I need a solution to holes made in DPM below concrete sub floor
My project is an underfloor heating system installation.
Most of my ground floor is wooden joists, and this area has not been problematic, however, the extension part of my home has a concrete subfloor with scree on top.
MY plan has been to remove the scree, approx 50-70mm depth, from much, but not all, of the extension floor area, fasten down wooden battens, then place the foiled polystyrene panels that will hold the water pipes between battens and fasten plywood then wood flooring on top, using battens as fixing points for the ply.
I expected the concrete to have quite a bit of depth to it, with a damp proof membrane below...however, I have now discovered that the concrete, which was laid about 40 years ago, is only about 50mm deep, with a plastic membrane below it, then more loose materiel, including sand below.
Unfortunately, many of my fixings for the battens have pierced the membrane, which seems to have damp sand below it.
I will now remove all battens and fixings.
Is there a product which can be poured onto the surface of my concrete sub floor, or ideally, just squirted into the holes, which will seal the puctures I have made in the membrane, or at least prevent damp/moisture form spreading into my floor.?
I can enlarge the holes slightly if necessary to reveal a bit more of the undamaged membrane around my punctures !
As far as I can tell, there was not previously a problem with damp, but I suspect the holes I have made will cause big problems if ignored.
I do not particularly need to level off the area, i just need to seal the holes against damp.
thanks in advance for your time