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  1. Aki Nawaz

    Aki Nawaz New to

    West Midlands
    Hello everybody.

    My first post on here; any advice and pointers greatly appreciated.

    Ground floor extension c45m2.
    Wet UFH system under 50mm of calcium screed (thermio plus).
    Screed went down 4 weeks ago (sanded down after 2 weeks).
    Final tile is a 600 x 300 porcelain.

    I have had several tilers around and am getting conflicting views on how to approach this job. One tiler has said that ditra matting is a must between the screed and tile. While others have said not required. Also seem to be variation in the adhesive; some say a cementious one as ok; others not.

    Any thoughts on the need for ditra matting, the type of adhesive and any other pointers are very much appreciated.

    Thanks in advance.
  2. Glynn

    Glynn Company Support

    The tiling of these screeds is dictated by moisture levels in the screeds and this process cannot be short cut. Moisture readings MUST be taken with a suitable metre. We would always recommend the use of a gypsum based adhesive as you remove the chance of ettringite forming which will cause the tiles to fail. For a gypsum adhesive it needs to be below 85%RH (relative humidity).Cement based adhesive can be used but not till the screed is below 75%RH. Theses screeds will always fail if short cuts are taken. If you or any one else contact me at Tilemaster I will email you our full specification for preparing and tiling to an anhydrite screed. I will repeat myself "this process cannot be short cut". Ditra is always recommended onto under floor heating but with porcelain we do not insist on it if you are using a good quality gypsum adhesive.
    • Like Like x 4
  3. Aki Nawaz

    Aki Nawaz New to

    West Midlands
    Thanks Glynn. I was aware of the moisture levels needing to be below a certain point. Thanks for reiterating and emphasising how critical they are to ensure the job is a good one. Have had a quick look on your website and have also sent you an email. Thanks again.
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