We noticed recently that the corner bench in our shower had a sizable crack in the sealant along one edge of the support wall. Our first thought was to simply reseal the crack, but as I examined it a couple concerns crossed my mind. And I wanted to get better opinions.
Is this structural, and does it need to be rebuilt to keep the seat stable? I don't know what typically goes behind these kinds of seats to hold them up, but it seems that corner is pulling forward. This makes me think it might continue to slide forward, which means both that this problem will return (soon), and the seat will eventually fall.
Do I need to chase moisture out of there, before sealing? Because of the way water typically runs off the seat, it is VERY possible for water to run straight into that crack. And being very limited in airflow it's never going to dry. Sealing in moisture for years seems BAD.
In theory, I'm okay with the idea of taking this apart and rebuilding it (again, I've no idea what's likely to be back there, and am assuming it's just several sheets of marble held together with sealant). I also accept that could be over my head, or not needed. Is this safe to just seal over, or reasonably straightforward to take apart and rebuild? What's the best method of repair?
Some additional pictures in case they help.