Lot splits under SB 9 in Walnut Creek: the local rules

Each rule below links to the section of the Walnut Creek Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.

What Walnut Creek's code says

Walnut Creek code What Walnut Creek's code adds
How the lot may be divided	No new lot may be smaller than 40% of the existing lot's area. Applies: Applies to each lot created by an urban lot split. § 10-1.1405 · code text No lot created by an urban lot split shall be smaller than forty percent (40%) of the area of the existing lot being subdivided.
Unit size	Inclusionary housing rules do not apply to units up to 850 square feet. Applies: Studio or 1-bedroom SB 9 units on net lots of 14,999 square feet or less. § 10-2.3.1508 · code text 14,999 square feet or less \| 850 square feet \| 1,000 square feet Inclusionary housing rules do not apply to units up to 900 square feet. Applies: Studio or 1-bedroom SB 9 units on net lots of 15,000 to 19,999 square feet. § 10-2.3.1508 · code text 15,000 to 19,999 square feet \| 900 square feet \| 1,000 square feet Inclusionary housing rules do not apply to units up to 950 square feet. Applies: Studio or 1-bedroom SB 9 units on net lots of 20,000 square feet or more. § 10-2.3.1508 · code text 20,000 square feet or more \| 950 square feet \| 1,000 square feet Inclusionary housing rules do not apply to units up to 1,000 square feet. Applies: SB 9 units with 2 or more bedrooms on net lots of 14,999 square feet or less. § 10-2.3.1508 · code text 14,999 square feet or less \| 850 square feet \| 1,000 square feet Inclusionary housing rules do not apply to units up to 1,000 square feet. Applies: SB 9 units with 2 or more bedrooms on net lots of 15,000 to 19,999 square feet. § 10-2.3.1508 · code text 15,000 to 19,999 square feet \| 900 square feet \| 1,000 square feet Inclusionary housing rules do not apply to units up to 1,000 square feet. Applies: SB 9 units with 2 or more bedrooms on net lots of 20,000 square feet or more. § 10-2.3.1508 · code text 20,000 square feet or more \| 950 square feet \| 1,000 square feet
Minimum new lot size	Each new lot must be at least 1,200 square feet. Applies: Applies to each lot created by an urban lot split. § 10-1.1405 · code text In addition, no lot created by an urban lot split shall be smaller than one thousand two hundred (1,200) square feet in area.
Standards	An urban lot split may create no more than 2 lots. Applies: Applies to urban lot splits. § 10-1.1405 · code text An urban lot split shall create no more than two (2) lots. Each new lot must have vehicle access to a public or private street. Applies: Applies to each lot from the urban lot split. § 10-1.1405 · code text Each lot resulting from the urban lot split shall have vehicular access to a public or private street. Rentals or leases must be at least 31 days. Applies: Applies to SB 9 units. § 10-2.3.1508 · code text The rental period or lease term for any SB 9 dwelling unit shall be a minimum of thirty-one (31) days. New utility connections must be underground. Applies: All new connections serving pre-SB 9 main homes or SB 9 units. § 10-2.3.1508 · code text All new utility connections serving pre-SB 9 primary dwellings or SB 9 dwelling units shall be installed underground.

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Frequently asked questions

Can I split my lot under SB 9 in Walnut Creek?

Walnut Creek's code: Each new lot must be at least 1,200 square feet. (Applies to each lot created by an urban lot split.) (§ 10-1.1405); Inclusionary housing rules do not apply to units up to 850 square feet. (Studio or 1-bedroom SB 9 units on net lots of 14,999 square feet or less.) (§ 10-2.3.1508).

Lot splits under SB 9 in Walnut Creek

What Walnut Creek's code says

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