Preparing anhydrite screed

Discussion in 'Subfloor Preparation' started by oliver, Jul 11, 2019.

  1. oliver

    oliver New Member

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    Hi all, new member here and hopefully a straightforward question.
    We are fixing engineered oak to a new anhydrite screed with Sikabond MS. It has been sanded/grinded and the ufh commissioned.
    My question is does the screed need to be primed? The sanded surface is quite rough and I would guess quite porous.

    Also, the recommended moisture should be 0.3%CM. What would this equate to in %RH measured with a hygrometer box? I am guessing around 55% as 0.5%cm is roughly equivalent to 65%rh.

    Many thanks
     
  2. merit

    merit Well-Known Member

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    Yes you will defo need a primer


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  3. merit

    merit Well-Known Member

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    2 coats


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  4. oliver

    oliver New Member

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    Thanks Merit. The sika datasheet sYs one is not needed but I was dubious.
    Any recommendations, acrylic, epoxy?
     
  5. merit

    merit Well-Known Member

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    Acrylic as long as the subfloor is dry


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  6. mjfl

    mjfl Well-Known Member

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    Dilute first coat , neat second coat
     
  7. nevertrever2

    nevertrever2 Well-Known Member

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    Tramex told me that 0.3 was roughly 75% rh, we are waiting on a subfloor to dry to start a karndean installation
     

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