My First DIY Tiling Job: Floor Preparation

[Chris Gorman]

So I have a duplex, and am currently renovating our tenant side. The last 2 big projects are to refinish the oak floors in the living room/bedrooms, and we want to tile the kitchen and bathroom. We're hiring out a contractor to refinish the wood floors and decided to take on the tile work DIY. I've never tiled a floor before.

After ripping up the 3 layers of old laminate & subfloor in the kitchen/bathroom there is oak floor there as well. 

All the DIY tiling videos I've found on YouTube have people applying thinset on a subfloor and then screwing down cement board to the subfloor. I initially though, am I going to need to fasten new subfloor to this oak floor in the kitchen/bathroom, then use thinset to install cement board on to that? There would be such a height difference between the tile and the refinished would floor... I spoke to a buddy who's father-in-law is a contractor. He said to install a subfloor on to the oak and I can tile right on to the that, which I was skeptical about. So I go to home depot to pick up subfloor materials and tell a rep there what my plan was. Home Depot said not to tile right on to subfloor. They said I could screw down cement board right to the oak floor and not have to use thinset. Is this appropriate? I've already picked up the cement board.