Building codes & construction
Change of occupancy
Reclassifying a building to a different occupancy group — like office (B) to apartments (R-2) — which triggers compliance with the new use's code requirements.
Definition
A change of occupancy is the reclassification of a building or space to a different occupancy group or use — the office-to-residential conversion (Group B to R-2) being the canonical example — whether or not construction accompanies it. Under the California Existing Building Code, the building must then meet the requirements the code applies to the new occupancy: fire protection and sprinklers, egress, accessibility, energy provisions for altered systems, and structural upgrades where the change increases hazard or risk. The permit trail matters too — a use that was never legally established is a change of occupancy waiting to be discovered at plan check.
Why it matters in an underwrite
In adaptive-reuse underwriting the change-of-occupancy analysis effectively is the pro forma: an office floor plate converting to R-2 may need sprinklers, added egress, Chapter 11A accessibility and unit separations before a single kitchen is priced. Commission a code study before the LOI, because the delta between "cosmetic conversion" and what the CEBC actually requires is routinely the largest unpriced number in the deal.
Sources & related guides
See also
See the term in the law itself
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Last reviewed 2026-07-29. General information, not legal advice.