Hi i have an outbuilding that has a damp concrete floor, i know that my builder put dpm underneath the concrete but i think that something has gone wrong and i have told my builder to go due to some problems we have had. I have heard that he was supposed to do finishing on the surface but he has not. Can i just put surface dpm on the surface then put self leveling compound on top of that will that solve the dampness and is that the right way round.