Subfloor help

Discussion in 'Subfloor Preparation' started by trossachs, Aug 18, 2023.

  1. trossachs

    trossachs New Member

    Hi all,

    Looking for some advice. I currently have a suspended timber floor (150mm joists), with 100mm rigid insulation and wet underfloor heating system with 50mm dry mix infill to take level with top of joists in my kitchen. This is covered with 18mm chipboard and I think approx 8mm ply. It was installed approx 10 years ago and has had 600x600mm porcelain tiles on top. The floor has had issues with tiles cracking and coming loose. Some of these were lifted including the adhesive removed and relaid several years ago and the same thing has happened. My view is that there is too much movement in the floor for the tiles even with a flexible adhesive. I would like to change the floor covering to vinyl tiles as they may be able to accommodate more flex. My thinking is that the tiles could be removed and a self levelling flexible screed poured ontop of the existing adhesive then vinyl laid on top, would this work?

    Other option would be be to lift the existing tiles and break up the adhesive (nightmare job) and either lift the top layer of plywood or leave it in place and then pour self levelling screed. With a kitchen including island installed in the room Id rather not have to rip up the entire floor structure to start from scratch with the floor.

    Has anyone had similar experience or offer any words of wisdom with other options or possible solutions. I am looking to get some pro's round to have a look but from initial enquiries not many interested. Im happy to do allot of the rip up myself which might make more appealing for someone to relay. Can offer more info if it helps with with possible solutions.

  2. merit

    merit Well-Known Member

    I wouldn’t want to bond to that. You could level it all with a flexible levelling compound and then put a heatpak or Jumpax over it. If the tile adhesive is well stuck after all the walking and tile removal you could probably get away with latexing over it. Or you can grind it off
  3. tarkett85

    tarkett85 Well-Known Member

    Personally I’d want to rip the lot up, replace the chipboard with ply, overboard with sp101 fibre screed then put the LVT down, although the proper answer is to remove the lot and screed the concrete. Chipboard isn’t dimensionally stable enough for ufh it’ll consistently flex and warp with it, the jumpax option would work although you will be adding even more resistance to the ufh.

    Sent from my iPhone using Tapatalk
  4. Sir Mick Henry

    Sir Mick Henry New Member

    It seems like you're dealing with a challenging flooring issue, and I can certainly provide some expert guidance on this matter.

    Firstly, the problem you're experiencing with cracked and loose tiles on your suspended timber floor could indeed be related to excessive movement. Timber floors can naturally flex and expand over time due to changes in humidity and temperature, which can impact the stability of tiles, even when using flexible adhesive.

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