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Radon in old house with new extension

  • 13-05-2022 2:08pm
    Registered Users Posts: 11 kerrytigin


    I am renovating a stone cottage, floors dug out and about to put in stone and a subfloor this week with the intention ( later ) on radon barrier ( over subfloor ) 6" insulation, UFH and screed. I then have a new extension built on to the cottage which will be 2 x bedrooms and toilet with inside block on flat up to finished floor level and the outside block on its side down x 1 block.

    I initially was not going to put in a radon barrier ( my reasoning being that the cottage does not have one and I question how it would protect as I obviously can't go under the stone walls )

    My ground worker suggested putting in a radon barrier throughout as it will also work as the dpc and that makes sense.

    We are not in a high radon area.

    So wondering your thoughts on

    A: putting radon OVER the subfloor

    B: How protected we will be when under the walls in the cottage section of the house will not have the radon running under ( guess we will still have it as dpc regardless ! )

    Many thanks !


  • Registered Users Posts: 751 ✭✭✭ C. Eastwood


    You can check if you require a Radon Barrier if you put in your Eircode in to this link:- (no space),

    If you are on a light or dark yellow square on the Map, then you do not need to fit a Radon Barrier.

    Your ground worker is incompetent to tell you to install a Radon Barrier if it is not needed. It is a waste of money.

    Fit a 1200 gauge DPM, on sand blinding on well compacted hardcore.

    Hardcore - T2 Permerable – 4-40mm gas permeable material of which a 200mm layer must be used where a radon sump is used (greater depth allowable if preferred to mixing gradings with T1 Struc)

    Inform your ground worker that a Radon Barrier Membrane is not a DPC (Damp Proof Course) - it is a DPM (Damp Proof Membrane).

    It is a requirement of the Building Regulations that you must install a Radon Sump and outlet no matter what colour square your house is in on the Radon Map.

    Its a Building Regulation and the Regulations are for the Health Welfare and Safety of persons.

    Hood Luck.