How to Add Decorative Rows to a Subway Tile Backsplash

Determine which existing tile rows you want to replace with decorative tiles and mark them with a grease pencil.

Use a grout saw to cut around the tiles to be removed. Go slowly and saw carefully until all the grout is gone. Be careful not to scratch the surrounding tiles that are remaining. Remove every last speck of grout from around the tiles to be removed; the blade of the saw should fit all the way down to the backer board, and there should appear to be a cavity around the tile.

Tap the tiles to be removed with a hammer until they crack. The cracked tile may fall out by itself, or you may have to use the claw side of the hammer to gently work it loose. Do not use adjoining tiles for leverage, or they may crack or chip. Don't swing the hammer; just tap. You only want enough force to affect the one tile you're working on.

Remove all unwanted tiles in the same way, and use a chisel or flat-head screwdriver to remove bits of mastic that may still be stuck to the backer board. Be very careful not to chip any surrounding tile. Remove all mastic; the backer board must be completely flat for the new tile to sit correctly.

Clean the area with a large, dry paintbrush to remove bits of tile or grout that could interfere with tile placement.

Apply mastic to both the back of the new tile and the area of the wall to be tiled, and scrape both with the serrated edge of the trowel.

Place the tile as desired, pressing firmly to ensure a firm bond. If your new tile is not self-spacing, use plastic tile spacers along each edge of the tile. Be sure the spacers are the same size as your existing grout line.

Stand back and observe the new tile from a distance. Make sure lines are straight and corners are even, making corrections as necessary. Allow it to dry overnight.

Apply grout to the new tile, using the float to press it into the grout lines. As you work, periodically go back and use the edge of the float to scrape away excess grout on the tile surface; don't dig into the grout lines. Allow it to dry until it's set but still damp. This could be as little as 10 minutes or as much as 30 minutes, depending upon the climate.

Wipe the tile lightly with a slightly damp tile sponge and clean water. Focus on removing the haze from the tile surface and try not to disturb the grout lines too much. Allow it to dry for another 20 minutes or so.

Wipe the tile with the sponge again, this time using a wetter sponge. Wipe along the grout lines to smooth them, and generally refine the width and depth to match the existing grout lines. Allow to dry until set, usually overnight.

Wipe the tile surface with cheesecloth to remove the remaining haze, and apply grout sealer according to the instructions on the bottle.