How to Fix Grout That Is Cracking (Before It Gets Worse)

Cracking grout is one of the most common tile floor problems — and one of the most important to fix quickly. Once grout cracks, water can seep underneath the tiles, weakening the adhesive bond and eventually causing tiles to loosen, lift, or crack themselves.

The good news: fixing cracked grout is a straightforward DIY repair that takes just a few hours and doesn't require any special skills.

Why Does Grout Crack?

• Subfloor movement — the most common cause; if the subfloor flexes, the grout cracks
• Insufficient grout joints — grout lines that are too narrow don't allow for natural tile expansion
• Wrong grout type — using wall grout on floors, or unsanded grout in wide joints
• Grout applied too thin — shallow grout joints crack faster under foot traffic
• Age and wear — grout naturally becomes brittle over time, especially in high-traffic areas
• Settling — new construction settling can stress grout joints

What You'll Need

• Caulking & Grout Removal Tool — to remove cracked grout cleanly
• Pre-Mixed Tile Grout — for refilling the joints
• Grout float or putty knife
• Damp sponge or cloth
• Vacuum or brush

How to Fix Cracking Grout: Step-by-Step

Step 1: Remove all cracked grout.
Don't just apply new grout over cracked grout — it won't bond properly and will crack again quickly. Use a grout removal tool to rake out all the cracked and loose grout from the affected joints. Go at least 2–3mm deep to give the new grout a solid base to bond to.

Step 2: Clean the joints thoroughly.
Vacuum out all dust and debris from the open joints. Wipe with a damp cloth and allow to dry completely. Any moisture or dust left in the joint will prevent the new grout from bonding.

Step 3: Apply new grout.
Open your pre-mixed tile grout and press it firmly into the cleaned joints using a grout float or putty knife. Work at a 45-degree angle to pack the grout fully into the joint with no air pockets.

Step 4: Wipe away excess.
Before the grout sets, wipe away excess from the tile surface with a damp sponge. Rinse the sponge frequently and work in circular motions to avoid pulling grout out of the joints.

Step 5: Allow to cure.
Let the grout cure according to the product instructions — typically 24–48 hours before light foot traffic, and 72 hours before getting it wet.

Step 6: Seal the grout (recommended).
Once fully cured, apply a grout sealer to protect the new grout from moisture, staining, and future cracking. This step significantly extends the life of your repair.

When Cracking Grout Is a Sign of a Bigger Problem

If grout cracks keep coming back in the same spots, the issue is likely subfloor movement rather than the grout itself. Signs of a deeper problem include:

• Grout cracking in a consistent line or pattern across the floor
• Tiles that feel springy or hollow when you walk on them
• Cracks appearing within weeks of a repair

In these cases, the subfloor needs to be reinforced or the tiles need to be re-laid over a more stable base before the grout repair will hold.

Frequently Asked Questions

Can I apply new grout over cracked grout?
No — new grout applied over cracked grout won't bond properly and will crack again quickly. Always remove the damaged grout first before applying fresh grout.

What's the best grout for floors that crack a lot?
Epoxy grout is significantly more flexible and crack-resistant than standard cement grout. It's a good choice for floors with minor subfloor movement or high-traffic areas.

How long does grout repair last?
A properly done grout repair on a stable subfloor can last many years. Sealing the grout after repair significantly extends its lifespan.

Should I use caulk instead of grout in corners?
Yes — corners and transitions between floor and wall should always be filled with flexible caulk rather than grout. Grout in corners will always crack because these areas experience the most movement.