Which ply to use on wooden floors?

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

  1. NL

    NL New Member

    I am about to tile a wooden floor in a small bathroom, and was going to use 9mm ply screwed to the floor boards every 200mm. However there seems to be a lot of messages on here that disagree on the thickness of ply to use, is 9mm OK or should I go for 12mm or 15mm? The area of floor being tiled is only about 1m by 1.5m and the floor boards are very solid.
  2. ramsden

    ramsden New Member

    Oh you've really started something now!! This is a question I would like a specific answer too as well. I'm in a similar situ but with a chipboard base.

    I know a v reliable builder/decorator with years experience who fits for major cafe/restaurant chains, and says 9mm should do the job as long as you fix it securely to the wooden floor. However I know by simply uttering those words, I will have agitated many other professionals (probably who are all equally as experienced) with opinions varying up to and including 25mm! I think you'll never actually get to the truth of this!!

    Obviously in an ideal situation, thicker = better, it's that simple. But 25mm ply in most small rooms just isnt practical. If you tile on top of that you'll have the best part of a 40mm step to climb/trip over every time you enter the room.

    I think there's as much to be said for how you fix it, and also the flexibility of the adhesive/grout, as for the thickness of the ply. However I'd love to hear the opinion of someone who has actually DONE this type of job, AND witnessed how well it lasted over time???
  3. jasonb

    jasonb New Member

    25mm is used as a replacement to the softwood/chipboard not for overboarding.

    A lot will depend on the specific installation ie joist spacing, softwood or chipboard (18 or22mm) type of tile- ceramic, porcelain or natural stone also size of tile so as most posters do not give full details a general spec is often given.

    Type of adhesive will also play a part, lots of DIYers will use a readymixed "tile on wooden floors" adhesive which is very flexible but actually needs at least 72hrs to set rather than the 24hrs stated on the tub. Powdered rapidset adhesives are what most tilers use but they are a little less flexible.

    I would go with a minimum of 12mm WBP ply as an overlay for ceramic/porcelain screwed at 200cts.

    I generally take up the chipboard and replace with 22mm flooring grade ply if there is any question about the suitability of the chipboard or overboard with 12mm ply if its OK and height isn't an issue.

  4. NL

    NL New Member

    Thanks for the reply I was going to use one of the ready mixed adhesives. The extra drying time is not a problems as there is another bathroom to use. I guess I'll return the 9mm ply I've got and get some 12mm to be on the safe side. The tiles I'm using are ceramic and 300mm X 300mm, the floor is 20mm soft wood, and the joist spacing is about 300mm if that makes any difference?
  5. jasonb

    jasonb New Member

    With a 300mm joist spacing and readymix you should be OK to keep the 9mm ply.

  6. bathstyle

    bathstyle Active Member

    12mm ply for me, some use 9mm with success, only an imbecile would go as low as 6mm Ply for flooring but believe me there are still some out there that work in this way.
  7. Ghost-1

    Ghost-1 Active Member

    You had to get that in B

    Wonder who thats a dig at :)

  8. bathstyle

    bathstyle Active Member

    Come here you



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