My basement concrete slab has been cut to add some plumbing. Problem is that it was cut in such a way that there are no existing vapor barrier left to tie new ones into. Attaching photos for better understanding.

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enter image description here So the best I can do is just sort of lay it on there. What else can I do here?

I'm going to be putting on dricore on top of concrete slab anyway, should I not worry about vapor barriers?

  • That's a DPM, not a vapour barrier. It stops rising damp - so long as you have a continous barrier between the soil and your floor it's fine. The pics are a bit too small to figure out what your problem is/ how we can help out. Commented Apr 9, 2022 at 22:27
  • Thanks. The problem is I'm having difficulty having a continuous barrier since there isn't existing barrier to tie into anymore. Cutting the concrete also cut the existing barrier flush. Would having a new layer just sort of floating help with moisture at all? Commented Apr 9, 2022 at 22:43
  • If you cannot seal the plastic don’t waste $ on trying if water can get above the plastic the concrete will wick it up if you don’t have a high water problem sealing with epoxy will stop humidity. Putting a piece of plastic down helps and this can be a standard trash bag with such a small area. If you do have high water hydraulic cement is a good choice . I have seen a lot of $ spent on failed seals for similar jobs where water came right through the cut line. I drill holes in the sides and put 16 penny nails they act like rebar I have never had a patched slab slip later but have fixed them.
    – Ed Beal
    Commented Apr 9, 2022 at 23:07

1 Answer 1


Liquid DPM

The plastic barrier there is a damp proof membrane and its job is to prevent rising damp. Older properties don't have one of these resulting in that infamous damp basement smell. To repair a hole through a DPM, use a liquid DPM around the edges of the hole and then your new DPM patch can be effectively stuck on to it, allowing the barrier to remain continous without having to dig up more of the slab.

Alternatively, double sided jointing tape around the edges of the hole would also allow your barrier patch to stick to it as well, however, from experience of using this kind of tape, it's extremely awkward just given how sticky this stuff is.

  • Thanks. Liquid rubber will do the job just the same right? Commented Apr 10, 2022 at 2:30
  • 1
    @basement_diy Yes - "sticky, flowing and waterproof" is essentially what you need, so if you already happen to have something that fulfils those criteria then all the better :) Mainly just want to make sure it gets right into the corners of your cutout for the best protection. Commented Apr 10, 2022 at 2:39

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