How to Fill Gap Between Backsplash and Wall

Filling the gap between your backsplash and wall is an important finishing touch when installing a backsplash. That space where the backsplash meets the wall, if left unfilled, can collect dirt and debris. Filling it properly not only looks better, but helps keep your backsplash clean. There are several good options for filling that gap, whether you want a simple solution or something more decorative. Follow these tips for a seamless transition between backsplash and wall.

Materials Needed to Fill Backsplash Gap

Filling in the gap between backsplash and wall doesn’t require many materials. Most of what you need may already be on hand. Here is a list of the basic materials:

  • Caulk or silicone sealant – Acrylic or silicone caulks work well. Match the color to your grout or backsplash.
  • Painter’s tape – Used to keep caulk neat and straight. Removed after caulk dries.
  • Grout – Can be used to fill larger gaps. Match the color to your existing grout.
  • Scrap piece of backsplash tile – Cut into strips and used to fill large gaps.
  • Sponge – For smoothing caulk and cleaning up excess.
  • Mixing stick or dowel – For mixing grout and pressing it into gaps.
  • Grout sealing product – Used after installing grout to fill gaps.

Make sure to have a clean workspace and all your materials on hand before beginning. Check that the gap is free of loose debris. Now let’s look at the steps for how to fill in that pesky backsplash gap.

Step 1: Prepare the Gap Between Backsplash and Wall

Before applying any filler material, you need to properly prepare the gap. Here’s how:

  • Make sure the gap is clean and free of dust or particles. Wipe it out with a dry cloth.
  • If the gap is very uneven, you can use a utility knife to straighten and smooth it out.
  • Use painter’s tape on the wall above the backsplash. This will help keep caulk neat and provide crisp lines.
  • Be sure the backsplash and wall are dry before applying caulk or grout.

Preparing the gap takes a bit of work upfront, but helps ensure a lasting fill.

Step 2: Apply Caulk to Small/Average Backsplash Gaps

For small to average size gaps between the backsplash and wall, caulking is an easy solution. Here’s how to apply caulk:

  • Load caulk into a caulk gun if it’s in a tube. Cut the tip at a 45° angle for better flow.
  • Run a neat caulk bead along the gap between wall and backsplash. Don’t skimp on the caulk.
  • Use a caulk tool, old gift card or your finger to smooth out the caulk and press it into the gap. Remove any excess.
  • Spray caulk lightly with water or rubbing alcohol to help smooth the finish.
  • Remove painter’s tape after caulk dries, about 30 minutes.
  • Cured caulk should be smoothed out evenly with the backsplash and wall.

Let the caulk dry fully before getting the backsplash wet or applying any pressure. Silicone caulk requires about 24 hours to cure.

Step 3: Use Grout for Large Backsplash Gaps

For large gaps of 1/8 inch or bigger, grout is a better choice than caulk. Here’s how to grout backsplash gaps:

  • Mix up grout in a small container using a grout float or mixing stick. Match grout color to your existing grout.
  • Press the mixed grout firmly into the gap using a spatula, dowel or your fingers. Overfill slightly.
  • Allow the grout to become firm, then smooth it out so it’s level with the existing grout. Remove excess.
  • Allow grout to dry completely, about 24 hours.
  • Seal grout so it’s waterproof using a grout sealer. Apply sealer with a small foam brush.

The benefit of grout over caulk is it will last longer in wider gaps. It also gives a uniform look if your existing grout lines are wide.

Step 4: Use Backsplash Scraps for Wide Gaps

For very wide gaps wider than 1/8 inch, you can fill them using cut pieces of backsplash tile. This creates a continuous look.

  • Cut your extra tile into strips or small pieces with a wet saw or tile cutter.
  • Dry fit the tile pieces in the gap to ensure a good fit.
  • Mix a tile adhesive that matches your original adhesive and apply it liberally to the back of the tile scraps.
  • Press tiles into the gap, using painter’s tape to hold in place until adhesive cures, about 24 hours.
  • Once adhesive has cured, mix grout and apply over top of the tile strips, smoothing flush with wall.

Using tile pieces takes more time but provides a seamless fill for wide backsplash gaps, leaving no cracks or caulk lines.

Step 5: Finish and Seal the Newly Filled Gap

Once your gap is filled with caulk, grout or tile, there are a few finishing steps to complete:

  • If haze or excess filler material remains on the backsplash tiles, clean it off with a soft, damp sponge.
  • Seal grout or caulk with an appropriate sealer so it is protected from moisture.
  • If rough edges remain, carefully smooth with a utility knife or fine grit sandpaper.
  • Examine gap from different angles to ensure it looks even and consistent.

Taking time to properly finish and seal your newly filled gap will keep it looking great and prevent debris buildup.

Tips for Keeping the Backsplash Gap Filled

To increase the longevity of your gap fill solution, keep these tips in mind:

  • When cleaning your backsplash, use mild soap and water only. Avoid harsh cleaners or chemicals on caulk or grout.
  • Reapply grout sealer every 1-2 years as needed to protect from moisture damage.
  • If gaps wider than 1/8 inch develop over time, don’t keep caulking over them. Remove caulk and refill with grout or tile scraps.
  • Watch for cracks in caulk or grout. Fill small cracks with fresh sealant before they spread.
  • Use mold resistant caulk or grout in high humidity areas like behind sinks or stoves.

With proper installation and care, your filled backsplash gap should hold up beautifully for years before needing redone.

Frequently Asked Questions About Filling Backsplash Gaps

Here are answers to some of the most common questions about properly filling the gap between backsplash and wall:

Should I use caulk or grout to fill the gap?

Use caulk for small, average gaps less than 1/8 inch wide. For larger gaps 1/8 inch or wider, grout will last longer.

What color caulk or grout should I use?

Match the color to your existing grout lines for a seamless look. Use white or clear caulk forwhite grout. Use sanded grout colors like almond or smoke for larger grout gaps.

How long does caulk or grout in the backsplash gap last?

With proper sealing, caulk should last 1-5 years before needing replaced. Grout can last 5-10 years or longer before crumbling or cracking.

Should I use silicone or acrylic caulk to fill the gap?

100% silicone caulk adheres well, resists moisture, and lasts longer than acrylic. Acrylic caulk is cheaper but doesn’t hold up as long.

Can I use the same caulk on the countertop and backsplash?

Yes, use matching caulk between countertop and backsplash and where the backsplash meets the wall for visual consistency.

What’s the easiest way to get a clean caulk line?

Painter’s tape helps create nice straight caulk lines. Tool the caulk with your finger or a caulk shaping tool before it dries.

Why does my caulk crack after a few months?

Cracking can be caused by using too little caulk, not sealing properly, or bathroom moisture affecting adhesion.

How can I remove old caulk or grout before reapplying?

Use a razor blade, utility knife, or caulk removal tool to carefully scrape out old caulk. For grout, a grout removal bit attached to a rotary tool works well.


Filling the gap between your new backsplash and the wall is an essential finishing step for a quality installation. Taking time to properly prep the gap, apply caulk or grout, and smooth out the finish will leave your backsplash looking seamless. Caulking small gaps and using grout or tile in wider gaps will provide long lasting results.

Maintaining filled gaps by resealing grout and watching for new cracks will prevent moisture damage and debris buildup. A neatly filled backsplash gap helps showcase your beautiful new backsplash and keeps the space looking finished.