2002 NEC 450.42 Walls, Roofs, and Floors.
The walls and roofs of vaults shall be constructed of materials that have adequate structural strength for the conditions with a minimum fire resistance of 3 hours. The floors of vaults in contact with the earth shall be of concrete that is not less than 100 mm (4 in.) thick, but where the vault is constructed with a vacant space or other stories below it, the floor shall have adequate structural strength for the load imposed thereon and a minimum fire resistance of 3 hours. For the purposes of this section, studs and wallboard construction shall not be acceptable.
I don?t think this set of specifications constitutes a definition of ?vault.? I think the logic flows in the opposite direction. If you need to have a vault (450.21(C) is one article that requires one), then the article you quoted tells us how to build one. However, I can build a room that meets those specifications, and use it as a wine cellar, and it will not be, by definition, a ?vault.?Originally posted by websparky:If a "room" meets these specifications, it's a "vault".
Then please allow me to state my opinion: I believe we should put the word ?vault? on our list of ?words we know but do not use often.? During conversations among friends, the term has been loosely applied to any room with a heavy door or any box-shaped space that is buried under dirt. But when we are bidding, designing, building, or inspecting, we should be careful to avoid ?Conversational English.? We should say ?vault? only when the technical requirements of the project explicitly demand the use of that word. And we should acknowledge that this type of project is rare.Originally posted by websparky:Personally, I would rather give some advice or opinion that could help, rather than just saying the code does not answer the question and then comment on the inadequateness of the code.