How to Grout Rough Tile Backsplash

Installing a tile backsplash can add visual interest and dimension to your kitchen or bathroom. However, working with rough, uneven tiles can present some challenges when it comes time to grout. Proper preparation and technique are key to getting a smooth, consistent grout finish on rough backsplash tiles.

What You Need to Grout a Rough Tile Backsplash

Before starting to grout, ensure you have all the necessary supplies:

  • Grout – Either sanded or unsanded, depending on the spacing between your tiles
  • Grout float – For spreading and pressing grout into joints
  • Grout sponge – For wiping away excess grout
  • Bucket or basin – For grout mixing
  • Grout sealer – To protect grout pores after installation
  • Clean water – For cleaning and rinsing
  • Old rags & paper towels – For wiping away excess grout

Optional items:

  • Grout bag – For applying grout into narrow joints
  • Grout lines – Helps guide straight grout lines
  • Grout saw – For removing old or hardened grout

Preparing Rough Tile for Grouting

Proper prep before grouting is crucial for getting grout into all the nooks and crannies of rough tile. Here are some tips:

Clean tiles thoroughly – Use a stiff nylon brush and grout cleaner to remove all dirt, debris and dust from the cracks and crevices of the rough tiles and joints. Rinse thoroughly.

Widen joints if needed – For wide grout joints, you may need to widen them with a grout saw to allow the grout to fully fill the space.

Dampen tiles lightly – Using a sponge, wipe a light coat of clean water over the entire surface just before applying grout. This helps prevent premature drying.

Work in small sections – Don’t grout a large area all at once. Work in 3-4 square foot sections for best results.

Mixing and Applying Grout for Rough Tile

Follow these tips for hassle-free grout application:

Mix to a thick consistency – Mix grout just to the consistency of a thick toothpaste, not too watery or soupy. This allows it to stick well and fill joints.

Force grout into joints – Use the grout float to forcibly press and compact the grout into every crevice and joint. Apply at a 45° angle and work diagonally across joints.

Pack tightly – Keep packing in grout until joints are completely filled flush with the tile surface.

Remove excess – Holding float at a 90° angle, scrape off any excess grout sitting on the tile surface.

Don’t let it dry – As you work, continually dampen completed sections with a sponge to prevent drying before wiping.

Wipe diagonally – Once grout in joints has firmed up slightly, wipe diagonally across tiles with a damp sponge to level and smooth joints. Rinse sponge frequently.

Check for voids – Carefully inspect for unfilled voids after wiping. Re-pack any voids and wipe again.

Final wipe – Once grout in joints becomes firm, do a final wipe with a clean, damp sponge to clean any remaining grout residue from the tile surface.

Allow to fully cure – Let grout dry completely according to manufacturer directions before using shower/tub.

Tips for Grouting Rough Tile Backsplash

Follow these tips for the best grouting results on uneven tile:

  • Use sanded grout for joints wider than 1/8 inch to avoid cracking.
  • Ensure grout joints are a consistent depth for a uniform appearance after wiping.
  • Alternate direction of grout floats as you work to fully pack joints. Grout across joints, then diagonally.
  • Expect to use more grout than a smooth tile backsplash. Rough tile has more surface area to fill.
  • Take extra time working the grout into the rough spots and crevices for proper adhesion.
  • Check for unfilled spots after initial wipe down. Be prepared to do additional packing and wiping.
  • Don’t rush to wipe down grout. Allow time for it to firm up in joints before wiping.
  • After final wipe, go back and check for haze. Wipe again if needed before it completely dries.
  • Cure grout fully before exposure to water to prevent premature cracking or deterioration.

Grouting rough backsplash tile requires patience and attention to detail. But taking the time to properly force grout into all the uneven nooks and crannies will help ensure your finished product looks flawless. With the right techniques, you can achieve a smooth grouted finish on even the roughest tile surfaces.

Frequently Asked Questions About Grouting Rough Tile Backsplashes

How long should I wait before wiping down grout on rough tile?

Wait 30-45 minutes before doing the initial wipe down on rough tile. This allows the grout to firm up in the joints so it doesn’t pull out too much. Check for dryness and do a test wipe on a small area first.

What’s the easiest way to get grout into the rough spots?

Using a grout bag is the easiest way to fill rough crevices. Simply squeeze grout directly into any hard-to-reach joints or holes in the tile. You can also use a small artists paintbrush to work grout into rough spots.

Do I need to seal my grout after installing on rough tile?

Yes, it’s highly recommended. The porous, uneven surface of rough tile means grout is more susceptible to staining and discoloration. A penetrating grout sealer provides an added layer of protection.

Can I use premixed grout on rough backsplash tiles?

This isn’t recommended. Premixed grout lacks the abrasive polymers in sanded grout that help it adhere properly. Sanded grout is a much better choice for rough or uneven tile.

How soon can I get my rough tile backsplash wet after grouting?

It’s best to wait the full cure time specified on your grout before exposure to water. This is usually 72 hours. This allows grout to fully hydrate and gain its maximum hardness to resist cracking or washing out of joints.


Grouting a rough or uneven tile backsplash adds an extra challenge versus smooth tile. However, with diligent joint cleaning, proper mixing and application of grout, and taking care to tightly pack grout into every crevice, you can achieve a flawlessly smooth grouted finish. Allowing plenty of drying and cure time is also key for durable grout joints that won’t crack or deteriorate prematurely when exposed to moisture. With some extra care and effort, a professionally grouted rough tile backsplash can bring stunning visual interest and dimension to your space.