More Installation FAILS - folding door “floating” sills

Just because a window company sells and installs doesn't mean they are competent! I can help you avoid this before you even contract a dealer as a luxury hurricane glazing consulting free from dealer and manufacturer biases.

And the builder said "oh we just fill that in with mortar after"...

Yes folding doors are top supported but there is no way to properly waterproof this will condition it WILL leak, not if but when!

It also isn't structurally anchored by any engineering standard.

And cement in direct contact with aluminum especially in a saltwater exposure like this is going to cause corrosion.

You should be including installation best practices requirements in your contracts and enforcing them, I can help write them and review your dealer proposals.