How to Install Backsplash Over Existing Tile: The Complete Guide

Installing a new backsplash over existing tile can completely transform the look of your kitchen or bathroom. But this project does require some special preparation and techniques to ensure the new tiles adhere properly and look seamless. Follow this comprehensive guide to learn everything you need to know about how to install backsplash over existing tile.

Assessing the Existing Tile

The first step is to carefully examine the existing tile you’ll be installing over. This will determine what type of subsurface preparation is needed.

Check for Cracks or Damage

Carefully inspect all the existing tiles and grout lines for any cracks, missing pieces, or damage. Any compromised areas need to be repaired and leveled before installing the new backsplash. Otherwise those weak spots could cause the new tiles to crack or come loose over time.

If there are just a few cracked or missing tiles, remove and replace those. Use a grout saw or oscillating tool to remove the damaged tile and scrape out all the old grout. Then apply new thinset mortar and install a replacement tile that matches the existing ones as closely as possible. Regrout the new tile to blend it in.

For more significant tile damage or large missing sections, you may need to remove all the tile in that area and resurface with cement backerboard before installing the new backsplash.

Look for Loose or Hollow Tiles

Tap gently on each tile and listen and feel for any hollow or loose tiles. Solidly adhered tiles will have a quiet, solid tapping sound. Hollow areas sound darker and echo.

Use a putty knife or screwdriver to check for loose tiles or grout lines. Carefully try to insert the tip underneath. Be very gentle so you don’t accidentally pry off solid tiles.

Any loose, hollow tiles must be removed and replaced before installing the new backsplash. Use a chisel, putty knife, or oscillating tool. Again scrape out all the old thinset and grout, then apply new mortar and reinstall replacement tiles.

Identify the Tile Type

Determine what type of tile is already installed. The most common existing tile materials are ceramic, porcelain, or natural stone. This affects what types of subsurface preparation and mortar are needed.

Ceramic tiles are most porous and prone to cracking, while porcelain is dense and non-porous. Natural stone varies depending on the type of rock. Granites are very hard while slates can flake.

Identifying glossy or textured finishes also helps select subsurface materials. Glossy tiles require maximum adhesion, while texturedStone may need added mortar to fill the surface pits and crevices.

Cleaning and Prepping the Surface

Once you’ve assessed the condition of the existing tiles, proper cleaning and prep work is crucial for proper adhesion.

Clean Off All Old Grout Haze

Use a grout haze remover cleaner or mix of vinegar and water to scrub off any remaining grout haze or film from the old tiles. Get into the grout lines and wipe down all tile surfaces.

Remove any existing caulk from countertop joints or edges. An old caulk bead can prevent the new backsplash from sitting flush to the counter.

Wash and Dry the Tiles

Wash the entire surface well after cleaning off the grout haze. Soap scum, grease, or dust needs to be removed for the new tiles to adhere.

Use clean water to rinse off any soap residue. Wipe the tiles down well with a clean towel to dry. Allow the surface to fully dry before moving to the next step.

Scuff Up Glossy Tiles

If the existing tiles have a shiny glazed finish, scuff them up to improve mortar adhesion. Use a carbide-grit scouring pad to lightly scratch the glazed surface.

Don’t grind deeply into the tile, just rough up the top gloss coat. Wipe away all the loose dust after scuffing.

Apply Bonding Primer

Use a bonding primer made for tile like Mapei Tile Primer before installing over existing tile. Roll on an even layer with a paint roller over the whole surface.

This chemically etches the slick tiles so the new thinset mortar can grip better. Allow the primer coat to fully dry per manufacturer instructions.

Applying the Mortar

With the surface prepped, it’s time to apply the mortar that will adhere the new backsplash tiles.

Select the Proper Mortar

The type of mortar required depends on the existing tile type and new tile. Consult the tile manufacturer’s instructions to determine the best option.

For ceramic, porcelain, or natural stone, a polymer-modified thinset is best. Latex additives make it more flexible and improve adhesion.

Epoxy mortar is another option for slick surfaces like porcelain or metal backsplashes. It resists water and heat better than regular thinset.

Apply Mortar with Proper Trowel

Load the trowel evenly across the teeth, then apply to the wall using full pressure. Apply only as much as can be tiled over in about 10-15 minutes before it starts to dry and skin over.

Use a 1/4” x 3/8” square- or u-notched trowel for ceramic tiles. Heavier stone tiles may require a larger 1/2″ notch trowel.

Be sure to comb full notched rows, do not swirl or overlap. Consistent straight rows ensure maximum coverage.

Back-Buttering Tiles

For a very secure bond, also apply a skim coat of mortar to the back of each tile before placing, known as back-buttering.

