Hello everyone. I recently bought a brick house built in 1890 that had a sagging kitchen, causing the tile to crack. I demoed the old kitchen, hired a Contractor to fix the support issues and he has installed new OSB subfloor. With the new subfloor we are a little over 3/4" off the wall. I am doing the tiling myself (ceramic) and he recommended that I use 1/4 inch Cement Board (mainly for height) and then put a ditra mat on top of that. He said since my house is so old it will continue to move. So he admitted the cement board will not help structurally but thought that plywood would be more likely to shift over the OSB. So the cement board would get us the height, and the ditra mat would do what it could to prevent cracking. After looking around on the internet this definitely seems like an uncommon solution, and in some corners ill advised as ditra only has instructions for installing on top of plywood or concrete (he did strongly suggest using the Schulter modified mortar). What do people around here think? Is ditra on top of cement board a no go for anyone?