What is causing my Tile to Discolor in our Shower?


What is causing my Tile to Discolor in our Shower? I recently re-did both bathrooms (I hired someone) - I used the same floor tile in the shower. Several weeks after install, full tiles in shower became discolored, and it keeps happening - up to eight pieces of tile so far. No one seems to know what happened?


ANSWER - There are a number of variables involved in determining what is causing the discolored tiles, and it will likely require some intrusive inspections to verify the cause and to determine how to remediate it.

You didn't indicate whether the tile is a glazed ceramic tile or an unglazed ceramic tile or whether either of those types of ceramic tile were porcelain body tiles. Tile could also refer to a natural stone that can be one of many different types of stone with different geological classifications and physical properties.

You also didn't indicate whether the discolored tiles are on the floor or on the walls or other horizontal surfaces.

Natural stones are more likely to show discoloration in showers under the wrong conditions. Although ceramic tiles with more porous bodies can also show discoloration. The floor tiles are more likely to show discoloration than tiles on walls, but you can get discoloration on walls particularly where the wall tile meets the floor tile.

Sometimes when there are fully discolored tiles it is generally due to them being continuously wet, which can be caused by the weep holes at the lower part of the drain being plugged because a weep hole protector was not installed during the installation. This can show up on the shower floor and at the lower portion of the walls near the shower floor.

There are other types of discoloration that can be caused by other conditions, which is more likely found in natural stone installations. The only way to determine for sure what the problem is and how to fix it is to perform a forensic investigation by removing some tiles under various conditions to look for the evidence.

10 thoughts on “What is causing my Tile to Discolor in our Shower?

    • Donato Pompo says:

      The cementitous grout is porous so it can more readily stain and more readily absorb moisture. The dark grout might be the result of something staining it from the surface of the grout or it could be a stain migrating up from under the tile.

      If the dark grout joint has high moisture content it might be an indication that the water is trapped in the underlying mortar bed and the darkness could be a microbial stain.

      You can try cleaning it with a neutral detergent with a bristle brush to dry cleaning it and then see if it returns. You can apply clear plastic sheet over the area and tape it down to the floor and in 24 hours see if condensation develops on the bottom of the plastic.

      If the weep holes of the underlying drain are plugged and the water is trapped then the tile around the drain will need to be removed.

  1. John Boy says:

    I had my walk in shower torn down to the studs and replaced, including a new fiberglass pan. We had subway tiles installed. After a couple of months, several wall tiles along the bottom of the shower walls began to turn a darker color than the other tiles. We spoke to the contractor. He thought they might be defective tiles, so his guy came in and replaced them. A month later, those tiles also changed color. We suspect the problem is one you have suggested in the past – the pan was not installed properly so water must be pooling under the floor near the edges of the wall where the tiles are becoming discolored (we assume they are turning color because they are constantly wet). The contractor insists that is not the problem and no other tile contractors or tile stores have ever heard of this being a problem. How do we find someone in our area (central NJ) with some authority to diagnose this so we can convince our contractor that this is the problem?

    • Donato Pompo says:

      Your description suggests that there is a problem in how the tile was installed in terms, which may include the products used, the configuration of the tile assembly and in how it was installed. Generally speaking when there is a problem it is never due to a single deficiency, but rather due to multiple compounding deficiencies.

      The only way to determine what are the conditions/deficiencies and to determine how best to remediate the problem is to perform an intrusive forensic by removing a few tiles in various spots. This isn’t always practical to do in terms of the costs.

      First you need a company like http://www.CTaSC.com who are experts, very experienced, and honest, which there are not many around. We do have inspectors throughout the country so we might have someone relatively close who will perform the inspection for me. Sometimes it is better to spend the money on replacing it rather than fighting it.

  2. David L Fawcett says:

    Maybe if you have a piece extra of tile lay it down in a pan of water to see if it darken the same as your wall tile. My thought is yes water is soaking up into ceramic tile. Here idea ceramic tile absorbs water and mosaic does not’ replace discolored tile with mosaic tile

    • Donato Pompo says:

      I have seen where glazed non-vitreous tiles, which are tiles that can have an absorption of more than 7% to not more than 20% can have its glazed surface darken from being subjected to excessive moisture. Most glazed wall tiles will not darken from being subjected to moisture.

      The best way to remediate this is by replacing the dark tiles with new tiles if you have left over material available. During the replacement paint the back and edges of the replacement tile with a liquid applied waterproof membrane. This will keep the moisture from getting into the tile so it won’t darken.

  3. Bella says:

    This is happening to me and I am worried about leaking…… if the tiles are continuously wet and change color, does that mean there is moisture in the wall behind it? We used a detector and it did t seem to detect any but when we didn’t use our shower for a month the tiles are now white again. I don’t care about the color but just do not know if I need to replace shower to prevent damage/leaking or is it ok if tile is continuously wet.

    • Donato Pompo says:

      If your ceramic tiles or natural stone tiles are darkening after being wet that would indicate that they are absorbing moisture that shows through the surface of the tile. It might also suggest that water is being retained behind the tile for some reason such as excessive voids or a porous mortar bed that in effect subject the tile to to prolong moisture. Or that the wall substrate is directly connected to the shower floor that allows water to wick up rather than having a moisture break there as there should be. It doesn’t mean that water is migrating into the wall cavity. Whether that is happening or not, you can’t tell by looking at the completed installation. You should have to remove the tiles to intrude into the wall or enter the wall cavity from the back side of the shower wall making a small hole and inserting a borescope to view inside.

  4. Megan says:

    We are having this issue too. Is there a way to submit a photo? Any professionals in the Minneapolis metro to consult with? The bathroom is just 2 years old.

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