California Residential Code (CRC)

The California Residential Code (CRC) is Part 2.5 of the California Building Standards Code (Title 24, California Code of Regulations). It is the dedicated code for detached one- and two-family dwellings and townhouses not more than three stories above grade plane with a separate means of egress, plus their accessory structures. The CRC is based on the International Residential Code (IRC) — the 2025 CRC tracks the 2024 IRC — with California-specific amendments adopted by HCD and other state agencies.

The 2025 California Residential Code is the current edition, effective January 1, 2026, replacing the 2022 CRC. Because the code is adopted on a three-year cycle and cities and counties may add local amendments, the exact requirements for your house, deck or ADU depend on the edition your jurisdiction has adopted and any local changes — which is exactly what GoCodebook reconciles for you.

The CRC is a self-contained code that consolidates building, energy, mechanical, plumbing and electrical provisions for low-rise homes into one document. Core areas include building planning (light, ventilation, ceiling heights, room sizes), means of egress and emergency escape and rescue openings (egress windows), smoke and carbon monoxide alarms, stairs, ramps, handrails and guards, decks and their attachment, foundations and footings, wall and roof-ceiling framing, and fire-resistant construction in wildfire areas.

Many remodels, additions, decks, re-roofs and ADUs are evaluated against the CRC. Single-family homes in California also generally require automatic fire sprinklers (NFPA 13D) and increasingly solar PV under the Energy Code. See where GoCodebook coverage is deepest for residential questions.

Use the CRC when your project is a detached one- or two-family dwelling or a townhouse not more than three stories above grade plane with a separate means of egress, or an accessory structure to one of those. Once a building exceeds three stories, has more than two dwelling units, or changes to a non-residential use, it generally falls under the California Building Code (CBC, Part 2) instead. Apartment and condominium buildings are CBC, not CRC.

ADUs are usually regulated under the CRC because they are accessory to a one- or two-family dwelling. A common rule trips people up: an ADU typically only needs fire sprinklers if the primary dwelling is sprinklered. Mixing up CRC and CBC scope is one of the most frequent sources of plan-check corrections — GoCodebook tells you which code controls and cites the section.

The CRC is where homeowners and contractors find the everyday rules: emergency escape and rescue (egress) window sizing for sleeping rooms and basements, smoke alarm and carbon monoxide alarm placement (in each sleeping room, outside each sleeping area, and on every level), guard and handrail heights, stair riser and tread dimensions, and deck ledger attachment and footing requirements that have tightened in recent code cycles after deck-collapse failures.

A single residential project usually triggers more than the CRC. Larger ADUs, complex electrical work and solar often pull in the California Electrical Code (CEC, Part 3), while administrative questions about adopted editions and amendments are governed by the California Administrative Code (CAC, Part 1). Ask GoCodebook and get the controlling section with a citation.

California's adopted codes — including the California Residential Code (CRC) — are published under Title 24 and hosted on code libraries such as UpCodes (up.codes) and ICC Digital Codes from the International Code Council (ICC). Those let you read the text section by section.

GoCodebook goes further: instead of searching a code library, you ask a question and get the controlling provision for the edition and local amendments your jurisdiction adopted, with a citation to verify. See how GoCodebook compares to UpCodes and ICC.