How to lay new ceramic tile over old tile
1 of 3Photo 1: Grind off high spots
Lay a level on the old tile and mark any high spots. Grind them down with a grinder.
Roughen the tile with 80-grit sandpaper.
2 of 3Photo 2: Spread adhesive
Spread a flat layer of thin-set on the
back of large tiles for better adhesion.
Or, use a larger-notch trowel.
3 of 3Photo 3: Set the tile
Press the tile onto the floor thin-set
and slide it perpendicular to the
combed lines.
If your old ceramic tile is worn or dated, you can lay new tile right over the old, and avoid the huge job of tearing out the old tile. This assumes that the floor underneath is solid (concrete) and that there are no cracks in the
existing tile (indicating underlying
problems in the concrete). In fact, pros do it all the time.
Surface preparation is paramount.
Start by making sure all the tiles are
solidly bonded to the floor. Tap them
lightly with a wood mallet or a chunk
of 2x4. A hollow sound is an indication
that a tile is loose. Remove and reset
any loose ones with thin-set. Next, use
a 4-ft. level to find any high spots and
grind those down using a right-angle
grinder with a masonry wheel. Then
sand all the tiles with a belt or orbital
sander (80-grit) to scratch any surface
glazes. Remove any moldy or loose
grout with a rotary tool or carbide
scraper. Vacuum the tiles and clean
with detergent and water to remove
dirt, sealers and wax. Rinse the surface
with clear water and let it dry.
Buy a latex-modified thin-set (one
brand is FlexBond) and mix it in small
batches to keep it from skinning over.
Complete adhesive coverage is critical
on large tiles (12 in. or larger) and even
more important when you’re tiling over
tile. Some installers prefer to “flatback”
each tile with the flat edge of the trowel
before applying the tile to the combed
thin-set. Others prefer to use a larger notched
trowel (1/2 x 1/2 in.) to apply
the thin-set. Whichever method you
use, always comb the adhesive in one
direction (no swirls). Then set the tile
on the floor and slide it perpendicular
to the combed thin-set to knock down
the rows and spread the adhesive.
