Angie explains causes of loose grout

Dear Angie: I put tile on my shower floor but the grout keeps coming loose. What did I do wrong and how do I remedy this? – Carole N. Rockford, Minn.

Dear Carole: There are at least six things that could be causing your grout to come loose. In most scenarios, you’ll unfortunately likely have to remove the old grout and re-lay your tile.

  1. Newly poured grout usually requires at least 24 hours to dry and a full week to cure before it is sealed. Deviating from the proper drying/curing time as detailed by your grout manufacturer can affect the durability of your grout. If this is your problem, you’ll need new grout.
  2. Loose tiles will cause grout joints to crack. If the tile is loose, it could be because it did not achieve a good bond with the thinset mortar or did not get sufficient coverage. If this is your problem, removing the loose tile and installing new tile would be the answer. Highly rated tile installers I’ve talked to recommend using 100 percent silicone rubber caulk around the perimeter of the shower floor to the wall tile.
  3. If you have sheet-mounted tile, it’s possible that the silicone tabs that hold the sheet together might be too close to the surface of the tile and are not allowing enough depth for the grout. If this is your problem, you may need to remove the existing grout and re-grout with an epoxy grout.
  4. Houses move and shift slightly over time. If your subfloor is not secured properly, house movement could cause the tiles to shift, which would cause the grout to crack or flake. A good indication of this is if the tiles themselves are still securely mortared down and are not coming up. A flooring professional can inspect the subfloor to determine if it is properly secured and, if it is not, suggest the best course of action to secure it.
  5. If you find moisture under your tile, it could be that the shower pan was not installed properly. You’ll want to call out a bathroom remodeling contractor to inspect that if you believe that is the case. Most likely, assuming the shower pan is installed properly and there is no moisture under the tile, the issue could be the wrong type of grout was used. If the grout joints are bigger than 1/8-inch, you need to use sanded grout. If the grout joints are less than 1/8-inch or less, you want to use non-sanded grout. If non-sanded grout was used in bigger grout joints, it will not stay in the joint.
  6. There’s also a chance that the grout itself may be old or may not have been mixed properly. When a bad batch of grout is put in, it will not setup properly and can flake or crumble out of the grout joint. If this is your problem, you need new, properly mixed grout.

Clearly you have a lot of different scenarios that could be causing your grout issue, Carole. I recommend finding a reputable tile installer to inspect your shower before you do anything. A reliable installer will clearly spell out the problem and give you options for a remedy that fits your budget.

Angie Hicks is the founder of Angie’s List, a provider of reviews you can trust on contractors, doctors, dentists and other service professionals. More than 1 million consumers across the U.S. use Angie’s List to help make tough hiring decisions easier.

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