Why Is My Grout Falling Out? 5 Causes and Tips to Fix It

Nothing beats walking into a bathroom or kitchen with gleaming, perfect tile bonded with smooth, clean grout. But if your grout is loose, it's not only unsightly—it can be dangerous, leading to slipping hazards and even mold. That's why it's essential to understand what causes loose grout, find out how to spot it, and learn how to repair it.

This guide breaks down some of the most common causes of loose grout and offers telltale signs on how to identify and fix it so you can enjoy the look and feel of that seamless tile.

What Is Grout?

Grout is a mixture of water, cement, and sand that fills the gaps between the tiles throughout your home. It's basically the glue that holds everything together in those areas, so if it's loose, you'll notice it. A homeowner or professional usually mixes these materials together and applies the grout when wet, allowing it to set over a certain period.

Signs of Loose Grout

These telltale signs should help you determine once and for all if you have loose grout.

Loose Tiles

Tiles should never be loose. The grout should firmly anchor them in place, so if you can feel movement in the tile when you step or push on it, that's an indication of loose grout. Loose tiles are a tripping hazard, and can result in additional problems down the road—a few issues now can spread through the whole floor and cause widespread damage over time. Reinstalling the tile with new grout may be necessary, and if it’s a small enough fix you can do it yourself, but consult with a professional first if you are unsure whether you should attempt to fix it on your own.

Mold

Grout should provide a seal between the inside of your tiles and the outside world, so if you're seeing mold develop quickly, that's a definite sign that moisture is seeping through your loose grout and causing the mold.

Cracked Grout Lines

If you can see damage to the grout, such as cracks or deterioration, you should consider having a professional come take a look. It's possible the grout was installed improperly, or that there are issues with substrate deflection (an industry term for the bending of the underlying surface), but either way, you should address it.

What Causes Loose Grout?

There are many reasons why your grout can become loose, ranging from how it’s mixed to how it’s installed to the environment in which it was installed. Here are some of the most common reasons for loose grout.

1. Structural Failure

If the floor shifts beneath the tile, it could cause the grout to become loose. And while it’s not as common a problem with walls, structural failure is sometimes to blame for loose grout in those areas.

2. Insufficient Packing

When you install grout, you really need to pack it in there good and tight. If you don't use enough force, the grout may not penetrate as deeply as it needs to, leaving the grout with little overall strength and making it susceptible to loosening later on.

3. Too Much Water in the Mix

If the installer mixes too much water in the grout, or uses too much water while dressing the joint, the grout may fail.

4. New Grout Installed on Top of Old 

When you install grout, it’s vital that you scrape out as much of the old grout as possible. If you don't, the poor-quality grout underneath will undermine the strength of the new grout you put on top of it.

5. Moisture Seeping In

Cement is porous, so grout must be sealed before it can be exposed to moisture. If the grout was applied after moisture already seeped into the cement, it could cause the grout to lose its structural integrity.

How to Repair Loose Grout

You can repair loose grout even if you’re a beginner DIYer. You’ll need a grout float, grout or rotary saw, new grout mix, sealant, and a damp towel. (But if using a grout saw or mixing grout seems a bit intimidating, let a pro take this project on instead.)

1. Use a rotary saw to cut out cracked and damaged grout, then vacuum the area.

2. Spread the new grout evenly over the grout lines with a grout float.

3. Remove excess grout with the edge of a grout float for smooth lines.

4. Wait five minutes for the grout to settle. Then, clean the area with a damp towel. 

5. Apply a thin coat of sealant with a sponge, wiping away excess before it dries.

When You Should Hire a Professional

While this can prove a do-it-yourself project, if you have widespread issues with loose grout, problems with mold, don’t own or want to purchase the necessary tools—or you’d rather do something else with your Saturday, consider contacting a grout repair professional near you to come out and take a look. They can do a deep inspection, make some recommendations, and provide you with a quote.

With this knowledge in hand, you can determine whether you want to move forward with hiring a professional, or if you'd like to take a crack at doing the job first yourself.