Why is my grout cracking or falling out?
Cracked grout usually means something moved or the grout was mixed or cured badly. In corners and along the tub it is usually a joint that should have been caulk. Cracks in the middle of a wall or floor can point to a flexing floor, missing movement joints or poor tile bonding. Tap the tiles: if they are solid, regrout or recaulk; if any sound hollow, stop.
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By Kasra Taheri, Founder, LoclisPublished
Researched and drafted with AI, then checked claim by claim against the sources listed below before it was published. Prices and rules change; the dates beside each source say when it was last checked.
Step by step
Read when to stop and call a pro, further down this page, before you start.
Step 1: Note where the grout is failing
Look at whether the cracks are in the corners and along the tub or shower base, or out in the middle of a wall or floor, because corners and perimeters call for caulk rather than grout.[1]
Step 2: Tap every tile near the damage
Rap tiles with a knuckle or the handle of a screwdriver and listen for a hollow sound; a tile that sounds hollow or rocks is loose and is not a grout problem.[2]
Step 3: Look for the water
Check for a leak, a damp wall or mold behind the failing joints, and fix plumbing leaks and other water problems as soon as possible.[3]
Step 4: Clean and dry the joints
Scrub mold off hard surfaces with detergent and water, and dry completely before any repair.[3]
Step 5: Replace corner and tub joints with caulk
Scrape out cracked grout along the corners and the tub or shower base and refill with a tile caulk or silicone sealant, not new grout.[1]
Step 6: Regrout the field joints
If tiles are solid and only the grout in the middle of the wall or floor has crumbled, rake it out, wearing a NIOSH N95 respirator (mask) as the data sheet recommends, and regrout, following the shower regrouting steps linked below.[1]
Step 7: Mix and cure the new grout correctly
Use the water ratio on the bag, do not add more water later, and keep the area warm and unused for the curing time on the data sheet.[1]
Start with where it is cracking
Grout cracks for a handful of reasons, and where the crack sits tells you which one. Cracks in corners and along the tub or shower base are usually a joint that should never have been grout. Cracks across the middle of a wall or floor point to movement underneath, to water, or to grout that was mixed or cured badly.
Corners and tub joints: wrong material
Movement joints are required for perimeters and other changes of plane in all installations.[1] Grout is rigid. Where a wall meets a wall, or a wall meets a tub, the two surfaces shift slightly with temperature, humidity and settling, and a rigid joint gives way.
Grout manufacturers say as much on their own data sheets. Custom Building Products lists its sanded grout as "Not for use in movement joints or changes of plane in the tile installation."[1] In these areas, use an appropriate caulk or sealant such as Commercial 100% Silicone Sealant or Ceramic Tile Caulk.[1] If the cracked joint is in a corner, the repair is caulk, not more grout.
Middle of the wall or floor: movement, mixing or water
LATICRETE's troubleshooting guide for cracked tiles or grout lists five causes: deflection in the substrate, improper installation of cement backer board, lack of movement joints, not enough thin-set on the back of the tile, and improper tile adhesive selection.[2] Most of those are installation problems you cannot see. A floor that flexes underfoot is the common one.
The same guide lists deflection in the substrate, movement or settlement of the substrate and lack of movement joints among the causes of loose and hollow-sounding tile.[2] That is why tapping matters: cracked grout next to a hollow tile is a symptom, and regrouting alone will not last.
Other causes are easier to fix:
- Too much water in the mix. The data sheet for a common sanded grout says "do not add water, which can weaken the grout, cause color variation and possible cause shrinkage, cracks and pinholes."[1]
- Grouting too soon. Tile or stone must be firmly bonded to a sound substrate, and setting material must be cured a minimum 24-48 hours before cement grout is applied.[1]
- Early use. The same sheet says not to open the grout to foot traffic before it has cured for 16 hours, and to maintain temperatures above 50 degrees Fahrenheit for at least 72 hours.[1] Showering the next morning is a common way to ruin a good job.
- Water behind the joint. Grout that is falling out of a shower wall, with dark staining or a soft spot behind it, can mean water is getting into the wall. Fix plumbing leaks and other water problems as soon as possible.[3]
What to do about it
If the tiles are solid, the repair is straightforward. Clean the area first. Scrub mold off hard surfaces with detergent and water, and dry completely.[3] Then rake out cracked or crumbling grout in the field joints and regrout, following how to regrout a shower. Corners and the tub joint get flexible caulk instead.
Once the grout has cured, sealing it helps keep water and stains out; see how often grout should be sealed.
Stop and call a pro if
- Tiles sound hollow, rock or lift. That is a bond or substrate problem, not a grout one. Regrouting over it just hides it.
- The floor flexes or the cracks run through the tile. Deflection in the substrate is the first cause on LATICRETE's list for cracked tiles or grout.[2] Fixing it can mean the framing, not the tile.
- There is a soft spot, a stain or mold behind the wall. Water in the wall is a repair for a licensed contractor, and the leak has to be found first.[3]
- The cracking keeps returning after a proper repair. Something is still moving.
- Large tiles are failing. Tiles larger than 8” x 8” (200mm x 200mm) require back-buttering for proper installation.[2]
Getting help in Virginia
Not sure whether it is a grout fix or a tile fix? Read should I regrout or retile my shower and what regrouting costs in Virginia. Loclis lists local pros for tile and grout repair, and you can browse more home repair answers.
When you are ready, describe the damage once and local pros quote it.
Common questions
- Why does the grout crack in the corner of my shower?
- Because a corner is where two surfaces meet and move a little against each other. Movement joints are required for perimeters and other changes of plane in all installations, and grout is not made for them. A flexible tile caulk or silicone sealant belongs there, and rigid grout in a corner will crack sooner or later.
- Can I just fill the cracks with more grout?
- Only if the cause is gone. Grout pressed over loose, cracked material rarely bonds, and if the crack came from movement or water it comes back. Rake out the damaged grout to a sound depth, find out why it failed, and regrout. Corner and tub joints get caulk.
- Can bad mixing make grout crack?
- Yes. The manufacturer's data sheet for a common sanded grout warns not to add water once it is mixed, because extra water can weaken the grout, cause color variation and possibly cause shrinkage, cracks and pinholes. Use the water ratio on the bag, let it slake as directed and keep the area warm while it cures.
- Does cracked grout mean my tile is coming loose?
- Not always, but check. Tap the tiles around the crack. LATICRETE lists deflection in the substrate, movement or settlement of the substrate and lack of movement joints among the causes of loose and hollow-sounding tile, and these also crack grout. A solid-sounding tile with a crumbling joint is usually a grout repair.
- How long should new grout stay dry?
- Follow the data sheet for your grout. One common sanded cement grout says not to open it to foot traffic before it has cured for 16 hours, and to maintain temperatures above 50 degrees Fahrenheit for at least 72 hours for proper cure. In a shower, keep water off for longer than you think you need to.
Sources
- [1] Polyblend Plus Sanded Grout, Technical Data Sheet TDS-360 (published 3/22/2023), Custom Building Products. Checked October 28, 2026.
- [2] Thin-Set Troubleshooting Guide for Cement Backer Board Substrates (TDS 208, revised 19 May 2023), LATICRETE. Checked October 28, 2026.
- [3] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency. Checked October 28, 2026.
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