Waterproof chip flooring, why so bad?

Discussion in 'Tilers' Talk' started by Tauruss, Jan 22, 2007.

  1. Tauruss

    Tauruss New Member


    Just read a topic involving chipboard used in a wall, the recurring subject of PVA and some negative comments on the use of waterproof chipboard.
    My question is about the relative merits of chip vs. ply as reinforcement to a wood floor before tiling.
    I have seen the effects of water exposure to non waterproof chip flooring (not tiled), mush!
    Properly fixed down, tiled and grouted it should be fine, right?


  2. ­

    ­ New Member

    No such thing as waterproof chipboard. You may be thinking of moisture resistant. This is better than the standard stuff but still swells up if left wet for too long.

    If you're going to overlay an old floor, why use chipboard when ply is the right product? The difference in cost is minimal and the work involved is the same.
  3. audi-evo

    audi-evo Active Member

    Why is chipboard flooring bad, coz it creaks like f* after a very short time also is prone to sagging on joists.
    And yep water resistant aint water proof, when it swells at the joints they turn up and give you problems with any floor covering you decide to use.
  4. Somewhere on here is an excellent post detailing why you should not prime with PVA before tiling, but I can't find it.

    Basically when you apply the tiling adhesive over the PVA the water content of the tiling adhesive softens the PVA and you end up bonding to a damp film of PVA rather than the surface of the substrate.

    With regard to chip v ply;

    Plywood because of its structure is far more rigid than chip and so is less likely to deform when load is applied.

    Also the surface soundness of chip is significantly lower then plywood. Surface soundness is a measure of the resistance of the surface of a material to hold onto something that is bonded to it. (sorry terrible explanation but its late) The lower the surface soundness the worse the performance and while it is some years since I did any testing, I remember that plywood is on the order of 3 to 4 times stronger than chipboard
  5. ramsden

    ramsden New Member

    Chip is awful. My house is less than 20 years old and I've already got sagging creaky floors. My parents old house was 200 years old and although I don't know if their floor boards were original they're certainly old and in fine nick!

    The only reason they use chip in modern developments is 'cos it's cheap. It's impossible to make it waterproof because of it's very structure - tiny mushed up bits of wood compressed. Over time this will produce lots of miniscual gaps for moisture to penetrate. In my experience I'd suggest getting external ply laid down before you do anything. I found out the hard way! I've now gotta rip up my floor around a newly installed/decorated kitchen!

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