What Are the Causes of Water Under a Tile Floor?

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Tiles are a popular choice for a bathroom floor, as they tend to stand up very well in a wet environment, but in spite of their resistance to water, water damage to tiles can still occur over time. Understanding the causes of water under a tile floor can help you to better deal with the issue at hand. Knowing the general causes of water damage to bathroom tiles can also help you to take care of your floor and prevent future issues.



There are a few different causes of water under tiled floors, including leaks, draining issues and damage to your grouting or tiles.

Signs of Water Under Tiles

Before determining the cause of water underneath your tiled bathroom floor, you first need to know how to notice the problem. There are a few different things for which to look that will indicate your tile floor is experiencing water damage.

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Loose tiles are a clear sign that there may be water underneath your bathroom flooring. Water can weaken tile adhesives and cause your individual tiles to move about or even come free. If your tiles are moving and there's no indication of water or flooding on the floor's surface, it's definitely a warning sign of potential water damage below.


You may also notice your floors warping or dipping. Water damage to your subfloor can cause it to change shape, which can create an uneven look on your floor's surface. You can sometimes notice damage to your subfloor from below via a crawlspace or basement.

You should also keep an eye out for any unexplained mold. Mold growth occurs quickly in damp areas, and if your floors are kept clean and dried regularly, any mold outbreaks could be attributed to water underneath the tiles.


Leaks and Draining Issues

The primary cause of water underneath your bathroom tiles is a leak. Some bathroom fixtures are plumbed into the main line underneath the floor, so if any of these connections become loose, water can end up collecting beneath your tiled floor.

Diagnosing hidden leaks can be tricky, but there are tips that can help. Try to see where the water damage is the worst, and then you can work backward to see from where this leaky pipe comes. You can also look for any dripping in the room below or any water pooling around different bathroom fixtures.


Another common source of water damage to bathroom tiles is a problem with your bathroom drainage. Homes in which the bathroom is more exposed to the outside of the home could be prone to water getting in from outside and causing damage underneath bathroom tiles.

Issues With Grouting and Tiles

If you're sure the water under your bathroom tiles is not caused by leaks from below, it could be that your flooring is not as waterproof as it once was. Damaged grouting can allow small amounts of water to seep underneath your tiles, which can cause big problems over time. If you notice an area where your grout looks damaged or not properly watertight, it's important to regrout your floor as soon as possible.


Alongside issues with grouting, your tiles themselves can become damaged and allow water through. Look for any cracks in your tiles. Even the smallest of cracks could cause water to get through to the underside of a tile and spread throughout the tiled floor. If you do notice a crack in a tile, you should always aim to replace it right away to prevent water from spreading under a tile floor.




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