Waterproof top coat over calcium sulphate??

Discussion in 'Subfloor Preparation' started by Mwfloor, May 3, 2018.

  1. Spacey

    Spacey Super Moderator Staff Member

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    That product in the link is new fast setting concrete The one in your pics looks like Calsium sulphate?

    Do you think you could have the right manufacturer just the wrong product link ?
     
  2. Mwfloor

    Mwfloor Well-Known Member

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    I asked the builder exactly who and what screed it was, I took this picture of his phone showing the people who did it.. so it is what they say but it looks and acts very similar? [​IMG]


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  3. Spacey

    Spacey Super Moderator Staff Member

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    Well having completely no trust in what builders say or do when it comes to anything flooring related I would still treat it as Calcium sulphate and use Calcium sulphate based products on it to be safe
     
  4. dazlight

    dazlight Super Moderator

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    Need to do the milk test on it. Full fat not semi remember
     
  5. merit

    merit Well-Known Member

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    It’s a liquid cement. Same as the one we had that cracked in the same way. No Laitance and dries quicker but cracks like mad when you turn the heating on! They guaranteed us it wouldn’t crack or move anymore so we filled the cracks and screeded over it. No problems so far but was only around 6 months ago!


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  6. Mwfloor

    Mwfloor Well-Known Member

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    Did you still grind it down?


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  7. merit

    merit Well-Known Member

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    No mate. Didn’t need it


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  8. merit

    merit Well-Known Member

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    It’s defo dark enough to be liquid cement. Would of thought a dpm would of been fine if it was tho?


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  9. merit

    merit Well-Known Member

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    To be fair they said it didn’t need grinding but if I had a grinder I would of given it a once over! Looked a bit patchy!!


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  10. coolevilangel

    coolevilangel Well-Known Member

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    Is there Independant zones for the ufh?
    I’m not seeing any expansion joints?
     
  11. Spacey

    Spacey Super Moderator Staff Member

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    Can’t you see ?
    Mike it forms it’s own expansion joints as it dries :rolleyes:
     
  12. Mwfloor

    Mwfloor Well-Known Member

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    I'm unsure tbh, if there isn't any expansion joints.. who's job would it if been to have them in place.. like I say this isn't my job I was just helping out today but I like to know for future reference. And it might help out other folks who read this


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  13. coolevilangel

    coolevilangel Well-Known Member

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  14. Spacey

    Spacey Super Moderator Staff Member

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  15. Mwfloor

    Mwfloor Well-Known Member

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    lol nah! But I might make a tea with some whole milk tell me how this test works again?


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  16. Matt

    Matt Well-Known Member Staff Member

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    That's not Calcium. That is a cement based flow screed. They claim to dry quicker, well yes they do, they harden quicker! Not dry as in fit on quicker. They also apply a curing agent to the surface to stop it drying out to fast. This has to be removed by grinding. The cracking will be down to it being poured and then sunlight hitting it within the first 48 hrs. Not really something to worry about as it should have rebar running through it. I will presume it is over a block and beam subfloor? These products are not new. Been around a good 4 years now in U.K. Agillia type c for example.
     
    Last edited: May 3, 2018
  17. merit

    merit Well-Known Member

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    Good to know it needs grinding. We were told it didn’t but it was a pretty inconsistent finish.


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  18. merit

    merit Well-Known Member

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    Can you use a liquid dpm on these?


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  19. Spacey

    Spacey Super Moderator Staff Member

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    4 years is pretty new tbf lol

    Agillia is weird stuff almost looks like wax
     
  20. Matt

    Matt Well-Known Member Staff Member

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    Yes, you can DPM them, but only after grinding it. As for the cracks, mix a pu based dpm with sand and pour down cracks. The moisture in the sand will cause the PU to expand and it will fill and glue the subfloor together. Scrap off excess that foams out the top of the crack.
     

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