Wooden planks bathroom leak tiling

Discussion in 'Tilers' Talk' started by Conor333, Jan 14, 2021.

  1. Conor333

    Conor333 New Member


    Had a leak in the bathroom. Pulled up old tiles and old laminate type subfloor. Left with wooden planks on the joists. Some of them were quite wet and had a black layer on them.

    We've dried them out now - are they suitable for reuse if dry? Do they need treated?

    Also, if we use a backboard on top what is a suitable adhesive to bond the board to the planks?


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  2. AnotherTopJob

    AnotherTopJob Screwfix Select

    If the boards seem solid with no sign of rot, then a good clean with bleach or a mould killer would be the minimum preparation.
    It is quite likely there is also mould or rot underneath which ideally needs addressing. It might be worth removing a board and assessing the condition of the joists etc.
    It's a good idea to seal the wood with an acrylic primer before laying the backer board onto a solid bed of cement-based flexible fast setting adhesive. This will fill any irregularities and give a good solid base.
    Conor333 likes this.
  3. DIYDave.

    DIYDave. Screwfix Select

    The ‘wooden planks’ on the joists are more commonly known as floorboards

    They can take a fair amount of water over a period of time before they actually rot / just depends how long the leak was going for

    Simply test the soundness of the boards by jabbing them with say a screwdriver in several places. If the boards are rotten, screwdriver will easily dig into board, maybe a few mm, if totally gone, screwdriver will pass through board without too much force

    Just be aware - highly likely to be pipes and maybe cables under boards

    If boards are soft, screwdriver digs in easily, then yes, best to replace, maybe not all of them, may just be sections

    If boards seem ok, give them a scrape over to remove black mouldy stuff, sweep, then wash over with hot soapy water with bleach added

    Will clean the boards a bit, kill the mould and make them smell better as may smell damp ?

    Check all boards are securely fixed down to joists

    With the backer board, you talking about cement board here ? Are you planning on tiling the floor ?
  4. Conor333

    Conor333 New Member

    We've had a dehumidifier today and most of the boards are hard doing what you're suggesting above with a screwdriver. One small section we'll cut out and replace.

    Yeah we're planning on using a cement board like Hardie's and tile on top. Can the adhesive be applied directly onto the floorboards?
  5. Jiml86

    Jiml86 Active Member

    Like Dave says depending on how long they were wet they may be ok. Had you lots of cracked tile? If you are going for tile again it may be worth your while getting floor boards up, replace with ply then a waterproof membrane on top of that.boards generally have flex in them so crack your grout/tile
  6. Conor333

    Conor333 New Member

    Cheers. We didn't have any cracks in the tiles just the bad leak. Would a cement board help with any potential flex from the boards?
  7. Jiml86

    Jiml86 Active Member

    Yeah anything to firm it up but if it wasn’t an issue your boards must be pretty sound anyway.
  8. AnotherTopJob

    AnotherTopJob Screwfix Select

    As long as you prime the wood, it's fine to apply adhesive onto it.
    However much you reinforce it, you'll always get slight movement on a wooden floor. If it's pretty solid, you shouldn't get anything more serious than hairline cracks in the grout.
    A thick backer board or plywood will help but it's really designed to level the surface and provide a good substrate rather than add strength.
    Also be aware that it could make the floor level unacceptably high.
  9. DIYDave.

    DIYDave. Screwfix Select

    Sounds good news that the boards are mainly sound - result !

    After cleaning and allowing boards to dry, I would;

    Check all securely screwed down

    Remember pipes will be underneath so if adding more screws, treat with caution

    Prime boards with SBR diluted 1-4 with water
    Wickes sell a 1ltr SBR, most other places 5lt
    1lt diluted will be plenty

    As ATJ mentions above, lay cement boards onto a screed of tile adhesive using a notched trowel. Also screw boards down, using a screw length that doesn’t go through bottom of board (remember pipes :eek:) !

    Idea is to give a rock solid base for the tiles

    Just give the cement boards a wipe over to remove dust and tile away

    Hardie website talks about special screws and taping the joints but ........

    Hope all goes well
  10. RolandK

    RolandK Screwfix Select

    Just a suggestion to add to the good advice above based on experience. I would definately fix the boards down with the special washers available and stainless steel screws. Extra insurance for minimal cost and effort.
  11. Conor333

    Conor333 New Member

    Thanks cheers! Would a matt like Ditra wok instead of hardie? Or better going with the backer board?

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