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Discuss BAL Prime APD on Cement Board - Dilute or Not? in the Tanking and Wetrooms Forum area at

  1. schismatic

    schismatic Active Member

    Gloucester, UK
    I’m about to tank Hardie Backer cement boards using the BAL WP1 waterproofing kit. I’m a bit confused with the Prime APD. Should I just paint this straight on, undiluted, or should I be diluting at all? If I do need to dilute, what proportions?

  2. Andystiletiling

    Andystiletiling Trusted Advisor Professional Tiler

    One undiluted coat will be fine before tanking..
    • Like Like x 2
  3. Waluigi

    Waluigi Top Contributor

    Screeded floors need diluting 1:1 but I remember Bal being a bit funny with their installation instructions regarding WP1. At the stage at which I stopped using their system, they wanted you to skim the Tile backer board with tile adhesive and priming/tanking once dry.

    This was ten + years ago so might be worth contacting their tech team. They’re usually very good.
  4. schismatic

    schismatic Active Member

    Gloucester, UK
    Probably best if I ring them to get a proper answer, but I suspect that dilution will be required as the boards are cement-based.
  5. impish

    impish Trusted Advisor Professional Tiler

    Preston, Lancs
    Diluted 1:1 but as hardibacker is SO absorbant, I'd suggest 2 coats.
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