How To Install Backsplash In Corners

A step-by-step guide for installing backsplash in corners

Installing a beautiful and functional backsplash that wraps around corners can seem daunting, but with careful planning, the right materials, and proper technique, it is very achievable as a DIY project. Proper corner installation is crucial for a seamless look and to prevent cracking or chipping over time. This comprehensive guide will walk you through all the key steps for a flawless corner backsplash installation.


A backsplash serves both decorative and practical purposes in a kitchen or bathroom. Tiled backsplashes prevent water damage and make cleanup easier by protecting the walls around sinks, stoves, and other fixtures. Extending the backsplash around inside corners provides an elegant, finished look while also safeguarding vulnerable corners from moisture damage.

However, the corners present unique challenges for backsplash installation. Tiles must be precisely cut to fit the angles. Proper corner treatment prevents cracking from wall movement. The detailed steps below will help you achieve beautiful, durable corner backsplashes that stand the test of time.

Gather the Right Supplies

Installing a corner backsplash requires careful measurements, specialty tools, and the right materials. Ensure you have the following supplies on hand before getting started:


  • Ceramic, porcelain, or natural stone tiles suitable for backsplash use. Check manufacturer specifications.
  • Enough tiles to cover the entire backsplash area, including extra tiles to account for corner cuts, waste, and future repairs.
  • Color-matching grout for a consistent look.


Additional Supplies

  • Backerboard cementboard or water-resistant drywall
  • Thin set mortar adhesive
  • Grout sealant
  • Painter’s tape
  • Drop cloths
  • denatured alcohol for cleaning
  • Sponges and buckets

Thorough planning and the right supplies will ensure your corner backsplash installation goes smoothly from start to finish.

Step 1: Prepare the Surface

Proper surface preparation is crucial for a long-lasting corner installation. The backsplash must be applied to a water-resistant and stable surface.

For drywall corners:

  • Ensure the corner drywall is in good condition, with no cracks, damage, or imperfections. Repair any flaws with drywall compound.
  • The walls should be primed before tiling. This helps the thinset mortar adhere properly.
  • Apply painter’s tape along the edges to protect the surrounding walls.

For cementboard corners:

  • Cut the cementboard precisely to size using a utility knife and straightedge.
  • Pre-drill holes every 8 inches across the panels. This prevents cracking.
  • Attach the boards with cementboard screws, keeping seams evenly spaced.
  • Tape the seams with fiberglass mesh tape and apply acrylic cementboard tape over the mesh.
  • Allow to fully dry overnight before tiling.

The surface must be clean and dust-free before applying thinset mortar. Wipe down with denatured alcohol just prior to installation.

Step 2: Dry Fit the Corner Tiles

Dry fitting, or temporarily arranging the tiles, is an important planning step. This allows you to ensure the tile layout and design align properly around the corners before attaching with mortar.

  • Hold the corner tiles in place, adjusting the angles as needed.
  • Use small tile spacer clips or playing cards to set consistent grout line widths.
  • Check that full tiles align well on each wall, with natural cut lines at the corners. Avoid awkward slivers of tiles.
  • Note the placement of any tiles that will need to be cut. Remove these and set aside.
  • Make minor adjustments until you have a uniform layout you are satisfied with.

Dry fitting the corner tiles helps reveal any potential problems or adjustments needed in the tile layout before permanently setting the tiles in mortar. Slight variations in wall angles can be accounted for at this stage.

Step 3: Cut the Corner Edge Tiles

The most precise corner backsplash results will be achieved by cutting the edge tiles for each side of the corner, rather than cutting full tiles. This allows you to maintain the original tile edges wherever possible.

Carefully measure and mark the tiles:

  • Place the tiles to be cut back into the dry fitted corner space.
  • Mark the precise angle needed on each tile with a pencil.
  • For inside corners, angle the pencil slightly towards the center point to account for the beveled edge.

Use a wet saw fitted with a diamond tile blade to cut the tiles:

  • Cut slowly and smoothly for an even edge.
  • For ceramic or porcelain, cut face up with water flowing.
  • For natural stone, cut face down.
  • File any rough edgessmooth with a stone rubbing block.

Test the cut tiles in place and recut as needed for a perfect corner fit.

Step 4: Mix and Apply Thinset Mortar

With the tiles dry fitted and cut, you are ready to attach them permanently using thinset mortar adhesive.

  • Choose an appropriate mortar for the tile type and application. White polymer fortified thinset is ideal for most backsplashes.
  • Mix the dry powder with water per manufacturer directions to a smooth, toothpaste-like consistency.
  • Let the mixture slake for 10 minutes, then remix before use.

