DPM required? Which screed?

Discussion in 'Subfloor Preparation' started by MadGolfer, Aug 23, 2012.

  1. MadGolfer

    MadGolfer Member

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    Hi everyone,

    New to this site and have previously used a different one which doesn't seem to work anymore.

    Been to look at a job today which has a newly laid concrete floor with underfloor heating, water and not electric. Customer is wanting LVT.

    First question is can i still use a dpm with underfloor heating and should i? Readings are currently through the roof as its new.

    Second question is will i have to use Fball 700 flex or can i get away with 300hd?

    Appreciate your time everyone and look forward to the advice.
     
  2. Matt

    Matt Well-Known Member Staff Member

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    you cant use a surface dpm over underfloor heating. You need to let the concrete dry normally. As for compound you can use pretty much what you like.

    Welcome to the forum.
     
  3. merit

    merit Well-Known Member

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    Tremco do a dpm that can be used over ufh, but I've always been told ufh can crack the screed before its fully dry so best not to use one
     
  4. merit

    merit Well-Known Member

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    Also do you know if it's anhydride or Portland cement type screed?
     
  5. Matt

    Matt Well-Known Member Staff Member

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    Merit, there are a few that say you can. But trust me, we do masses of inspections on failed DPM systems. They all have that get out clause in the warranty.
     
  6. merit

    merit Well-Known Member

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    I can believe that
     
  7. Matt

    Matt Well-Known Member Staff Member

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    if only i was allowed to post up the pics and the product names...... sadly i cant as all court cases.
     
  8. MadGolfer

    MadGolfer Member

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    Hi Matt and thank you for the info.

    Do you mean i will have to let the concrete completely dry before i do anything with it and if so what is recommended? Other thing is Matt, should i get the customer to turn the underfloor heating on know to help dry out the new floor?

    Thanks again.
     
  9. NathanKing

    NathanKing Well-Known Member

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    I'm not 100% but I'd say turning the heating on would help speed up drying out but if not I'm think it's 1inch of concrete will take 1 month to dry out, at least that's what I've been told by a builder in the past.

    If it were me I wouldn't lay screed untill fully dry just incase it went wrong.
     
  10. MadGolfer

    MadGolfer Member

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    Hi Merit, it would be a Portland cement screed.

    Many thanks
     
  11. Matt

    Matt Well-Known Member Staff Member

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    yes you can run the heating as normal. Then take moister readings.
     

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