Chapter 9-20 — Residential Code

The 2025 California Residential Code, with necessary State amendments, including appendices BG and CI published by the California Building Standards Commission, 2525 Natomas Park Drive, Suite 130, Sacramento, CA 95833-2936, one copy of which is kept in the office of the Building Official, is adopted and referred to, and by this reference expressly incorporated and made a part of this chapter as though fully set forth herein, subject to the amendments set forth in this chapter. The 2025 California Residential Code shall be known, designated and referred to as the "California Residential Code."

The California Residential Code, as amended in this chapter, shall be known, designated and referred to as the "Residential Code" for the City of Walnut Creek.

(Ord. 2254, 11-18-2025, eff. 12-19-2025)

Division II of Chapter 1 of the California Residential Code is hereby deleted and replaced by Chapter 0.5 of this Title.

(Ord. 2254, 11-18-2025, eff. 12-19-2025)

Amend definition of "Substantial Improvement" in Section R202 to read as follows:

SUBSTANTIAL IMPROVEMENT. For the purposes of determining compliance with the flood provision of this code, any one or more or any combination of repair, reconstruction, rehabilitation, alteration, addition or other improvement of a building or structure taking place during a 3-year period, the cumulative cost of which equals or exceeds 50 percent of the market value of the structure before the improvement or repair is started. For each building or structure, the 3-year period begins on the date of the first permit issued for improvement or repair of that building or structure subsequent to 10/12/2000. If the structure has sustained substantial damage, any repairs are considered substantial improvement regardless of the actual repair work performed. The term does not, however, include either:

1. Any project for improvement of a building required to correct existing health, sanitary or safety code violations identified by the building official and that are the minimum necessary to assure safe living conditions.

2. Any alteration of a historic structure provided that the alteration will not preclude the structure's continued designation as a historic structure. For the purpose of this exclusion, a historic building shall be any of the following:

Designated as historic under a state or local historic preservation program that is approved by the Department of the Interior.

(Ord. 2254, 11-18-2025, eff. 12-19-2025)

Amend Section R306.2.1 to read as follows:

R306.2.1 Elevation requirements.

1. Buildings and structures in flood hazard areas, not including flood hazard areas designated as Coastal A Zones, shall have the lowest floors elevated to or above the base flood elevation plus 2 feet (610 mm), or the design flood elevation, whichever is higher.

2. In areas of shallow flooding (AO Zones), buildings and structures shall have the lowest floor (including basement) elevated to a height above the highest adjacent grade of not less than the depth number specified in feet (mm) on the FIRM plus 2 feet (610 mm), or not less than 5 feet (1524 mm), if a depth number is not specified.

3. Basement floors that are below grade on all sides shall be elevated to or above base flood elevation plus 2 feet (610 mm), or the design flood elevation, whichever is higher.

4. Garage and carport floors shall comply with one of the following:

They shall be at or above grade on not less than one side. Where a garage or carport is enclosed by walls, the garage or carport shall be used solely for parking, building access or storage.

5. Detached accessory structures and detached garages shall comply with one of the following:

Table R602.10.3(3) (Bracing Requirements Based on Seismic Design Category) of CRC Chapter 6 (Wall Construction) is amended as follows:

(1) The title of Table R602.10.3(3) is amended to read:

TABLE R602.10.3(3)i, j – BRACING REQUIREMENTS BASED ON SESIMIC DESIGN CATEGORY

(2) Footnotes "i" and "j" are added to Table R602.10.3(3), to read:

i. Methods PBS, HPS, SFB and CS-SFB are not permitted in Seismic Design Categories D0, D1, and D2.

j. Methods GB, DWB and PCP are not permitted in Seismic Design Categories D0, D1, and D2 where S1 is greater than or equal to 0.75.

(Ord. 2254, 11-18-2025, eff. 12-19-2025)