Preparing the Kitchen Subfloor For Tile
Saturday, December 15th, 2007Well, it’s time to prepare the kitchen subfloor for the tile that’s going to be going on top of it.
Some people have told me, “Hey, just lay the tile on top of the plywood…it’ll be fine.” I was always a little uneasy about that, so I read up on it. Apparently, it’s not a good idea to adhere tile right to plywood, because wood shrinks and expands with temperature and humidity. I guess you can do this in your house if you feel like doing the whole job over in a few years.
The way I like tile done in our house is to prep the subfloor, put thin-set over the subfloor, lay down cement board over the thinset and nail/screw the cement board down. Now, put your tile down. The cement board is what you want to adhere your tile to, not the subfloor.
So last night I started prepping the subfloor for the tile. The first thing I did was to head down to the basement. As you may know, there are several joints in the subfloor. Many of them travel with the floor joists, so they aren’t a big concern. We’ll call those “vertical” joints or seams. Then, there are other joints…we’ll call them “horizontal” joints. These seams travel across the floor joists and have nothing holding them from flexing. Well, I suppose they are tongue and groove, but from what I can see, they still flex when I stand on them. I good way to see if they flex is to walk around with bare feet. You can feel around better.
You can see the seams in the photo above.
When I went downstairs, I pulled out my nice new DeWalt miter saw and grabbed some spare 2″x4″s. My plan was to cut the 2″x4″s and screw them up against the bottom of the subfloor (screws into the existing joists). There was insulation in the way, so I tried to be very careful…I had just gotten out of the shower. Well, everything was going fine. I was cutting and screwing and cutting and screwing. Then, I started noticing some itching on my arms. Man!!! The insulation got to me. Oh well, there’s another shower.
Anyway, the purpose of those 2″x4″s is to stop the flex from those horizontal seams. I went upstairs and I succeeded in my mission. I walked around bare-footed and everything was good and solid. Now, I had something to screw into to finish off that job.
Also, when preparing a subfloor for tile, you want to be sure to re-screw the subfloor to the joists. Things are bound to come loose and start squeaking over time. If you walk around, you may even notice some play between the subfloor and the joists. Some hopping might help you notice this. This is the reason I went out and bought my new chalk snapper.
Luckily, in my case, the previous owners put down some really cheap parquet flooring. They came in 1′x1′ squares with foam attached to the bottoms. On the foam, there was adhesive. This adhesive left me with little glue spots all over the floor. Now, I don’t only have to sand the floor smooth, I also have to sand up the glue spots, which like to get sticky when hot (from the friction of the sander). We’ll see how that goes.
After the floor is all sanded, I am going to re-screw the subfloor to the joists and sweep up. The floor will be ready to tile and my job is done.
