Q: We're about to replace the ceramic tile flooring in our bathroom. Can you tell us how to remove the old tiles, and what we should do to ready the area for new tiles?

— Joseph, Des Plaines, IL

A: Joe Ferrante replies: You're brave — that's a big job. But there's no reason not to tackle it. First, you need a clear floor area to work with. Take out the toilet and any pedestal sinks and disconnect all the water pipes or drains that go through the floor.

If you don't know what's under your tile, you'll have to do some detective work to find out whether it's plywood, cement backerboard, or a thick bed of mortar. Put on some safety glasses and leather work gloves; broken shards of tile can slice skin like a knife. Then grab a cold chisel and a three-pound sledge. There's nothing subtle about breaking through tile. Just pick a few in the middle of the floor and whack away until you can see what's underneath.

If it's a mortar bed, chisel down through the bed to the tar paper, then use a big flatbar or similar demolition tool to pry up chunks of mortar and tile. It should come up fairly easily.

If the tile is stuck to plywood, the strategy is a little different. Chip out a single row of tile down the length of the floor and another row across the width, with the intersection of the two rows somewhere in the middle of your floor. This will expose the plywood underlayment. Now fit a reciprocating saw with a 12-inch-long wood-cutting blade and make a shallow plunge cut into the plywood. Just as the blade starts to cut through the plywood, pull the saw toward you and make a continuous, low-angle cut just through the plywood underlayment, not the subfloor. (As awkward as a reciprocating saw may seem, a circular saw is actually harder to control and kicks up too much dust.) Once you've finished the cut, work your flatbar under the underlayment and rip it up, tile and all.

Tile that's attached to cement backerboard needs the same kind of treatment as tile stuck to plywood. Just use a recip saw with a carbide-grit masonry cutting blade and work in one small area at a time. If the backerboard is glued down, the plywood subfloor may be damaged during the removal process. Any panels that are damaged will have to be ripped out and replaced.
(Joe Ferrante is a tiling contractor who has been working on This Old House projects since 1986.)
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