Why Is My Grout Crumbling? What pros say

Seeing your grout start to crumble can be a very sad sight. You’re probably extremely confused as to why this is even happening. There are several factors that could cause your grout to crumble—luckily, you can prevent most of them.

Your grout may be crumbling because it wasn’t mixed properly. If your house was built recently, the foundation settling could also be a culprit. Letting the grout dry in an overly humid environment can cause improper curing and lead to cracks in the grout.

In the rest of this article, I’ll go into detail about the many factors that could cause your grout to crack and some solutions for this problem. There’s no easy fix for cracked grout, but there are things you can do to prevent the cracks from forming in the first place.

The Grout Wasn’t Mixed Properly

Grout is made from a mixture of sediment to create a concrete-like paste. Each manufacturer has different instructions on how to mix that particular brand of grout. If you don’t follow the manufacturer’s instructions to a tee, you could end up with grout that crumbles when dried.

If too much or too little water is mixed into the grout solution, it will make the grout much less structurally sound. That’s why you need to follow the manufacturer’s instructions when mixing grout.

● How To Prevent

The mixture should have the consistency of smooth peanut butter or a thick cake batter. It should not be runny when the putty knife is pulled from the mixture, but you should be able to stir and work with it.

Making sure that your grout is mixed properly is the best way to prevent the grout from crumbling.

Another essential part of the grout laying process is to properly seal the grout. You should carefully apply the sealant to the entirety of the grout.

Sealing the grout will protect it from water damage. It will also add a layer of protection next time you scrub the grout to clean it.

The Grout Was Left To Dry in a Humid Environment

Grout needs the right environment to dry and cure if you want it to last a long time. When the grout is left to cure in an environment with too much moisture, it will significantly affect the finished product.

Suppose grout is allowed to dry in a humid environment with a lot of moisture in the air. Due to its porous nature, the grout will absorb the moisture. The humidity in the air will penetrate deep into the grout, and if you seal it after this happens, you will be sealing all of that moisture into the grout.

This will not only open the grout up to fungal growth like mold and mildew, but it will also greatly deteriorate the structural integrity of the grout. The water that has been sealed into the grout will weaken the grout and cause it to deteriorate much faster.

If you let mold grow inside your grout for enough time, you could end up with permanent stains and even a foul smell.

● How To Prevent

Grout dried in a humid environment will inevitably break down more easily and crumble over time. Grout should be dried in a well-ventilated environment with the least moisture in the air possible.

You can accomplish this by running a fan or opening a window in the room where the grout is drying. You can also place a dehumidifier. This will keep the air dry and free of moisture, providing a perfect environment for the grout to dry properly and remain strong over time.

The Foundation of Your Home Is Shifting

This may seem like an outlandish cause for cracked grout. However, it’s actually fairly common in homes that were recently built. Usually, the home’s foundation is shifting, but the walls remain still, causing cracks and crumbling in the grout.

Those creaks you hear at night that make you think someone is creeping around your house could be the sound of the foundation shifting. This doesn’t mean there’s anything wrong with how the house was built—it’s just the way some houses age.

If the settling of the foundation has caused cracks in your grout that are making it crumble, it will usually cause cracks in the tiles as well. That is a telltale sign that your shifting foundation is the cause of your issues.

How To Fix

If this is the cause of your damaged grout, the damaged section of the grout will need to be removed and replaced. The new grout should match the color of your existing grout.

A professional will do a better job at performing this task, but if you do have the proper tools, you can do this yourself. You’ll need a tool to cut through the grout effectively without damaging the surrounding tile, and grout saws are made precisely with this purpose in mind.

Using a grout saw can be very dangerous, so you must proceed with extreme caution if you do it yourself. Take your time and work slowly and deliberately, keeping your hands free of the blade. Don’t forget to wear protective gear for your eyes.

The potential for severe personal injury or further damage to your grout or tile is why this process is best handled by a professional. They’ll have all the proper tools for the job and know how to use them safely without hurting themselves or your grout and tile. 


Grout will crumble for many reasons, but most are easily prevented by properly mixing your grout and properly sealing it. 

You should also make sure that the room where your grout is drying is well ventilated and free of humidity. Grout that is allowed to cure in a humid environment will absorb the moisture from the air.

Another cause for cracked grout is the foundation of your home shifting. In this case, you’ll need to replace the damaged section of the grout, which should preferably be done by a professional.

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