What Causes Grout to Break Up?

Grout, the mortar that fills in the gaps between tiles, can last for decades when mixed and applied properly. However, it can crack, crumble, or otherwise break up after being installed.

Homeowners and business owners can become very frustrated when grout starts breaking apart in a tile floor. The problem can feel even more disappointing when installers completed the tile installation only recently.

As grout cracks or crumbles, the gaps between the tiles become more noticeable. The floor may begin to look worn, damaged, or poorly maintained. Loose or deteriorating grout can also raise concerns about the long-term durability and stability of the tile installation.

While it’s easy to point fingers about what caused the problem, it’s more important to try to identify the cause, so that repairs can get started.

Causes of Bad Grout

Here are 4 causes for why the grout between tiles may be breaking up:

1. Improperly mixed: Installers mix powdered cement with water to create the paste placed between tiles. If installers use the wrong ratio of water to cement, the grout mixture can become unstable and weaken the binding agents.
2. Old mix: Old mixtures will often result in weakness, and this can lead to crumbling and cracking over time. In addition, inconsistent mixtures between old and newer varieties can lead to problems.
3. Defective mix: Manufacturing errors can create an imbalance in the ingredients used to make the cement. When installers mix the defective cement with water, the grout mixture may weaken and fail over time.
4. Subfloor deflection: Installers must meet certain conditions and standards when preparing a subfloor for tile installation. If the subfloor does not meet those standards, floor deflection, movement, or excessive bounce can cause grout and tile to crack over time.

Repairing Grout Problems

Repairing cracked or crumbling grout requires removing the old stuff between the tiles and applying fresh, properly mixed grout. The grout is applied between tiles just as if they were being laid down in a brand new installation. For subfloor issues, the repair is more intensive and includes major adjustments. It’s best to leave that to professionals who know what it takes to repair the problem.