Prepping concrete subfloor, rising damp, appropriate DPM

Discussion in 'Subfloor Preparation' started by frogdad, Jan 11, 2024.

  1. frogdad

    frogdad New Member

    Maisonette built early 70s, end terrace backing onto garages. Am considering replacing flooring on ground level but need to resolve an issue with rising damp where concrete sub-floor meets garage wall (I don't have access to the garages). As far as I can see no DPM over concrete floor or DPC in garage wall (breeze block construction). I would like to fit floating cork floor and upgrade floor insulation as concrete subfloor makes it cold underfoot. Builder has advised me to retrofit DPC into garage wall, bitumen seal the junction between concrete subfloor and the breeze block garage wall and then cover the same junction with non permeable DPM sheet. Based on own research I suggested DPM would need to be extended to cover the whole ground floor plate before wood floor is laid but he suggested to only do it at this join where the rising damp issue is and let concrete breath elsewhere. This is different advice to what I've read elsewhere but he was adamant and has done good work for me in the past so I'd like to trust him but it just doesn't sound logical to me.

    This photos shows where I cut away the damp plasterboard to reveal wall construction. As you can see stud sole plate rests directly on subfloor and was wicking moisture up and into wall.

    Very rough section elevation to get a better sense of block construction as it is atypical and restricts what I can do in terms of access. Red circle is where photo was taken.
    Screenshot 2024-01-11 at 15.52.44.png

    If further detail is required I'll try my best to provide. Can't afford to start getting into digging up the whole floor so am wondering if I should save my money, mitigate the damp issue as best I can with venting to improve air flow and live with it until we move elsewhere, or whether there's a reasonably straightforward solution to fix damp and have nice insulated floors without worrying about damp coming back and ruining them!

    Grateful for second opinions and advice, thanks!
  2. Rugmunching

    Rugmunching Well-Known Member

    Piss off weirdo
  3. mjfl

    mjfl Well-Known Member

    If you can't afford doing right then just leave it as anything you do with it will wasted time and money.

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