Tiling a Basement Floor
Do I have to sand paint off my basement floor before tiling it?
I'd like to tile my basement floor, but there's a coat of paint over it. Someone told me I'd have to sand the paint off. Is there any alternative that's not so messy, or should I go to another type of flooring?
— Daniel, Mineola, N.Y.
Joe Ferrante replies: Sanding would be a big mess, that's for sure, and even then you can't be sure the tiles will hold. Here's what I would do.
Scrape off any loose paint, then scuff up what remains using a pole sander and 80-grit paper. Vacuum up the dust. Now use a notched trowel to spread thinset adhesive mixed with a latex additive over a section of the floor. Place a sheet of 1?2-inch cement board into the adhesive and beat it into place with a wood block and a hammer. Keep spreading thinset and bedding sheets of cement board until the entire floor is covered. Be sure to stagger the boards and cover the joints with a layer of fiberglass reinforcing tape and thinset. Leave the floor alone for several days, then tile it following standard methods.
Even if the bond between the thinset and the basement slab eventually fails, the boards will "float" in place and the tiles will stay secure.
Joe Ferrante is a tiling contractor in Massachusetts who has worked on many This Old House TV projects.