Since you noticed it when you opened it up, what did the builder say months ago when you noticed it?

Seems a bit odd you bring it up in September.

He said he would use silicone in the joints but wait to see if there was further settling. I was asking for advice do you have any? I don't think it's odd to want a new pool installed properly.

Thank you for the useful information Iconic Design!

Is this a natural stone coping around only the edge of the pool? Do you have a picture from the top you could share? What did the builder attach those stones with - I am guessing construction adhesive (epoxy). It looks like it has failed either from delamination or from freeze / thaw conditions. Is it cold in the winter where you are? Take a hammer or something heavy but not sharp, and drag it around the pool on the surface of the coping stones. The delaminated ones will sound very hollow. How much of your coping has delaminated? Waiting until next year may be the contractor trying to push the problem past his warranty period. Make sure everything is documented in terms of your communication with the builder regarding this issue.

Thanks for your reply SwimmingpoolSteve: It is a cantilever concrete coping. It's pulling up from the top of the pool. By the steps I can see the top of the pool (the white metal tract- screws and all) and then there's a smaller gap all the way around to the deep end. The PB wants to seal the gap with Vulkem expandable material. He hasn't offered any remedy for the uneven coping-blaming it on a sprinkler in the area.

Could be one of several reasons.

The base under the concrete might not have been properly compacted and now the slab is sinking. Is the other end of the slab lower than its neighbors?

The base under the slab could have eroded away due to water.

If the base material under the slab doesn't drain well and holds water, there's a remote chance that the slab could have heaved during freeze/thaw cycles. Depends on your climate.

Slab curl probably isn't a factor since is was good for half a year.

Can't really assess fault until the reason for the separation is diagnosed. If the builder is simply offering a band-aid fix, that's not good. Simply blaming it on the sprinkler? He needs to explain what exactly the sprinkler is doing to have caused this.

Thank you MongoCT. Yes the other end of the slab is sinking. I'm in NJ so it could of heaved during freeze/thaw cycles. The PB is trying to say the sprinklers have a leak but the sprinkler system was winterized and shut off for the winter. It's funny how he's not saying any reason for the settling of the deck by the steps because according to him "that's an easy fix with sealer". He's trying the place blame everywhere else but his workmanship.