Lot splits under SB 9 in San Anselmo: the local rules

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

What San Anselmo's code says

San Anselmo code What San Anselmo's code adds
How the lot may be divided	Two lots of about equal area; neither smaller than 40% of the original lot. Applies: Urban lot splits in the R-1, R-1-H or R-1-C zones. § 10-4.304 · code text The parcel map divides an existing parcel to create no more than two (2) new parcels of approximately equal lot area provided that one (1) parcel shall not be smaller than forty (40%) percent of the lot area of the original parcel proposed for subdivision.
Minimum new lot size	Neither the new lot nor the original lot may be smaller than 1,200 square feet. Applies: Applies to the new lot and the original lot. § 10-4.304 · code text Neither the newly created lot nor the original lot shall be smaller than one thousand and two hundred (1,200) square feet.
Setbacks	4 feet from the side and rear lot lines. Applies: Applies to a newly created home. § 10-4.405 · code text A setback of four (4) feet from the side and rear lot lines is required for a newly created dwelling unit. No setback is required. Applies: Only for an existing home, or one rebuilt in the same place and to the same size. § 10-4.405 · code text no setback shall be required for an existing dwelling unit or a dwelling unit constructed in the same location and to the same dimensions as an existing dwelling unit.
Standards	Each new lot must have access to, provide access to, or border a right-of-way. Applies: Applies to each newly created lot. § 10-4.305 · code text Each newly created parcel shall have access to, provide access to, or adjoin a right-of-way. Town standards may not prevent 2 units on either new lot, or units of at least 800 square feet. Applies: Applies to urban lot splits and two-unit developments. § 10-4.305 · code text the Town shall not impose objective zoning standards, objective subdivision standards, or objective design review standards that would have the effect of physically precluding the construction of two (2) dwelling units on either of the newly created parcels or that would result in a dwelling unit size of less than eight hundred (800) square feet.

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Frequently asked questions

Can I split my lot under SB 9 in San Anselmo?

SB 9 splits in R-1 zones make 2 near-equal parcels, each at least 1,200 square feet and 40% of the original parcel.

Lot splits under SB 9 in San Anselmo

Key points

What San Anselmo's code says

Who this affects

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