I'm remodelling a 300 year old house and want to install limestone floors in the bathrooms. The floor joints are 3 x 8 and on 30 inch centers (as opposed to modern 16 inch centres)
I have removed old flooring. Can I get away with using a thicker subfloor (e.g. 1 inch ply + cement board as opposed to using 3/4 inch ply + CB) or should I use 2x8 stengthers running perpendicular between each joist?