Hmmm vaults. I like them. Particularly on a renovation project such as a postwar bungalow with a terrible layout and low ceiling height throughout. Adding a vaulted ceiling is the opposite of a lipstick and mascara job on a tired structure. It represents an investment by the builder into a costly structural component that opens up and radically alters a space. As far as cost we can get into to bills, but so far my math suggests it is worth it. We will know more in a month or so.
This will really add some volume to an old house and eliminate the need for load bearing partition walls. Given lumber prices today this cost a lot more than it should be was overall reasonable to assemble.