If your state/county/municipality has adopted International Building Code then they most likely adopted NFPA guidelines. I say most likely because they can choose which parts to adopt. IBC refers to NFPA so in most instances it's the code.
The guidelines for storage containers are available online. SAAMI has sections of NFPA in their handbooks. The short version is up to 20# can be stored in their original bottles. 20-50# must be in a wood container w/ walls at least 1" thick. I found an older version of the NFPA book in my garage last week so I will look to see if there are more construction details. It's 50#s per residence, don't know if this is separate structures or total per address. Powder and primers are to be stored separately and the limit on primers is 10k. Everyone goes over that limit.