Quoted:

That is all very true, but guys who don't need that type of protection aren't getting bids for it.  Although what you say makes a lot of sense for the average guy with average stuff, I suspect that is not who the OP is.

It's like a professional NASCAR driver asking for seat recommendations and all of the riced out Honda Civic owners post what they use from Amazon.   The "why won't 8 inches of concrete suffice" is answered by the OP's very topic.  8 inches in typical house foundation form is not comparable in any way to a Class 3 UL rated vault construction.  We have worked on vaults and panic rooms in residential construction where our portion of the work was well into the mid six figures.  The owners weren't doing that work to thwart smash and grab burglars or protect a thousand dollars worth of jewelry.  These types have their reasons (which I wouldn't expect them to fully divulge on a public message board), and suggesting they don't need these levels of security without having any knowledge of what their intended use may be is doing them a great disservice.  You'll notice several comments along the lines of "seems overbuilt", but not a single comment from the OP stating exactly what he's using it for.  So there's no way to know if it's overbuilt.  It may be underbuilt for his use.

That said, those giving the bids should have been offering proper guidance.  If the OP asked for a bid on a Class 3 unit from a professional security company, that company should have had a conversation with him regarding the use.  Should his request have been entirely overkill that company should have offered proper guidance to a suitable solution.  Should the customer insist on the overkill that is fine.  But should a half price alternative that would suit the needs be available, the customer should be made aware.

The OP states he is providing a door, but hasn't stated what that is.  Were I the contractor contacted, that would have been my first question as the design of the vault should be commensurate with that of the door.

you also have to consider that the folks with 6 & 7 figure collections they're trying to protect aren't asking about vault advice on a gun forum either  

Quoted:
Just curious why y'all went with poured concrete instead of the pre-fab units with higher psi, and lower install time?  Don't see why those couldn't be custom made with the rebar and a way to lock them together.  I'm not a foreman, so be gentle.

Quoted:

Sure they do.  You'd be surprised who hangs out in these forums.  

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