Marine Ply vs Structural for Bathroom Subfloor

Discussion in 'Builders' Talk' started by jbdiy, Nov 12, 2019.

  1. jbdiy

    jbdiy New Member

    Hi all,

    Question no doubt asked 100's of times, but wanted to check a few things.

    I'm renovating bathroom and taking up floor - the old chipboard is very bad in several places.
    The floor will be finished with Karndean (splashing out as it's not a big space at all) and they insist on SP101 to be laid before their adhesive.

    The fitter however have said there's no point in laying the Karndean under the bath, waste of money he said, this would mean the area under the bath would be exposed - but still covered by the bath, bath panels etc which would be siliconed etc. No direct water, but still - it's a bathroom, so... moisture etc. + cut out for bath waste.

    My questions is: I'm going to need to put a subfloor down (joists are good and plenty of noggins) and am wondering if Marine Ply or Structural ply would be suitable for the subfloor - bearing in mind it will be exposed under the bath, what would be best? Looking at 18mm minimum.

    Also, if it needs sealing - what should I use? I've some SRB spare...

    Thanks all for your time.
  2. Jord86

    Jord86 Screwfix Select

    A decent WBP ply will do, marine ply costs a fortune, it’s all to be covered anyway, 18mm thickness for 400 centres joists, 22mm for 600mm centres. SBR is fine.
    TheMorg likes this.
  3. soabar

    soabar Member

    Have a similar set-up with WBP & SBR lasted years so far withoout any issue.
  4. Astramax

    Astramax Super Member

    Marine ply would be totally over the top, go for WBP as others have already suggested. ;)
  5. rogerk101

    rogerk101 Screwfix Select

    I have used 22mm T&G chipboard flooring in all the bathrooms I've worked on, and never had a problem yet. Get the slightly more expensive chipboard intended for wet environments. I pay about £12 for a 1200mm x 600mm 22mm board.
    Astramax likes this.

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