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NZ Tilers Forum Expansion Joints, Control Joints And Anti Fracture Membranes.

Discussion in 'NZ Tilers Forum' started by Bob Neary, Jun 12, 2013.

  1. Bob Neary

    Bob Neary Tiling Forum Moderator Staff Member

    Hi guys, I was discussing a job with one of our local tilers to start this week. The job is typical of requiring a solution that will isolate the finished floor from movement between two substrates on the same level. That is concrete and timber sheet flooring.
    I know we've discussed aspects of such jobs but I really want to clear this up once and for all.
    No matter where you live I'd appreciate any input.
    To start with I don't think telling the client there is no solution and not to lay tiles, is a solution,There WILL be a tiled floor. The question is will it still be in good nick in years to come.
     
  2. jay

    jay Awesome Contributor

    A change in substrates requires an expansion joint
    But if the floor allows plastic expanding metal and screed over might be the answer depending on the position of the change in substrate

    OH im from TAZ Bobby
     
    garythetiler likes this.
  3. Alan jackson

    Alan jackson Tiling Products Support

    Expansion joint is perhaps the wrong and slightly misleading term as the floor will not expand appreciably unless heated significantly. The term movement joint is probably more correct as the two substrates will move at different rates to different levels. either way Jay is correct that a joint is required between the two substrates.

    Expamet is a possibility I guess but for it to be effective it would need secupurely fixing mechanically to both sides and would need to extend a good way onto each side to work.
     
  4. Alan jackson

    Alan jackson Tiling Products Support

    I've also often wondered if an epoxy stitch could be effected between substrates of differing materials. Might be worth looking into.... Stick the two substrates together permanently
     
  5. widler

    widler Serious Contributor

    Ive tiled loads, ive just spanned them with either ply(years ago) of backer boards.
    I really don't understand all the caffuful about this, ive rendered over 2 different substrates many times,old house with timber framed extension,no problems.
    I alpined a wood framed house about 5 years ago,ply, EML , rendered and then alpined, i pass it most weeks, no problem with it what so ever, and the weather we have been having these last few years i would of thought these external jobs get more movement than a internal floor with a few tiles on ,and more stress with weight !
    As long as its preped right , whats the problem ?
     
    garythetiler and Bob Neary like this.
  6. Bob Neary

    Bob Neary Tiling Forum Moderator Staff Member

    The tiler I was discussing this with came to the same conclusion. My only concern really would be how the substrate sheeting (be it ply or fibrous cement) was fixed. And how it would behave according to how it was fixed to the floor.
    The conclusion in this case was to glue and nail to the timber and glue to the concrete. I've done this but only because the concrete section was a triangular part of the main floor which was timber. I didn't want to put a control joint on the 45 as it would be ugly. Never had a call back.
     
    widler likes this.
  7. jay

    jay Awesome Contributor

    It is mainly the way the two subs move in different ways .Timber moves both ways were as concrete doesn't (to extremes)
    as for tiles they don't like any movement
    What is really needed is a layer of something that can handle the movement without transferring it through to the tile .
     
  8. Grace's Dad

    Grace's Dad Tiling Forum Moderator Staff Member

    Water!
     
  9. Bob Neary

    Bob Neary Tiling Forum Moderator Staff Member

    You're being rather diplomatic about this Jay.
    If there was no other option but to straddle the joint, what would you use to bridge it safely? Or are we expecting to much here?
     
  10. Alan jackson

    Alan jackson Tiling Products Support

    You can't straddle it "safely" as there will always be risk at that point. You only hope to mitigate the risk. You could always stick the tiles over the joint with silicone...
     
    branty1uk likes this.
  11. widler

    widler Serious Contributor

    I think we are all pissing in the wind debating stuff like this, every substrate ever invented in over 2000 years has been tiled on at some point.
    Yet folk invent stuff to stop deflection ect ect which costs extra then tell tradesmen/customers to fit it because you will have problems with it even though you have done it umpteenth times over the years with no problem,scaremongering !
    I will put money on any tiler with over say 10/15 years have tiled on ply, or over 2 different substrates with no problems.
    Again,If its prepped right what will be the problem!?
    A concrete floor or screed will settle/move as well as wood, u really can't guarantee owt from not moving !
     
    Bob Neary and ray like this.
  12. jay

    jay Awesome Contributor

    On a small floor say toilet floor (sometimes the pan sits pan sits on a slab and the rest of the toilet floor is timber) depending on the deflection ,6mm cement sheet glued and screwed might work but on a larger floor nope,

    Yes we have adh that can stick to timber ect you could throw a S2 adh at it (the adh will have 7 mm of flex but not your tile)
    If the adh manufacture won't guarantee it or Hardies then how on earth can we
    Anyway a well executed expansion joint is not that bad
     
  13. branty1uk

    branty1uk Tiling Forum Moderator Staff Member

    The thing is, the products are inveted because there's a problem, not the other way round.
    The first ever cars didn't have seat belts.
    You could well drive for years and years with no seat belt and never need it.
    [​IMG]

    If you spent a week with a BAL Product Support Technician, you'd see these kind of failures.
     
  14. ray

    ray Superb Contributor

    you are right .but 10 years a go most of us could fix and maintain our cars with a simple tool kit but today they have to go on a computer to try to track problems and with so many senesors to check through it can cost you a small foutune if they can find whats wrong and guess what you have to go to main dealers so were the inprove ments for us or to make sure the main dealers made more money so what makes a real inprovment for who?
     
    Bob Neary and AMA Tiling like this.
  15. branty1uk

    branty1uk Tiling Forum Moderator Staff Member

    And I haven't had a car breakdown on me for years, so I guess that's the pay off.
     
  16. widler

    widler Serious Contributor

    See ,we are all pissing in the wind :)

     
  17. jay

    jay Awesome Contributor

    So Widler what would be your approach to two different subs
     
  18. ray

    ray Superb Contributor

    but could you fix it if it did
     
  19. ray

    ray Superb Contributor

    hi jay this is what we used to do in the past before decouplers .if you had a floor half sand and cement other half floor boards you would screw down floor boards then lay 8x 4 ply half way between the two then screw down every 200mm but double up each side of join the prime ply and tile this was the only way to do this then with out bringing the floor hight up to much .by screeding .but in them days this was standard practis for this kind of problem .and i swear adhesive were a lot stronger then stiking to ply ? never had one single failur and used it loads of times .well every manafator likes to save money and make money weaken the adhesive then bring out a way to make more money by making the weaker product work who nows but this method was used for years by many with great suckses so what changed i wonder
     
    jay likes this.
  20. jay

    jay Awesome Contributor

    Yes have done something similar many moons ago Ray don't think it failed not sure/
    prob with today is the grade of timber being used (mainly pine) and the way they join the two subs nothing like the old days as for adh well i think we can thank the standards for the downgrade in strength ,
    They have set the bare minimum as far as adh go
     
    ray likes this.

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