Cracked tiles resulting from bond beam rot

[bmoreswim]

Cracked tiles appeared last year in two areas along one wall. Our pool is 11 years old and otherwise in very good shape. So I started conversations with our builder who is available but not building pools any longer. We weren't able to determine the cause until the area was demolished down to solid shell concrete. The two causes could have been expansion of the concrete deck along that side, which is 12' wide, expanding into the coping/top of the shell, or bond beam rot. The reason deck expansion was possible even though there was an expansion gap, was that the gap was much smaller along that side versus the other 3 sides of the pool. On the day they poured the deck, there was not enough of the thicker foam available to provide the gap, so they used thinner foam. The other possible cause was bond beam rot. This is most often caused by using rebound (gunite that fell to the floor that is picked up and placed on the shell but lacks the compacting element of it being shot from the nozzle) at the top of the shell. Another cause can be water infiltration and the repeated freeze cycle eventually weakens the concrete structure.

Upon demo, they used a hammer drill with a star bit and worked their way into the bond beam. It had occasional chunks but was much more so sandy/gravelly in nature, pointing to bond beam rot. Long story short is that we agreed it would be much more straightforward to have a crew he new was very competent do the work and not try and pursue the issue with the gunite company. Since my mastic was also overdue for being replaced (also 11 years old), that could have played a factor. The cracking areas were adjacent to each other on the upper side of the pool. Though tiles on the opposite side also have some hollow sounds, we opted not to address what was not presenting as a cosmetic issue. If there's already an underlying issue, the fix will be the same regardless if it is done now or later - mobilization for the job is minimal as are water costs. So we'll leave well enough alone on that side.

Our tile was also no longer available so we chose something close and opted not to go with a full tile replacement. The time will come in the next handful of years or more/less where it all needs replaced and perhaps additional bond beam rebuilding will take place then also. At that point, we would also get the plaster replaced, whereas now it's still quite smooth for plain plaster after 11 years. In frost zones, tile doesn't last forever in most cases. So the tile is mismatched, but its not a big deal. We aren't perfectionists.

Original views of a cracked tile area and of an adjacent area where I pulled off the tiles to reveal a crack (click to expand). The crack is not flat on the surface, but pushed out about 1/8", causing the cracked/loose tiles.



Here's the in process shot. Much happened after day one while I was not on site. A complicating factor was the autocover track crossing the area. They did the repair in two sections so the track could remain supported. They epoxied in fiberglass coated rebar to join the old and new concrete.



And the finished product...again, the tile mismatch is what it is. I was very pleased with the quality of work and jobsite cleanliness.




One water truck is coming today so I don't put the full refill responsibility on my well. Now I just need a caulking guy to call me back. $4K labor and material.

 

[ajw22]

It is interesting that your tile was stuck on well enough that the tile cracked rather then pop off.

I think the tile mismatch is hardly noticeable once you get water in the pool. The new tile is on a long enough stretch that only when you look at where the old and new tile meet do you see the mismatch.

Did you get any warranty consideration on the repair?

 

[bmoreswim]

Good point, even the exposed area I took most of them off myself. There was some consideration in the labor rate, but overall, I went with people I trusted and less stress.

On the tile color, they always say no one uses the deep end of a pool anyway, so no one should really see the color difference, especially since it's on the house side.

 

[bmoreswim]

So, the project didn't wrap up quite as we hoped. The tile and coping are good, but then we had mastic removed and installed by a contractor as it was 11 years old, cracked, and no longer forming a waterproof joint. It was 100 that day so surface temps were 130+, and apparently, too hot. The caulk bubbled in many areas that were in the sun (most areas). The bubbles are still closed so it's all water sealed but my understanding with the contractor is that he will redo the job in the fall. We paid $11/linear foot which is on the high end I believe. The total was 180' since we also have expansion joints and areas around some walls. Quality of work was great until the bubbling. The picture below is a little exaggerated because of the low sun angle but it's also readily apparent at noon. The bubbles are softer than the non-bubbled areas and I'm sure will degrade quicker. For reference, the product he used was Sikaflex-1A.