DIY_Doctor

Great thanks, I think I'll go down that route. Can I also ask anyone about how to finish the wall VCL to the ground as seen in this sketch of what I'm doing. If I leave it 'open' at the bottom, vapour could still pass behind it via underneath (as I'll need to keep the batten/plywood off the floor). If I run the wall PIR to the ground and follow the VCL over it and tape it to the ground, would the water vapour not theoretically drip down the VCL and leave drips on the edges of my flooring?

Thank you both for replies. @markcThe reason I want to seal it at the walls is to prevent moisture findings its way up the sides of the DPM. I guess if I was just laying the subfloor in isolation, it wouldn't matter to allow water vapour up through the sides and probably even preferable to allow it to go somewhere rather than pool beneath the slab and DPM. I have some contact adhesive left over from doing the EPDM roof perimeter - it says it will work on masonry and concrete if you think this would do the trick? @crispy_waferThat looks a good shout with the butyl tape. Most places I've read don't mention using heat to stick it but I imagine that will help with adhesion? Do you have experience of it sticking to rough surfaces like concrete block as once down, I won't be able to check if its come loose? Some places suggest also mechanically fixing with 'christmas tree' fixings.

Hi all, Hoping for some advice. Am converting a single skin block outbuilding into a utility room. There is a DPC above the first course of blocks but unlikely to be a DPM in the existing floor concrete slab. My plan is to lay down DPM and put 50mm PIR over this followed by P5 chipboard (then maybe LVT). Any ideas how to run the DPM up the side of the bottom of the walls up to the existing DPC level? What would you use to stick it to the wall? Will be battening the walls for insulation slabs in between and then plywood lining. Thanks