onto Bitumen DPM

Discussion in 'Tilers' Talk' started by SDN8BD, May 20, 2020.

  1. SDN8BD

    SDN8BD New Member


    I will shortly be tiling the hall and kitchen floor in our 1950s semi with 450x450 ceramic tiles. I am unsure what preparation/priming I should do to the existing floor in advance however and what adhesive would be recommended?

    The floor is the original concrete slab with approx 10-20mm thick layer of bitumen laid over the top (as far as I know this is the original Damp Proofing Layer). The surface of the bitumen is mostly a mid-brown colour which is possibly a painted layer (cloth turns brown if scrubbed on the floor) but the surface is not dusty and is fairly smooth.

    The bitumen in the hallway is nice and flat with no damage so tiling should be relatively easy.

    In the kitchen there are a couple of areas where there are patches of cement where the original hearth was and where a wall has been removed. These all have had a liquid DPM applied before the cement infill to bring the levels back to the top of the bitumen. There are a few small local dimples and an area by the back door where there is a raised lump. I was planning on removing the area where the lump is and using the same liquid dpm and cement filler.

    I have read totally mixed views on tiling onto this type of surface. I was planning on a flexible adhesive though from what i have read. Can anyone make any recommendations at all please?

    I dont really want to have to dig all of the bitumen out and re-screed as the existing floor is in good condition and the adjoining lounge floor has a finished (bamboo) floor already laid.

    Thanks in advance,
  2. DIYDave.

    DIYDave. Screwfix Select

    Most important thing here is to prime the bitumen and concrete repairs to get a good bond between tile adhesive and floors

    Tile brands such as Bal, Ardex, Tops, etc all sell tile primers with fancy names !

    Can simply use SBR diluted, follow instructions on bottle, likely to be 1-4 water, then apply 2 coats

    ‘Small dimples’ will be filled by the tile adhesive and as you’ve said, your removing the raised lump

    Use powdered ‘bagged’ tile adhesive and grout, much better quality than ready mixed buckets. Speak to your tile supplier and see what they recommend. Also check it’s suitable for tile type - if porcelain, not all adhesives are suitable for this material

    You sure the bitumen is up to 20mm thick ? Sounds a lot ?

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