How Do I Add Cement Board to a Wood Subfloor?

  • Transcript

    LESLIE: Now we’re heading over to North Carolina where Chris has a question on flooring. What can we help you with today?

    CHRIS: I had a leaking toilet that rotted my wood subfloor. I ripped it all up and I put the new pieces of wood back down.

    TOM: OK.

    CHRIS: Well, my cuts weren’t exactly perfect and there’s some spacing in between, like maybe 3/16.

    TOM: Yeah, that’s pretty good.

    CHRIS: OK. It’s just in some sections. And I’m going to put down the ¼-inch cement board to put tile down here.

    TOM: OK.

    CHRIS: And I just wanted to know: what type of mortar do I use to put the cement board down onto this wood subfloor? And then once the cement board is down and it’s screwed in, do I have to put some type of mesh tape to put the boards together and then mortar the tape?

    TOM: No. So, first of all, if you’re going to put down DUROCK, which is sort of that cement board that you’re describing, generally, that’s screwed down. So you would screw that down to the floor. And then on top of that, you would apply the adhesive for the tile. And you’d glue the tile right to the board.

    CHRIS: OK.

    TOM: Having those gaps in the plywood repair is no big deal because that’s all going to be covered over. Just make sure that when you put the cement board down that you don’t align the seams of the board with any of the old seams of the plywood below it.

    CHRIS: Right.

    TOM: Everything should overlap.

    CHRIS: Do I still have to put the mesh tape, though, for the boards – the cement boards – or no?

    TOM: Yeah, I don’t think so.

    CHRIS: OK.

    TOM: I think you can go right on top of that. As long as you have good adhesion of those boards down, they’re secured well in place, they shouldn’t move.

    CHRIS: OK, great.

    TOM: Chris, good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.

Leave a Reply


More tips, ideas and inspiration to fuel your next home improvement, remodeling or décor project!