How to Install Slate Backsplash

Installing a slate backsplash can add beautiful visual interest and dimension to your kitchen or bathroom. Slate is a natural stone that comes in a range of colors and textures, making it a versatile design choice. With some planning and proper installation techniques, you can have a stunning slate backsplash in your home.

Choose the Right Slate

There are a few key considerations when selecting slate for your backsplash:


Slate comes in cleft, honed, and tumbled varieties. Cleft has a natural, split texture. Honed is smooth with soft edges. Tumbled slate has rounded edges and an antiqued look. Consider which finish best suits your design vision.


Slate backsplashes come in various natural shades of gray, black, purple, green, and blue. Pick a color that complements your cabinetry, countertops, and overall decor. Be sure to view slate samples in person before making a final decision.


Standard slate backsplash tile thickness is 1/4 to 3/8 inches. Thicker slate panels (1/2 inch or more) create a dramatic ledgestone look. Thinner pieces are better for a smooth, seamless look.


Common slate backsplash sizes range from small mosaics to large-format 12×24 inch rectangles. Mosaics create fluid patterns while large tiles minimize grout lines. Choose a size that aligns with your design goals.

Gather Supplies

Slate tile and backerboard are the main components, but you’ll also need:

  • Tile mortar and grout
  • Notched trowel
  • Mixing bucket
  • Grout float
  • Grout sealer
  • Tile spacers
  • Tile cutter
  • Safety gear

Shop for high-quality slate and backerboard made for wet areas. Use waterproof mortar and grout. Have tile tools on hand before starting.

Prepare the Surface

Proper prep is crucial for a long-lasting slate backsplash installation:

  • Remove existing backsplash if there is one
  • Inspect walls for damage and repair as needed
  • Clean surface thoroughly and seal if painting
  • Install cement backerboard per manufacturer instructions
  • Let backerboard dry completely

Take time to start with a smooth, even, and well-supported surface. Backerboard gives structure and prevents moisture damage.

Plan Your Layout

A thoughtful slate layout ensures an eye-catching backsplash design. Here’s how to plan:

  • Measure the backsplash area and sketch your slate tile layout
  • Dry lay tiles on the counter to visualize placement
  • Cut border and accent tiles as needed
  • Mix tile pieces for color variation
  • Determine grout line width based on slate size

Having a tile map keeps the installation organized and helps you cut tiles ahead of time.

Install the Tiles

Now it’s time for the fun part – setting the slate! Follow these best practices:

1. Prepare the mortar

Mix mortar per package directions. Let it slake for 10 minutes before using.

2. Apply the mortar

Use the notched side of the trowel to spread a thin, even layer of mortar onto the backerboard.

3. Set the tiles

Press tiles into the mortar, using spacers for consistent grout lines. Push out air pockets.

4. Check alignment

Verify tiles are level and aligned as desired as you go. Adjust as needed.

5. Cut edge pieces

Use the tile cutter to trim tiles to fit around outlets, edges, etc.

6. Let mortar cure

Allow mortar to fully cure (at least 24 hours) before grouting. Remove spacers.

Take care to keep slate clean during installation. Work in sections for easier mortar application.

Apply the Grout

Grout fills the joints between slate tiles. Follow grouting best practices:

  • Choose unsanded grout for slate with tight joints
  • Apply grout by pressing into joints with the grout float
  • Wipe diagonally across tiles with a damp sponge
  • Clean haze off tile faces with a soft cloth
  • Wait 72 hours and apply grout sealer

Match your grout color to the slate for a subtle look. Contrasting grout highlights the tile layout.

Care for Your Slate

Slate backsplashes are durable, but proper care is recommended:

  • Seal slate annually to prevent staining
  • Use pH-neutral cleaner for regular cleaning
  • Re-apply grout sealer every 2-3 years
  • Avoid harsh cleaners and scrubbing
  • Immediately clean up spills to prevent stains

Treating your slate backsplash with care helps maintain its beauty for years to come.

Frequently Asked Questions

What kind of slate is best for backsplash?

For backsplashes, cleft or honed slate with a thickness of 1/4 to 3/8 inches offers durability and visual appeal. Stay away from soft, flaky varieties.

Does slate need to be sealed?

Yes, sealing is highly recommended to prevent staining and water damage over time. Use a penetrating sealer made for natural stone. Reapply yearly.

How do you cut slate tile?

Use a wet tile saw or snap tile cutter to cut slate. For intricate cuts, use a mini grinder with a diamond blade. Always wear safety goggles.

Can you use regular grout on slate?

Slate needs unsanded grout for the joints. Sanded grout can scratch the slate surface. Make sure to use grout specifically formulated for natural stone.

How long does slate tile installation take?

Allow 2-3 days for a typical slate backsplash installation. The mortar drying time takes up most of this period. Plan accordingly when scheduling the project.


With proper planning and installation techniques, a stunning slate backsplash can be achieved in your home. Carefully choose your slate, prepare the surface, layout the design, set the tiles, grout, and maintain the slate. Paying attention to details results in a cohesive backsplash that will bring you joy for years to come. A slate backsplash adds natural beauty, dimension, and sophistication wherever it’s installed.