Note that I did not say that I am in compliance myself

I have seven 20 lb tanks stored in my garage and I usually run two burners in my garage when I brew. I really should find a way to store them outside. It's stupid not to.
Here's the link to the National Fire Protection Association:
http://www.nfpa.org/
The site is not easy to navigate and you must register to view the documents. I'm not exactly sure how the regulations are implemented. I think that state and municipal regulations are based on the NFPA codes, but not sure if the codes themselves are the law. It might be easier to check your particular state fire codes.