Use the flat side of the trowel to apply a thin uniform layer of mortar directly onto the backs of the tiles. This doubles the contact coverage.

Setting the New Tiles

Once the mortar is prepped, it’s time to set the new tiles into place.

Plan Layout

Dry lay the new tiles on a flat surface first to determine the optimal layout. Measure the area and tiles to calculate how the side and top edges will need to be cut and laid out.

Plan the starter row at the bottom first, then align everything off of that. Have all specialty trim tiles ready as well.

Apply Tiles in Small Sections

Begin with the bottom row of tiles first. Use spacers to leave even 1/16” grout lines between tiles. Press each tile firmly into the fresh mortar to flatten it out.

Work in smaller sections of 2-3 square feet at a time. Adhere tiles while the mortar is still tacky. Don’t spread out mortar too far ahead in one step.

Check Alignment Frequently

As you set tiles, place a level tool against them to check for straightness and alignment. Make alignment adjustments right away before the thinset fully cures.

Step back periodically and sight down the applied tiles to look for any high or low spots. Fix them immediately with added mortar.

Cut Edge and Specialty Pieces

Measure and cut any edge tiles to fit around countertops, corners, outlets, or switches using a wet saw. Grind off any sharpness on cut edges.

Set any specialty border or trim tiles at edges, transitions, or focal points. Mosaic sheets should be preassembled and then applied as sheets.

Grouting the Backsplash

Once all tiles are fully set, properly grouting the joints is critical to protect and seal the installation.

Let Mortar Fully Cure

Allow the thinset mortar to fully cure for at least 24-48 hours before grouting tiles. This prevents sagging or sliding of tiles as you grout.

Cured mortar in the joints should be dry to the touch before grouting. The tiles should be firmly solid on the wall.

Choose Right Grout for Application

For kitchen backsplashes, use either sanded grout or nonsanded epoxy grout. Standard nonsanded grout is too porous for moisture exposure.

Match grout color with your tiles for minimal contrast. Contrasting grout highlights any uneven joints.

Grout Small Sections

Work in small 2-3 square foot sections to grout. Use a hard rubber float to force grout down into the joints. Hold at a 45° angle and scrape diagonally across tiles.

Wipe off excess grout with a damp sponge. Rinse sponge frequently to prevent haze and film from building up on tiles.

Seal Grout

After grouting, let cure fully for 72 hours. Then apply grout sealer with a small foam brush to penetrate and seal the grout lines. This prevents staining and moisture damage.

Reapply grout sealer every 1-2 years for ongoing protection and easier cleaning.

Tips for Success

Follow these top tips to help ensure your new backsplash installed over existing tile comes out perfectly:

  • Test existing tiles first to find hollow or loose areas before installing.
  • Clean surfaces thoroughly and scuff shiny tiles for better adhesion.
  • Use latex-modified thinset mortar for flexibility and strength.
  • Apply mortar and set tiles in small sections before thinset skins over.
  • Plan specialty edges and transitions before tiling.
  • Use spacers for consistent grout lines and check alignment often.
  • Allow mortar to fully cure before grouting, at least 24-48 hours.
  • Seal grout with a waterproofing sealer after installation.
  • Make sure the new tiles match the scale and layout of the existing design.

Frequently Asked Questions

Still have some questions about installing backsplash over existing tiles? Here are answers to some of the most common questions:

Do I Have to Remove the Old Backsplash?

In most cases no, you can install right over existing tile if it’s in good condition with minimal cracks or damage. Be sure to prep properly.

What Type of Mortar is Best?

Use a latex-modified thinset mortar which is more flexible and bonds better than regular thinset. Epoxy is also a good option for slick surfaces.

How Long Should I Wait Before Grouting?

Allow thinset mortar to fully cure for 24-48 hours before applying grout. Grout earlier and the tiles may shift or sink as you grout.

Can I Use Regular Grout?

No, use only epoxy or sanded grout for kitchens. Standard nonsanded grout is too porous for moisture and will easily crack.

How Do I Cut Holes for Outlets?

Measure and mark the exact opening size and location. Use a rotary tool with a diamond blade to carefully cut the outline, then chip out the waste.

Should Tiles Extend Below Backsplash Area?

Yes, tiles should extend at least 4-6 inches below the countertop seam for proper support and adhesion.


Installing a new backsplash over existing tile can refresh the entire look of your kitchen or bath without requiring full tile removal. Just be sure to properly assess, prep, and prime the existing tile first. When applying the new tiles and grout, work in manageable sections and allow proper cure times. Follow the techniques in this guide combined with the manufacturer’s instructions, and your new backsplash makeover will turn out beautifully.