We recently put a pool and raised spa in our backyard. The coping is flagstone (not the Oklahoma or other regular kinds I typically see, but it’s super sturdy...) and around the outside of the spa is natural stacked ledger stone. Our contractor says that he isn’t going to connect the flagstone and ledger stone with anything - grout, silicone, whatever other options are out there - because he says it needs to be able to stay flexible in case if an earthquake (I’m in Southern California). I think it looks very unfinished. It’s uneven because the flagstone is left in its natural state...varying widths...and therefore the ledger stone isn‘t even up against it. it seems to me there should be some way of making it look polished/finished without making it unable to be flexible during an earthquake...but maybe I’m wrong? Our contractor has left us hanging on the last several steps of this job for the past month, so I feel like he just doesn’t want to do any more work and he’s trying to give me a bogus excuse. Please - someone who’s actually knowledgeable - help me!

I’m attaching a photo so you can see how uneven the space looks between the two kinds of stones. Photo was taken at night after my kids were in bed, please excuse the poor quality.

Thank you in advance of any help you can provide!