Building codes & construction
California Residential Code (CRC)
Title 24, Part 2.5 — the IRC-based code for one- and two-family dwellings, townhouses up to three stories, and most ADUs. Simpler and cheaper than the CBC.
Definition
The California Residential Code (Title 24, Part 2.5) is the IRC-based code for detached one- and two-family dwellings, townhouses of up to three stories with independent means of egress, and their accessory structures — which is why most ADUs and JADUs are permitted under the CRC rather than the CBC (HCD's ADU Handbook walks through the mapping). It is largely prescriptive: conventional framing, bracing and span tables a plan checker can approve without a fully engineered design, plus residential fire sprinklers in new dwellings.
Why it matters in an underwrite
Whether a product type rides the CRC or the CBC is a real cost fork: prescriptive CRC construction avoids much of the engineering, rated-assembly and accessibility scope that CBC R-2 buildings carry. Small-lot townhouse and ADU strategies are largely CRC plays — three stories is the ceiling, and crossing it (or attaching units into an apartment configuration) moves the whole project into the CBC and reprices it.
Sources & related guides
See also
See the term in the law itself
Read the controlling text in the Code Library, or ask the AI how it applies to your project.
Last reviewed 2026-07-29. General information, not legal advice.