Does my concrete floor also need liquid damp proof membrane adding before adding a self leveling compound if the floor already has a DPM sheet underneath it. Its a 75mm thick concrete that has been allowed to dry over 4 months.
Thanks KIAB. I was reading the manufacturer instructions on the leveling compound and it mentioned addind a Liquid Damp Proof so just I just wanted to make sure. It must have been referring to slab laid on top of soil without a sheet. Cheers.
But, I can see the sense of the manufacturer instructions recommending a liquid dpm,it does gives you a second level of defence, if your dpm,unknowingly got punctured during installation, or the floor is old & there a risk or signs of old dpm failing, or your unsure there is one present.
Unless you specifically need it, I would leave off the DPM. Some DPM products have aren't the best things to stick to even with a primer as they have some flex in the product and can have a greasy feel to them. Floor leveling compound can become flaky in places where it fails to adhere to floor surfaces. I had to fix leveling compound where it has failed to adhere in places and gone flaky and it is a real pain to put right, so I try and keep as few things to go wrong as possible. Where people have been walking over the floor, give it a quick rub over with a sander or angle grinder just to scuff up any ingrained dirt and grease
I already have the liquid DPM so it wont cost me any more to do so I've been using Black Jack liquid DPM and have noticed it is in fact has a greasy finish. I'm going to take your advice on this on 'sospan' and keep it simple. Clean, prime then self level, Thanks as always