Apply a thin layer of mortar using a trowel with notches sized for the tiles:

  • Apply only as much mortar as can be tiled over in 15-20 minutes.
  • Use the flat side of the trowel to key the mortar into the surface, then comb parallel ridges with the notched side.
  • On the corner edges, sweep thinset diagonally across the seam to prevent gaps when the tiles are pressed in.

Mortar coverage should be full and even, with no gaps, slides, or misses. Consistent application prevents hollow spots that can lead to cracks.

Step 5: Set the Tiles into the Mortar

With the thinset mortar freshly combed on the walls, carefully set the tiles into place:

  • Begin with the field tiles, using spacers for even grout line spacing of 1/16th to 1/8th inch.
  • Press tiles firmly into place in a slight back and forth twisting motion to collapse the mortar ridges.
  • Check corners and seams to ensure no gaps are left between tiles or at awkward angles.
  • Insert the pre-cut edge tiles last, adjusting as needed for a perfect corner fit. Remove excess mortar squeezed out of the corners.
  • Embed tiles fully without any lippage or uneven tile edges.
  • Work in small sections and periodically check for proper adhesion, mortar coverage, and level alignment.

Let the mortar cure fully for 24-48 hours before grouting according to manufacturer specifications. Keep the tiles protected and undisturbed as the thinset sets.

Step 6: Mix and Apply Grout

Grout fills the joints between tiles, sealing and finishing the installation. For corner backsplashes:

  • Choose a grout that matches the tile color well for a seamless look.
  • Mix the grout powder with water or an additive according to package directions. Let stand 10 minutes, then re-mix to a smooth consistency.
  • Apply grout by packing it firmly into the joints using a grout float. Hold the float at a 45 degree angle and work diagonally across tiles.
  • Ensure grout reaches fully into inside corners and around irregular edges. Reapply if needed.
  • Once applied, hold the float edge flush and scrape diagonally across tiles to remove excess.
  • After 10-15 minutes, use a damp grout spongein a circular motion to smooth and clean tiles. Rinse sponge frequently.
  • Allow grout to cure fully for 72 hours before sealing or using fixtures.

Good grouting technique prevents cracking and damage to corner joints over time.

Step 7: Seal and Finish the Corner

Sealing the grout and applying trim or caulk completes the corner backsplash installation:

  • Apply grout sealer according to manufacturer directions to protect from moisture and staining.
  • For a clean finish, run a bead of clear silicone caulk where the countertop meets the corner edge.
  • Decorative trim or bullnose tiles also help finish inside corners neatly.
  • Remove spacer clips once grout has cured.
  • Clean tiles with a soft, damp sponge and mild soap, rinsing thoroughly.

With proper planning, technique, and care, tile backsplashes can be beautifully integrated into inside corners for a polished, seamless look. Maintain your investment by resealing grout every 1-2 years.

Frequently Asked Questions About Installing Corner Backsplashes

1. How are outside corners treated for backsplashes?

On external corners, use a file or rubbing stone to bevel or round the corner edge very slightly. This helps prevent cracking from wall movement. Apply trim or bullnose tiles for a neat finish.

2. How do I account for uneven wall corners?

Use tapered tile spacers to compensate for small inconsistencies in wall angles. For more significant unevenness, build out one side with thinset to create a plumb corner.

3. What mistakes cause corner cracking?

Insufficient mortar coverage, hollow spaces, uneven tile surfaces, and poorly mixed or cured grout can all lead to cracked corner joints over time. Ensure full adhesion and proper drying times.

4. How should I cut mosaic sheets for corner installation?

Cut mosaic sheets with diamond shears one tile in from the corner. Then using a wet saw, cut individual edge tiles for a precise fit.

5. Is special corner trim needed for marble tiles?

Yes, use specialty external or internal marble corner trims. This prevents chipping the fragile edges of natural stone tiles.

A stunning backsplash that flows seamlessly around corners takes planning and finesse. Follow these tips for flawless corner installation results. With careful technique, your new backsplash will be a durable and beautiful focal point.


Installing a backsplash cleanly and securely inside corners gives a polished finish, while also offering needed protection from moisture and grime where walls meet at vulnerable joints. With the right corner treatment, your new backsplash will beautifully tie each wall surface together into one cohesive design.

The detailed process outlined above will set you up for success in planning and executing inside corner backsplashes. Precision cutting and angling of the tiles ensures a tight fit without awkward cracks or gaps. Proper thinset mortar coverage and grouting technique prevents adhesion failures and damage over time. And finishing with trim or caulk gives a clean look and enhanced waterproofing.

While turning corners adds complexity, with care and patience, DIYers can achieve professional-looking results. The difference between a mediocre and marvelous backsplash often comes down to the quality of the corners. By using the tips provided, you can install an inside corner backsplash that will remain resilient and enhance your kitchen or bath for years of enjoyment.