California Existing Building Code (CEBC)

The California Existing Building Code (CEBC) is Part 10 of the California Building Standards Code (Title 24, California Code of Regulations). It provides the rules for repair, alteration, addition, relocation, and change of occupancy of existing buildings, so that work on an older structure does not have to meet every requirement of new construction. The CEBC is based on the International Existing Building Code (IEBC) with California-specific amendments adopted by state agencies such as HCD and DSA.

The 2025 California Existing Building Code is the current edition, effective January 1, 2026 (based on the 2024 IEBC), replacing the 2022 CEBC. Because the CEBC offers three different compliance paths and local jurisdictions may add amendments — especially for seismic retrofit — the requirements for your project depend on the scope of work and the edition your city or county has adopted. That reconciliation is exactly what GoCodebook does for you.

The CEBC applies whenever you do work on an existing building rather than build new: repairs (restoring damage), alterations (renovations and tenant improvements, classified as Level 1, 2 or 3 by how much of the building is reconfigured), additions, relocations, and change of occupancy (for example converting an office to housing). It scales the code requirements to the extent of the work, so minor repairs are not forced to trigger full code upgrades.

The CEBC is the home of adaptive reuse projects — converting warehouses to lofts, offices to apartments, or retail to community space — and it sets when a change in use triggers upgrades to structural, fire, accessibility and egress systems. It also coordinates with the California Building Code (CBC, Part 2), which still governs new portions, and with the California Historical Building Code (CHBC, Part 8) for qualified historic structures.

The CEBC lets a designer choose among three compliance methods. The prescriptive method treats most alterations like new construction under the CBC and is the simplest to document for small projects. The work-area method ties requirements to the percentage of the building affected, using alteration Levels 1, 2 and 3 so that larger projects pick up more upgrades. The performance method scores the building against fire-safety and other criteria, giving the most flexibility for complex existing structures.

Choosing the right path can be the difference between a feasible renovation and an impossible one, because each method triggers different accessibility, egress and fire-rating obligations. You can ask GoCodebook which method best fits your scope, or compare the CEBC against the CBC for the new portions of your job. See where coverage is deepest.

A major reason the CEBC matters in California is seismic safety. Alterations, additions and a change of occupancy can trigger structural and seismic-retrofit requirements, often evaluated under ASCE 41, and a renovation generally may not reduce a building's existing lateral (seismic) resistance. The CEBC includes guidance for the seismic evaluation and retrofit of existing buildings that local mandatory-retrofit ordinances build on.

Cities and counties frequently amend the CEBC and adopt their own retrofit ordinances — for soft-story, unreinforced-masonry (URM) and non-ductile concrete buildings — so the controlling rule for one address can differ from a neighboring jurisdiction. GoCodebook identifies the adopted edition and local amendments for your address and returns the governing CEBC provision with a citation so you can verify the original language quickly.

California's adopted codes — including the California Existing Building Code (CEBC) — 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.