I am preparing to do a kitchen remodel where I am replacing an existing tile floor with a new porcelain tile floor. The old floor that is being replaced has several areas where it is not level and some areas where the old tiles have cracked, possibly because the sub-floor is not stiff enough.
I am interviewing contractors to do this work and I really want a high-quality installation, even if I have to pay more for it. I have a book about remodeling by that TV guy Mike Holmes and he says that the proper way to prep a subfloor for tiles is:
First, make sure you have a 1 1/4-inch sub-floor before any tile goes down. That means if there's a 5/8-in layer of oriented strand board, then you need at least another 5/8-inches on top of that. Use oriented strand board, conventional plywood, or better yet, a waterproof product like WonderBoard or HardiBoard which are concrete-based products. Whatever you use should be set onto the existing sub-floor and glued and screwed to the joists underneath. Finally, I recommend a waterproof membrane on top of that such as Ditra from Schluter. It's a bright orange waffled plastic that's put down right before laying the tile. It helps with water-tightness and provides just a little bit of flex, which allows the tile to absorb impact.
I have prepared a scope of work describing that I want this done and sent it to some local tile laying companies for quotes. The responses I have received have indicated that this is not the way they would recommend prepare a floor for laying tile and they recommend alternatives. After I received those responses I went to a tile store and asked about this and they also said not to do this.
I have three questions
- Is the way described in the book a good way to prepare floor for laying tile?
- Why would he write this in his book if it wasn't a good/standard way of preparing the subfloor?
- If you were having a tile floor installed in your house what subfloor preparation would you want assuming you are looking for the highest quality installation?
I guess I am also wondering why I am getting pushback on this from the installers?