Need help understanding how pool/deck/coping are supposed to interface

[zz28zz]

Pool built in 2000. We moved in ~2010. At shallow end, the water line tile (6"sq) was popping loose. After the tile fell off, saw there was a crack/joint roughly half way up the tile and extended 6+ feet. Thru this "crack" were roots coming into the pool. Had it "fixed" during plaster job. It was OK for a while then the exact same thing happened.

We had red 12" bull-nose brick for coping and a concrete deck around that with cool-coat installed. 1st pool guy came out and said he could fix it but wasn't able to source the red brick to put it back together. I couldn't find it either. Went with a different guy and decided to replace cool-coat with limestone over the entire pool area. So now we have 2" thick limestone all around the pool and the limestone over hangs into the pool an inch or so.

Deck guy was supposed to re-plaster the pool. After deck was almost done and pool had been drained for weeks, he disappears along with abt $10K and left a huge mess in the driveway. Got a new guy to do the re-plaster and finish the deck area. Spoke to the new guy abt the crack/joint opening-up behind the water line tile. Suggested maybe the deck needs a relief cut to relieve stress and prevent deck from possibly bow'ing-up. He said he would use something I never heard of before and proceeded to tile and re-plaster pool. Went with 1x2 tile this time. 6 weeks later, I saw the grout cracking exactly where the crack/joint was located. They came out today and patched it up..

Now I'm trying to understand if this "crack" is really just the joint between the pool structure and the deck and the deck is lifting/shifting for some reason. From what I have gathered so far, the main pool structure rarely moves, but the decking can. It appears to me the tile is overlapping the moving and non-moving pieces, I don't understand how this is supposed to ever work. What am I missing??

 

[AQUA~HOLICS]

Can you provide a picture of effective area?
The deck work is not to come in contact with the coping, an expansion joint is to be in place to let the deck work move independently from the coping.
If the deck work is in contact with the Bond Beam when expanding, the Bond Beam will crack due to the pressure applied to it.

 

[ajw22]

The deck and pool need to be able to move as two independent structures separated by an expansion joint.

The deck putting pressure on the pool structure is what causes the cracking you get.

Expansion Joints and Coping - Further Reading

www.troublefreepool.com

 

[zz28zz]

That cut-away and link helps but I still have no idea if it was built right to begin with.

There was an expansion joint between the coping and deck when we had brick coping and we still had the issue. I remember they had to replace the expansion joint mastic and it was pretty expensive stuff. Maybe that mastic doesn't go all the way down to bottom of concrete deck??

To make matters worse, it's all been covered up. The last time around, the brick coping was removed and built up level with the deck. Then they layed limestone on top of the concrete deck and over where the brick used to be so it protrudes into the pool area like a cantilever deck. No idea if they ensured expansion joints. Workers didn't speak english and foreman/owner is MIA. Not sure what to do now. I'll try to post some pics from my phone.

 

[zz28zz]

Pics from 6 weeks after tile work and re-plaster but before "fix" was done today. Only a small area in pics but crack extends 5-6 feet.

 

[ajw22]

We don’t have X-ray vision to tell you what the buildup of your deck is.

The symptoms and cracking you describe are all indicative of coupling of deck and pool structures. If the contractors do not know what they are doing and don’t care it is easier to connect the structures then be deliberate in keeping them separate.

 

[tommelton]

This is why taking pictures as the work is done is critical. As they demo'd and rebuilt your deck and tile work - someone in the family should have been taking pictures along the way.

 

[zz28zz]

Being totally ignorant of how pools are built, I orig thought the deck was on top of the pool structure when I saw the crack behind the water line tile. This is where the confusion began since the crack was very clean/straight and initially appeared to be a mating surface. I assumed something lifted the deck off the pool structure and allowed the roots to enter. Now I understand the expansion joint failed for some reason and allowed the deck to push on the pool structure causing the crack in the pool structure and roots to enter. Got it.

In regards to recovery, wondering if it's possible to cut down thru the new limestone deck along the line of the old expansion joint below (where the brick coping orig mated to concrete deck) ? Verify deck has clearance to the pool structure all the way down to bottom of concrete deck, then fil gap with foam rope and new mastic (matching grout color) at the top of the deck. This would effectively transform the new limestone deck above the pool structure into the "coping". One issue I see with this "easy" method is the expansion joint isn't straight since the pool curves continuously, so cutting/grinding down thru the limestone and staying on point would be challenging. May be better to demo the new limestone out to the expansion joint?