"Please give me an estimate to reattach a few cracked tiles" is a common phone request we get. Usually the client indicates that a few tiles have cracked or fallen off, and are either at the bottom of the pool or have been netted out over several months and kept for re-installation. As I return these calls I always let the customer know that cracked, loose or dislodged tiles are usually the sign of some underlying condition. Plain and simply a well installed pool tile does not typically fall off. Often a loose tile involves a horizontal crack about 2 inches below the coping and extending visibly for anywhere from just a few tiles to the entire waterline of the pool or spa. Below are 2 photos of just such a tile at the spa waterline of a recent pool remodel we did for a customer. In the first picture below you can see a crack in the pool structure behind the tile.
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| This crack was so deep I could bury my entire index finger into it |
In the this next picture you can also clearly see tree roots growing through the crack.
It would be easy to assume that the roots had somehow forced their way
through the concrete and pushed the tiles off, but that is not the case.
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| Here we see root hairs extending through the pool wall indicating the crack reaches the earth on the far side |
As you can see in the following 5 pictures taken as we pulled off the pool
coping, the mortar bed under the pool coping surrounding the entire
pool was cracked at the same level. Tree roots were found in some areas but other areas were root-free.
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| After removing the coping the loose mortar bed was "chased" out with a pick |
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| Once removed we see root infiltration on a level plane |
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| Moving towards the spa we found that even with few to no roots visible the same "cracked" condition continued |
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| As we work around the spa we started encountering roots again |
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| Once past the spa the roots again dissipated but the separation continued |
In this case the roots came after the cracking occurred and this is evident by the fact that there are areas where there is a crack with no roots present. That poses the question; what caused the crack if it was not the roots' fault? The engineering diagram below which we borrowed from the
Pool Engineering Inc website shows the real culprit; an improperly constructed expansion join.
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| The illustration at lower right shows how the expansion joint failed to protect the pool from the deck due to the expansion material not extending the full depth of the deck thickness; during warm weather the expanding deck pushed on the pool and cause the crack to occur along the weakest link, which in this case was a poorly adhered mortar bed into which the coping was set. |
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In the center of this picture you can see where the depth expansion joint ends far above the depth of the concrete deck itself. The deck was in physical contact with the mortar bed which caused the crack. Further compounding this scenario was the fact the the top of the pool wall was not sufficiently cleaned to allow proper bonding between the mortar bed and the pool wall prior to the mortar bed being set, but regardless of this fact this pool was doomed to failure.
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| In the left-center of this picture you can see where the concrete deck is in contact with remnants of the old mortar bed. The same is true for the "point" of the deck at the extreme lower left. Although the roots are invasive they did not cause the cracking; they merely came later to find an easy drink. |
To properly repair this pool we removed all of the coping around the entire pool and spa. New coping was installed with care taken to be certain that a new foam expansion joint was in place and extended the entire depth of the pool deck to allow for seasonal expansion of the deck. Once the coping was installed a mastic (special pool caulking) was applied at the top of the expansion foam to provide a flexible and weather-proof barrier to keep water out. Before the mastic cured we sprinkled clean #30 silica over the mastic to protect it from drizzle and critters while it cured and to give the appearance of mortar rather than plastic.
