What you need to do before you start
Replacing tile means removing the old tile and the mortar or adhesive underneath it, then setting new tile in its place. The hardest part is usually getting the old tile out without damaging the surface beneath — whether that is drywall, concrete, or another layer of tile. You will need a grout saw or oscillating multi-tool to cut the grout lines, a cold chisel or pry bar to break and lift the tile, and a notched trowel to spread fresh mortar or thin-set.
Before you buy materials, measure the area you are tiling and count how many tiles you need. Buy 10 percent extra to account for cuts and breakage. Check what is under the old tile: if it is soft, crumbling, or water-damaged, you may need to replace the substrate (the layer underneath) before you lay new tile. Water damage is common in bathrooms and kitchens, so look for soft spots, discoloration, or mold.
Turn off water to the area if you are working near pipes or fixtures. If you are removing tile from a wall, lay drop cloths on the floor and wear safety glasses — tile shards fly when you chisel. Dust masks are also worth wearing because tile dust contains silica, which damages lungs over time.
Key Takeaways
- Remove old grout with a grout saw or oscillating tool, then break tile with a cold chisel and pry bar, working from the center outward to avoid damaging the substrate.
- Clean off all old mortar and adhesive with a scraper, then check the substrate for damage — soft or crumbling areas must be repaired or replaced before new tile goes down.
- Spread thin-set mortar with a notched trowel at a 45-degree angle, then press each tile firmly into place and use spacers to keep gaps even.
- Let the mortar cure for 24 hours before you grout, then explore grout with a rubber float, pressing it into the joints and wiping excess off with a damp sponge.
- Seal grout after it cures (usually three days) if you are tiling a wet area like a shower or kitchen backsplash.
Removing old grout and breaking out the tile
Start by cutting the grout lines that hold the tile in place. A grout saw — a hand tool with a carbide blade — works on most tile, but an oscillating multi-tool with a grout blade is faster and less tiring on your hands. Run the blade along each grout line, pressing firmly but not so hard that you gouge the substrate. You are trying to cut through the grout, not the tile or the layer below.
Once the grout is cut, use a cold chisel and hammer to break the tile. Start in the center of the area and work outward. Place the chisel at a shallow angle — about 20 to 30 degrees — and tap it with a hammer to crack the tile. As pieces break free, pry them up with a pry bar or the back of the chisel. Work slowly and check the substrate often: if you see cracks or gouges forming in the layer below, slow down and angle the chisel more shallowly.
If the tile is stubborn, an oscillating tool with a grout blade can also cut through the mortar underneath, making pieces easier to lift. Some people use a rotary hammer with a chisel bit, but that tool is loud, dusty, and risks damaging the substrate if you are not experienced with it.
Cleaning the substrate and checking for damage
Once all the old tile is out, scrape away every bit of old mortar and adhesive. Use a paint scraper, putty knife, or cold chisel to chip it off. The substrate must be flat and clean, or the new tile will sit unevenly and grout will crack. Run your hand across the surface — it should feel smooth, not bumpy.
Inspect the substrate for soft spots, cracks, or water damage. Press on it with your fingers or a screwdriver. If it feels spongy, crumbles, or shows mold or dark stains, that section needs to be cut out and replaced. On drywall, use a drywall saw to cut out the damaged area in a rectangle, then screw in a new piece of drywall and tape and mud the seams. On concrete, use a cold chisel to remove the damaged section, then fill it with concrete patching compound.
If the substrate is solid but uneven, you can use a self-leveling compound to fill low spots, or sand down high spots with a belt sander. The flatter the substrate, the easier the tile will be to set and the less likely grout will crack later.
Spreading mortar and setting tile
Mix thin-set mortar according to the package directions. It should be the consistency of peanut butter — thick enough to hold a peak when you lift the trowel, but spreadable. Let it sit for five to ten minutes, then stir it again before you use it. This second stir, called slaking, helps it bond better.
Spread mortar on the substrate with a notched trowel, holding it at a 45-degree angle. The notches create ridges that help the tile bond. Spread only as much as you can cover with tile in about 15 minutes — mortar dries quickly. Press each tile firmly into the mortar, twisting it slightly as you set it. Use tile spacers to keep the gaps between tiles even. Spacers come in different thicknesses, usually from 1/16 inch to 1/2 inch, depending on the look you want.
