Expert Answers
Why do my Pool Water Line Tiles have pits in them?
QUESTION
We have a plaster pool that was re-done about 7 years ago. the health department made us make the pool shallower. We are in the mountain and have lots of snow. We have a row of tiles under the coping. Two years ago, in the spring we noticed that many of the tiles had fallen off. We had them all removed and had workers install new tiles. This spring now we have pitted holes in the tile. Some are large and some small with no pattern. What could cause this? One of the workers on the re-do of the pool had said something about water behind the tiles?Thanks for any advice.
ANSWER
ANSWER - Being in the mountains and having your pool subjected to snow and freezing conditions would suggest that your pool waterline tiles are not freeze-thaw stable.Meaning that the tiles are porous enough that they absorb moisture. If the tile absorbs moisture, then when there is freezing temperatures the moisture freezes. When the moisture freezes it expands and can cause the tile surface to spall/pit.
Nothing you can do about it. If you replace the tile make sure you use a porcelain tile that has less than 0.5% absorption and is rated as freeze-thaw stable.
3 thoughts on “Why do my Pool Water Line Tiles have pits in them?”
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Currently in the middle of a pool build in NE PA, and our Pb subcontracted the waterline tile, spillway, and coping. We are using NPT porcelain tile but noticed subcontractor using the glob and stick method, which left voids behind each tile. This caused tile to look unlevel and when brought to our builders attention, they claim this method is acceptable and thin set troweled on the gunite isn’t the only method to apply. We are demanding a redo and replacement. They said they will do it at a charge to us. Can you tell me where in the ANSI standards I can point to explain this method will lead to water intrusion and failure?
In the American National Standard Specifications for the Installation of Ceramic Tile states in ANSI A108.5-2023, section 2.2.3 that all tiles installed in the exterior application or in an interior wet application that the thinset coverage must be 95% with all edges and corners fully supported with the thinset.
In the Tile Council of North American Handbook for Ceramic, Glass, and Tile Installation detail P602-25 for Pools and Water Features, it states that Tile bond coat coverage shall be a minimum of 95% contact between the tile and its substrate.
There are other ANSI A108 standards for workmanship that would require the tiles to be installed in a plumb and flat manner with substantially no lippage greater than 1/32″ on a mosaic tile.
You can not rely on the installers being aware of industry standards and performing the installation properly. You need to provide the quality control oversight or to higher a company like CTaSC to provide those services.
Thank you. Is there somewhere that shows the proper installation of waterline tiles to a gunite surface? Pool builder is insisting subcontractor used the correct method. From what I have seen, there are multiple layers prior to thinset being applied. It appears these guys installed thinset directly to the back of the tile and stuck it onto unprepared raw gunite surface, leaving visible voids.