Install a Tile Backsplash Behind a Bathroom Vanity

Tile behind a vanity does two things well: it protects drywall from water splatter, and it lets you introduce color or pattern exactly where you want it. The space is small enough to finish in an afternoon, forgiving enough for first-timers, and visible enough that good work shows. A backsplash is four inches minimum, though most installers run it twelve to eighteen inches high or all the way to the mirror. The key is keeping your layout tight and your grout lines consistent. Done right, it looks intentional. Done poorly, it looks like you gave up halfway through.

1. Prep the wall surface. Turn off power to any outlets in the backsplash area. Remove outlet covers and protect outlets with painter's tape. Clean the wall with TSP or degreaser to remove soap residue and oils. Sand any glossy paint lightly with 120-grit paper so the thinset has tooth to grip. Wipe down with a damp cloth and let dry completely.
2. Mark your layout lines. Measure up from the vanity top and mark your finished height with a level line. Dry-lay your tiles on the counter to figure out where cuts will fall—adjust your starting point so you don't end with slivers at the edges. Mark a vertical centerline if you're centering a pattern, or start from the most visible corner if running a subway pattern.
3. Mix and apply thinset. Mix thinset to peanut butter consistency following bag instructions. Let it slake for ten minutes, then remix. Using a 3/16-inch notched trowel, spread thinset on the wall in a two-foot section, holding the trowel at a 45-degree angle to create even ridges. Work in areas you can tile within ten minutes.
4. Set the first row. Press your first tile into the thinset with a slight twist, using spacers at all four corners. Check it with a level. Continue across the row, inserting spacers between each tile as you go. Every few tiles, press a straightedge across the surface to make sure nothing is sticking out or sinking in.
5. Continue setting tiles and make cuts. Work row by row, checking level and plane as you go. For straight cuts, score with a tile cutter or snap cutter. For outlets or odd shapes, use a wet saw or angle grinder with a diamond blade. Butter the back of small cut pieces with extra thinset before setting them. Keep spacers in place until the thinset cures.
6. Let thinset cure fully. Leave all spacers in place and do not touch the tiles for at least 24 hours. Check your thinset bag for exact cure time—some need longer in humid conditions. After curing, pull out all spacers with needle-nose pliers or a utility knife.
7. Grout the joints. Mix sanded grout to toothpaste consistency. Using a rubber grout float, spread grout diagonally across the tiles, packing it into joints. Work in three-foot sections. After ten minutes, wipe diagonally with a damp sponge, rinsing frequently. Let haze form, then buff with a microfiber cloth. Wait 72 hours before sealing.
8. Seal grout and reinstall fixtures. Apply penetrating grout sealer with a small brush or foam applicator, wiping excess off tile faces immediately. Let dry per label instructions. Caulk the joint where tile meets vanity top with color-matched silicone caulk. Reinstall outlet covers and turn power back on.