Wondering what has gone wrong or is it wrong?
I am applying real stone veneer on an interior wall as a hearth around a gas stove. I demo'd the sheetrock and screwed cement board on the studs. I applied a scratch coat of S mortar over the cement board and allowed it to dry at least 48 hours.
I have been buttering the stones and then sticking them to the wall and all has been fine. It seems that at the 6 foot mark on the left side of the wall one of my stones is loose. Upon further inspection it is not just the stone/mortar not setup properly but the scratch coat it has adhered to seems to not have adhered to the cement board.On further inspection the scratch coat in this area did not stick to the cement board!
What could have cause this? Something on the cement board not allowing the mortar to stick? Was my S mortar mix too dry when I applied it? Too wet?
Can I just peel this defective layer off and re-apply a new coat over the cement board?