How to Install a Subway Tile Backsplash, Step by Step

A subway tile backsplash protects the wall behind your counters from splashes and grease, and it’s one of the most approachable tile jobs for a first-timer. The area is small, the tile is flat and uniform, and nothing structural depends on it. The keys to a clean result are a smart layout, careful work around outlets and patience with grout.

Difficulty: Intermediate · Time: A weekend (one day to set tile, one day to grout and caulk)

Tools and materials

• Subway tile (order 10 to 15 percent extra for cuts and breakage) and matching bullnose or edge trim if the backsplash ends in open wall
• Thinset mortar or premixed tile adhesive (mastic), see the note below
• V-notch or small square-notch trowel sized for your tile (often 3/16-inch V-notch for standard 3×6 tile)
• Tile spacers (1/16- or 1/8-inch) or self-spacing tile
• Level, tape measure, pencil and a straight board or ledger strip
• Manual snap tile cutter, plus a wet saw or angle grinder with a diamond blade for notches
• Tile nippers and a rubbing stone for smoothing cut edges
• Outlet box extenders and longer device screws
• Non-contact voltage tester
• Grout (unsanded for joints 1/8 inch and smaller), grout float, sponges and buckets
• 100 percent silicone or siliconized caulk matched to the grout color
• Safety glasses, gloves and a dust mask for mixing powders

Thinset or mastic

For a kitchen backsplash that won’t see standing water, premixed mastic is popular because it grabs tile quickly and keeps small tiles from sliding. Thinset mortar is the better choice behind a sink or range where things get wet or hot, for glass tile, and for larger or heavier tile. Read the tile manufacturer’s recommendation and follow it. Never use mastic in a shower.

Step-by-step

1. Turn off the power. Shut off the breakers for every outlet and switch on the backsplash wall, then confirm with a non-contact tester. Remove the cover plates. You will be working right next to live circuits otherwise.
2. Prep the wall. Clean off grease, scrape any loose paint, patch holes and lightly scuff glossy paint so the adhesive bonds. The wall should be flat. Check with a straightedge and sand down high spots or fill low ones.
3. Protect the counter. Lay down cardboard or a drop cloth and tape the counter edge. Thinset and grout scratch stone and laminate if they get ground in.
4. Plan the layout from the center. Find the visual center of the wall, usually the centerline of the range or sink window, and mark a plumb line there. Dry-lay a row of tile on the counter with spacers to see where cuts land at each end. You want cuts at the ends to be at least half a tile. If one end gets a sliver, shift the starting line half a tile.
5. Check the counter for level. Counters are rarely perfectly level. If yours drops more than about 1/8 inch over its length, screw a straight ledger board to the wall one tile height up, level it, and tile up from there. Fill in the bottom row with cut tile after removing the ledger.
6. Install outlet box extenders. Your outlets will need to come forward to sit flush with the finished tile. Box extenders bring the electrical box out to the new surface, which is what electrical code expects. Plan to reinstall devices with longer screws.
7. Spread adhesive and set tile. Work in small sections, about 2 to 3 square feet at a time. Spread with the flat side of the trowel, then comb with the notched side in one direction. Press each tile in with a slight twist. Use spacers between tiles and leave a 1/8-inch gap at the counter for caulk. Offset each row by half a tile for the classic running-bond pattern.
8. Make cuts. Straight cuts are fastest on a snap cutter. For notches around outlets, mark the tile, make two straight cuts with a wet saw or grinder, and snap or nip out the waste. Smooth edges with a rubbing stone. The cover plate will hide small imperfections, so the cut only needs to be close.
9. Check as you go. Every few rows, set a level on the tile and pull a tile occasionally to confirm you are getting good adhesive coverage on the back. Wipe off any adhesive squeezing into joints before it sets.
10. Let it set. Pull spacers once adhesive firms up and let the tile cure for the time on the bag or bucket, often 24 hours, before grouting.

Grouting and caulking

1. Mix the grout. Mix to a peanut-butter consistency, let it slake (rest) for the time on the bag, then remix briefly. Mix only what you can use in about 20 to 30 minutes.
2. Pack the joints. Hold the rubber float at about 45 degrees and push grout diagonally across the joints so it fills them completely. Skip the joint where the tile meets the counter and the inside corners; those get caulk.
3. Clean in stages. After 15 to 30 minutes, when the grout is firm, wipe diagonally with a damp (not dripping) sponge, rinsing often. Too much water weakens grout and lightens the color. Buff off the haze with a dry microfiber cloth after it dries.
4. Caulk the change of plane. Run a bead of color-matched silicone or siliconized caulk where the tile meets the counter and in any inside corners. These joints move with the house, and grout there cracks. Tape both sides of the joint for a crisp line, tool it smooth and pull the tape while the caulk is wet.
5. Reinstall devices. Once everything is dry, reinstall outlets and switches on the extenders, add cover plates, and turn the breakers back on. Test every outlet, especially GFCI outlets, which are required near kitchen sinks and counters.
6. Seal if needed. Cement grout benefits from a penetrating sealer after it cures, usually 48 to 72 hours. Check the grout bag; some modern grouts don’t need it.

Mistakes to avoid

• Starting in a corner. Starting in the corner almost guarantees a skinny, awkward cut at the most visible spot. Lay out from the center.
• Trusting the counter. A ledger board fixes an out-of-level counter. Following the counter carries the error all the way up.
• Skipping box extenders. Recessed outlets with tile around them are a code and safety problem, and the devices won’t sit right.
• Grouting the counter joint. It will crack within months. Caulk it.
• Spreading too much adhesive. Mastic and thinset skin over. If it no longer sticks to your finger, scrape it off and spread fresh.

When to call a pro

A backsplash is a good DIY job on a flat, sound wall. Call a contractor if the drywall behind it is water-damaged or soft, if you need outlets moved or added (that is electrical work), if you’re working with natural stone, large-format or glass tile that is less forgiving, or if the backsplash is part of a bigger kitchen update with new counters. Counters should go in before the backsplash, so it often makes sense to plan both together. Our kitchens and baths team handles everything from tile to full remodels, and we can fold drywall repairs into broader interior remodeling work.

Rather have it done for you? RossBuilt Construction serves the St. Louis metro. Request a free estimate or call 636-380-2574.