New Construction – San Diego

What Does San Diego’s New 2025 Building Code Mean for Your Custom Home Build in 2026?

San Diego adopted the 2025 California Building Standards Code, and the statewide edition took effect on January 1, 2026. If you are planning a new custom home, here is what the updated structural, site and safety rules actually change — and which pieces are still being finalized at the local level.

The short answer: what changed, and when

California updates its Building Standards Code on a three-year cycle. The 2025 edition was published July 1, 2025, and became effective statewide on January 1, 2026, for projects whose building permit applications are submitted on or after that date. That one fact is the headline: if you submit a new-construction application for a custom home in San Diego from this point forward, your project is reviewed against the 2025 code, not the 2022 edition.

What is less widely understood is that San Diego layers its own local amendments on top of the state code — and those local amendments are a separate, slower process. The city’s Development Services Department has said the local amendments to the 2025 code are expected to take effect only after the City Council approves implementing ordinances, with action anticipated in February or March 2026. Until then, the statewide 2025 code applies on its own in San Diego for the areas the local amendments eventually touch.

Why San Diego’s local rules take longer than the state code

Every California city and county is allowed to adopt local amendments to the state code for its own climate, geology, and topography — that is exactly how San Diego’s wind, seismic, and termite provisions exist in the first place. But local amendments go through their own public process: Technical Advisory Committee review, a City Council hearing, and filing with the state, on top of the state’s own triennial deadline.

For the 2025 cycle, San Diego’s technical advisory review began in October 2025, with Council action expected in February or March 2026. The city has published a fact sheet, an adoption matrix, and a line-by-line list of proposed amendments to the Land Development Code, Municipal Code Chapters 12 and 14, and the Municipal Code’s wildfire chapter, but as of this writing the ordinances have not been finalized. If you are deep into design on a new custom home, this is the single most important thing to track with your design-build team or your plan checker: the rules most relevant to your site — geotechnical, structural, and fire-related — are the ones most likely to shift slightly before final adoption.

Structural and site rules for a new home build

San Diego’s local amendments to the 2025 California Residential Code carry forward the city’s own structural design criteria, which every new single-family home must be engineered to meet. These numbers do not change often, but a design-build team should confirm them against the current adopted table before finalizing structural plans.

The same update also adds structural observation to the required statement of special inspections for qualifying projects, meaning an engineer of record signs off on specific structural stages during construction — not only at plan check. For sites in a mapped flood hazard area, any grading, excavation, or fill work now requires a civil engineer’s analysis showing the work will not raise the base flood elevation of the floodway, under the updated local flood provisions.

The new geotechnical investigation waiver

Historically, San Diego’s geotechnical investigation rules for residential sites dated back to the 1980s. The 2025 local amendments update Municipal Code Section 145.1803 with a narrower, more specific waiver.

Under the proposed update, a standalone single-family dwelling may qualify for a waiver from investigating a specific geologic hazard — not a full waiver from geotechnical review — if it meets conditions including:

• The site is not within an Alquist-Priolo earthquake fault zone or certain other hazard categories.
• The building is generally three stories or less.
• The project is not part of a larger development of four or more dwelling units.
• For an addition to an existing home, the added work is under 50% of the building’s replacement value and under 50% of its existing floor area, and the site is not in Hazard Category 21.

A waiver on one specific hazard does not eliminate the need for a geotechnical report addressing foundation design and other site conditions. Every new custom home still needs a soils-based foundation design; this update narrows which specific hazard studies can be skipped, and for which homes.

New rules for pools, garage doors and roofing

Several of the local amendments touch features that are common on a new custom-home build, even though they are not structural in nature.

The pool provisions matter most for a custom home with a backyard pool planned from day one: the Building Official must inspect the required drowning-prevention features before final approval, so they need to be designed in, not added after the fact. The garage door backup requirement is a small line-item cost on a new build, but it is easy to miss if a door opener gets selected late in construction.

Wildfire-hardening rules move to a new chapter

San Diego’s existing ignition-resistant construction standards — often called “home hardening” — are being relocated out of the building and residential codes and into a new Wildland-Urban Interface chapter of the Municipal Code, to align with the state’s own new WUI code. For homes in a mapped High or Very High Fire Hazard Severity Zone, the substance of the rules is largely the same, carried over with local additions: non-combustible gutters and downspouts that resist debris buildup, non-combustible drip-edge flashing, welded-corner vinyl window frames with metal reinforcement, and spark arresters on chimneys and flues.

For a new-construction project in one of these zones, this mainly changes where your plan checker looks for the requirement, not what the requirement asks of your design.