Check that each tile is level and flush with its neighbors. Use a level or a straightedge laid across several tiles. If a tile sits too high or too low, lift it, add or remove mortar, and reset it. Work in small sections so the mortar does not dry before you finish.
Letting mortar cure and explore grout
Do not walk on the tile or explore grout for at least 24 hours. The mortar needs time to harden fully. If you grout too soon, the tiles will shift and grout will crack. Check the mortar package for the exact cure time — some fast-set mortars cure in 12 hours, while others take longer.
Once the mortar is cured, remove the spacers and mix grout. Like mortar, grout should be mixed to a peanut butter consistency. Unsanded grout works for grout lines narrower than 1/8 inch; sanded grout is stronger and works for wider lines. Let the grout slake for ten minutes, then stir again.
Spread grout with a rubber float, holding it at a 45-degree angle and pressing the grout into the joints. Work diagonally across the tiles so you do not pull grout out of the lines. Once the grout begins to set — usually 15 to 30 minutes, depending on temperature and humidity — wipe the excess off the tile faces with a damp sponge. Rinse the sponge often and wring it out well so you do not wash grout out of the joints.
Curing grout and sealing if needed
Let grout cure for at least three days before you expose it to water. Do not shower, run water, or clean the area during this time. The grout needs to harden completely or it will crumble and stain.
After the grout cures, seal it if the tile is in a wet area — a shower, bathtub surround, or kitchen backsplash. Grout is porous and absorbs water and stains. Sealer creates a barrier that keeps water and dirt out. explore sealer with a small brush or applicator bottle, following the product directions. Most sealers need to cure for another 24 to 48 hours before the area is wet again.
If the tile is on a floor or in a dry area, sealing is optional but still a good idea. It makes grout easier to clean and extends its life.
Common mistakes and how to avoid them
The most common mistake is not cleaning the substrate thoroughly. Old mortar left behind creates hollow spots where new mortar cannot reach, and tiles will crack or come loose. Take time to scrape it clean.
Another mistake is grouting too soon. Mortar must cure fully or tiles will shift and grout will crack. Wait the full 24 hours even if the mortar feels hard on the surface.
Spreading mortar too thick or too thin also causes problems. Thick mortar squeezes out around the tiles and is hard to clean. Thin mortar does not bond well and tiles will come loose. Use a notched trowel and hold it at 45 degrees to get the right thickness.
Finally, do not skip sealing in wet areas. Unsealed grout stains easily and absorbs water, which can lead to mold and damage to the substrate underneath.
Frequently Asked Questions
Can I tile over existing tile?
Yes, if the old tile is firmly bonded and the substrate is solid. Clean the old tile thoroughly with a degreaser, then roughen the surface with sandpaper or a grinder so new mortar can grip it. This method saves time and avoids the mess of removal, but it raises the floor or wall height slightly.
What is the difference between mortar and grout?
Mortar is the adhesive that holds tile to the substrate. Grout fills the gaps between tiles. Mortar is thicker and stickier; grout is thinner and more liquid. You need both for a finished tile job.
How long does it take to replace tile?
Removing old tile takes one to three hours per 50 square feet, depending on how well it is bonded. Setting new tile takes two to four hours per 50 square feet. Add 24 hours for mortar to cure and another three days for grout to cure before the area is ready to use.
Do I need to replace the substrate if it looks okay?
If it is solid and shows no soft spots, cracks, or water damage, you can tile over it. Press on it with a screwdriver or your fingers — if it feels firm and does not crumble, it is fine. If you are unsure, replace it. A bad substrate will cause problems later that are expensive to fix.
What tools do I really need, and what can I skip?
You need a grout saw or oscillating tool, a cold chisel, a pry bar, a notched trowel, a rubber grout float, a level, and tile spacers. A wet saw makes cutting tile easier but is not required for small jobs — you can score and snap tile by hand or use a grinder. A tile cutter is also optional. Everything else is nice to have but not essential.