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Prepping chipboard floor before Hardiebacking

Discussion in 'Tiling' started by jso, 25 Nov 2018.

  1. jso

    jso

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    Chipboard flooring. Old stuff, not green.
    Have bought Hardiebacker, and slow set grey adhesive (for quarry tiles).
    1) Assume I can use the same adhesive for the Hardiebacker?
    2) What's the best sealant for the chipboard prior to installing the Hardiebacker? (Have gathered from reading on here that it shouldn't be something that will skin.)

    Adhesive is ToppsTiles own - local branch, so convenient delivery etc. Have emailed about chipboard sealant, but not heard back yet. In any case,more than one opinion would be helpful.
     
  2. Yeahaa

    Yeahaa

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    Screw the boards to the chipboard using self tapers , dont need to seal the chipboard the cement boards protect it , could use a pva sealer on the chipboard , can seal the joints with silicone .
    Is not like will be rivers running under the tiles .
     
  3. bobasd

    bobasd

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    is it square edge or T&G chipboard?
    typicly, you use powdered adhesive combed onto the floor an then lay and screw the backer board down.
    is the finish goin to be Quarry tiles?
    how much moisture will the finished floor be exposed to?
     
  4. jso

    jso

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    Ah. OK. Thank you!
    I'd thought the chi[pboard neede to be sealed to assist the adhesive in some way. So the idea of sealing the chipboard is to make it more waterproof in case of water ingress?
    This is a conservatory/garden room floor, so the most it should get wet will be possible spillages when watering plants, and washing the floor from time to time.
     
    Last edited: 27 Nov 2018
  5. jso

    jso

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    Thanks for the response. It seems to be T&G. As I found when removing the carpeting it's nailed onto the joists, but the joints between boards seem very secure, so it must be T&G.

    Ultimate finish will be quarries. Conservatory/garden room, so occasional spillages from overwatering, and the usual washing of the floor...

    Subsidiary question: should I screw the chipboard to the joists in addition to the original nails?
     
    Last edited: 27 Nov 2018
  6. jso

    jso

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    ToppsTiles have suggested a BAL sealant that soaks into the chipboard - but maybe, according to Yeahaa, I don't need to bother with this?

    They have suggested rapidset adhesive for the Hardiebacker. I'm about to collect some from them. Does this seem right?

    Also they originally sold me Hardiebacker screws. Will these be OK for chipboard, or should I swap them for chipboard screws eg from screwfix? (and selftapping at that?)
     
  7. Yeahaa

    Yeahaa

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    The screws go every 200mm or less , basically peppered so is no glue required screw them down tight .
    The cement board supplier will stock the special screws
    Sealing the chipboard is pointless tbh keeping it practical.
    So long as in good condition and not loose or creaky the cement board can go straight over the chipboard .

    Careful if your driving big screws of pipes underneath to secure loose chipboards dont want to end up with a river
     
  8. jso

    jso

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    OK. Thanks. TBH the idea of using adhesive as well as screws came from discussions I've read (possibly on here?) where e.g. pros have criticised amateurs for just screwing the backerboard, and not using adhesive. Apparently the adhesive is supposed to make up for minor imperfections or voids etc. I can see that this could be advisable on floorboards, whereas my floor is a seemingly flat chipboard floor....Don't get me wrong - I'm certainly not wanting to make extra work for myself, but equally don't want to take short cuts which lead to cracked tiles! I'm doing 25 sq.metres - about 1000 tiles...so it could be a big mistake if I do it wrong!
     
  9. Yeahaa

    Yeahaa

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    I think your method involves sticking down the hardie with 2 beads of adhesive using 12 minimal screws to tack it down while the beads of adhesive set .

    My method is fixing the board mechanically using screws at measured centres to ensure all the board is fixed solid

    Would not want to introduce any moisture to the chipboards before covering them myself
     
  10. jso

    jso

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    Aargh! It's all so confusing. I've seen beads of adhesive suggested for no-more-ply, but Hardiebacker recommends combe d out all-over adhesive. In which case the sealant would be, presumably, to protect the chipboard from moisture from the adhesive! They've also said that the adhesive is to even out the bed for the backerboard: the mechanical fixing is still what keeps it in place.

    Well, I've got some walls to paint before I start on the flooring, so I'll keep thinking about all of this. Thanks for the input!
     
  11. bobasd

    bobasd

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    above i've mentioned how its done.
    screwin down the c/board you risk hittin cables or pipes but its always best practice to lay sheets with screws.
    use , say 18mm screws to fix the backerboard - you want to avoid penetratin the c/board an the backer board. avoid screwin down into the the joists - it will allow a little movement with the backer board an prevent tile cracking .
     
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  12. jso

    jso

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    Thanks. The chipboards are nailed to the joists. Do I need to screw them down as well, before fitting the Hardiebacker?
     
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