Sandy , i walked away from a 300m2 heated screed floor recently because the bloke dithered on using a decoup mat , if the tiles start cracking you can be sure your in the mire because you knew but went ahead anyway, who needs the hassle ??My other issue is they may wish to proceed without decoupling. My intention is to quote decoupling separately with a recommendation to using it. If they go against my advice and I proceed without decoupling I'm concerned I would still be held liable if the tiles fail as my quote would prove I was aware of risks involved of not decoupling. I'm thinking of wording it as a recommendation to lower risk and should they instruct me to proceed they would be accepting the higher risk. Does that makes sense?