How to Grout Uneven Tile Backsplash

Grouting a tile backsplash can seem intimidating, especially if the tiles are uneven or the grout lines are wide. But with some planning and the right techniques, you can achieve a smooth, uniform grout finish. Here is a step-by-step guide on how to grout an uneven tile backsplash.

Prepare the Tile Surface

Before grouting, make sure the tile surface is clean and free of dust, grease, or sealants. Use a damp sponge to wipe down the tiles. This will help the grout adhere properly.

Check for uneven tiles and wide grout lines. If there are tiles that stick out further than others, you may need to use grout spacers or push the tiles in to even the surface. Wider grout lines will require more grout.

Choose the Right Grout

For an uneven tile backsplash, a high quality, polymer-modified sanded grout is best. The sand in the grout provides texture to fill wide grout lines and uneven spaces between tiles. A polymer additive makes the grout more flexible and resistant to cracking.

Make sure to choose a grout color that matches or complements your tile. Apply a grout release or sealer if recommended for the tile type.

Mix and Apply Grout

Mix the grout per package directions. The consistency should be thick but still spreadable. Apply grout by holding the float at a 45° angle and forcing it into the grout lines and spaces between tiles.

Spread the grout diagonally across the tiles to fill all voids evenly. Take care to fully pack wider grout lines. Go over the entire surface multiple times to ensure thorough, even coverage.

Clean Excess Grout

Let the grout sit for about 15 minutes until it becomes firm. Use a damp sponge to wipe diagonally across tiles and smooth grout lines. Rinse the sponge frequently to remove excess grout.

Avoid wiping in a circular motion as this can pull grout out of joints. Continue cleaning until all residue is gone from the tile surface.

Final Touch Up

Inspect for any low spots or uneven grout lines. Use the edge of the float or a shaping tool to smooth and shape grout. Repair pinholes or cracks with extra grout.

Wipe down the tiles one final time with a damp sponge. Allow the grout to dry completely, typically 24-48 hours. Apply a grout sealer if desired for added protection.

Tips for Grouting Uneven Tiles

Grouting uneven tile backsplash can be tricky. Here are some tips to help it go smoothly:

Use a Grout Bag

A grout bag lets you apply grout in a controlled way. Squeeze it into gaps and voids between uneven tiles for a consistent fill. This takes practice but prevents over-grouting.

Apply Grout in Sections

Rather than grouting the entire backsplash at once, work in smaller sections. This allows you to focus on leveling and cleaning one area before moving to the next.

Check Grout Lines with a Straightedge

Use a level or straight piece of wood to check for even grout lines after applying grout. Look for low spots to touch up.

Grout From the Bottom Up

When grouting a vertically uneven area, start from the bottom and work upwards. Gravity will help fill in gaps and voids.

Let Grout Firm Up Slightly

Don’t wipe down tiles immediately after applying grout. Let it set up for 10-15 minutes so it is firm enough to withstand cleaning.

Common Grout Issues on Uneven Tiles

Grouting uneven tiles comes with some potential pitfalls. Being aware of these common issues can help you avoid them:

Inconsistent Grout Lines

When tiles are misaligned, it causes uneven grout lines and thickness. Carefully checking lines and using a grout bag minimizes inconsistency.

Cracking and Crumbling Grout

Flexible grout with polymer additives is less likely to crack on uneven tiles. Crumbling grout is a sign of improper mixing or wiping too soon.

Grout Smears and Haze

Excess grout left on the tile surface can dry and cause a hazy appearance. Wipe tiles thoroughly before grout dries completely.

Low Spots and Gaps in Grout

Uneven tiles often have low spots with thin or no grout. Inspect closely and touch up low areas for complete fill.

Pinholes and Pockmarks

Air bubbles and pinholes in grout lines are common on uneven tiles. Carefully apply extra grout to fill and smooth marks.

Grout Pulling Out of Joints

When wiping tiles, using too much pressure or circular motions can pull grout out of grout lines. Wipe gently diagonally instead.

Frequently Asked Questions

How long should I wait to grout uneven tiles?

It’s best to wait 24-48 hours after installing uneven tiles to grout. This allows tile mortar to cure properly and prevents tiles from shifting during grouting.

Should I use sanded or unsanded grout?

For uneven tiles with wide grout lines, use a polymer-modified sanded grout. The sand provides texture to fill gaps and joints. Unsanded grout is only for grout lines 1/8 inch or less.

What is the easiest way to apply grout on uneven tiles?

Using a grout bag gives the most control for forcing grout into uneven joints and gaps between tiles. Squeeze the bag gently to fill all voids.

How do I get grout lines straight on uneven tiles?

Check lines with a straightedge tool and use the edge of a float to shape and smooth out uneven grout. Touch up low spots to maintain straight grout lines.

Can I use caulk instead of grout on uneven tiles?

Caulk is not a substitute for grout on a tile backsplash. It does not provide the same stability and will not achieve the same uniform finish as grout.


Grouting an uneven tile backsplash presents challenges but can be done with patience and the right techniques. The key steps are preparing the surface, choosing a flexible grout, forcing grout into uneven spaces, thorough cleaning, and finish smoothing. Pay close attention to fill all voids completely and keep grout lines straight. With careful application and clean up, you can achieve durable, uniform grout lines, even on uneven tiles.