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Do I need DPM under insulated formed floor?

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  • 10-09-2010 1:22pm
    #1
    msft
    Closed Accounts Posts: 11 ✭


    We are hoping to use an insualted formed floor foundation like Viking, IsoQuick or Styrofoam systems.
    I was just wondering if anybody knew if I need a DPM layer under the insualtion or is the EPS insualtion damp proof?


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    #2
    heinbloed
    Registered Users Posts: 1,632 ✭✭✭heinbloed


    A damp proof course is strongly recommended.
    This would have to be placed over the EPS, better between the layers of the EPS to protect it against puncturing.
    Another method - faulty but frequently seen - is to put the DPC under the EPS, but this is problematic. It should be avoided to create a sink or pool under the EPS where water from direct ingress or caused by condensation would acumulate.


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    #3
    msft
    Closed Accounts Posts: 11 ✭msft


    Good point. Had never considered the collection of water which cannot escape thru the dpm. So if I use a 1200 gauge radon/dpm layer above the below the top layer of insualtion (100 insulation, dpm, 200 insulation), that should do the trick!
    Can the radon and the dpm double up?


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    #4
    heinbloed
    Registered Users Posts: 1,632 ✭✭✭heinbloed


    Had never considered the collection of water which cannot escape thru the dpm. So if I use a 1200 gauge radon/dpm layer above the below the top layer of insualtion (100 insulation, dpm, 200 insulation), that should do the trick!

    Yes. This build-up would also very likely keep the dew-point beyond the habitated area, under the DPM. For a dew-point analysis contact your architect or builder or the like.

    The DPC can act as a radon barrier, check the manufacturer's instructions.


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