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Would adding a small room onto a recently (within less than 2 years) be considered as adding onto an existing building, and thus have to be designed per the 'Existing' Building Codes, or just the 'regular' code.
It hasn't been enough since the publication of the 2015 IBC when they deleted Chapter 34, effectively removing all requirements for existing buildings.
Note: Provisions of former Chapter 34, Existing Structures, are now located in Part 10, California Existing Building Code. This change is in keeping with modifications to the 2015 editions of the International Building Code and International Existing Build- ing Code by the International Code Council. See Section 101.4.7.
That's what I was trying to point out in regard to your post about "one code" not being enough--what could have been retained in one code is now contained in two codes.
Wish we followed NFPA Guidelines in this aspect - IF the building was built under the same building code as the proposed addition; it would still be considered a "new" building.