Windsor · Building on your lot

Lot splits under SB 9 in Windsor

Windsor's own rules on lot splits under SB 9, with the code text for every value.

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

What Windsor's code says

Windsor code What Windsor's code adds
How the lot may be divided	Each new lot must be 40% of the original lot's area. Applies: Urban lot splits into no more than 2 lots. § 17.94.100 · code text Each lot shall be forty (40) percent of the lot area of the lot proposed to be subdivided.
Unit size	At most 1,200 square feet. Applies: Each new primary unit. § 17.94.110 · code text The maximum size of each new primary unit is limited to one thousand two hundred (1,200) square feet. At most 1,200 square feet each. Applies: Each unit when an existing single-unit home is converted to a duplex. § 17.94.110 · code text When an existing single-unit dwelling is converted to a duplex, each of the resulting units shall not exceed one thousand two hundred (1,200) square feet.
Minimum new lot size	Each new lot must be at least 1,200 square feet. § 17.94.100 · code text Each newly created lot shall be a minimum of one thousand two hundred (1,200) square feet.
Setbacks	4 feet. Applies: Interior side setback. § 17.94.110 · code text 2. Interior side. Four (4) feet. 4 feet. Applies: Rear setback. § 17.94.110 · code text 4. Rear. Four (4) feet. 20 feet. Applies: Front setback. § 17.94.110 · code text 1. Front. Twenty (20) feet. 10 feet. Applies: Street-side setback. § 17.94.110 · code text 3. Street side. Ten (10) feet.
Standards	At most 1 story and 18 feet in the zone's required rear setback; 2 stories and 35 feet outside it. Applies: Height depends on location relative to the zone's required setback. § 17.94.110 · code text The maximum height is limited to one (1) story and eighteen (18) feet when located within the rear setback required by the underlying zoning district or two (2) stories and thirty-five (35) feet when located outside of the setback required by the underlying zoning district. Both lots need at least 40 feet of frontage on a public street. Applies: Urban lot split lots with public-street frontage. § 17.94.100 · code text A minimum of forty (40) feet of lot frontage on a public street is required for both parcels. The access easement must be at least 20 feet wide for its full length. Applies: Where 40 feet of street frontage is not provided; no structures or parking in the corridor. § 17.94.100 · code text Access shall be provided by an easement for ingress and egress and emergency vehicle access that is a minimum of twenty (20) feet in width for the entire length of the corridor. The access corridor must be at least 20 feet wide for its full length. Applies: Flag lots without 40 feet of street frontage; no buildings or parking in the corridor. § 17.94.100 · code text Access shall be provided by an access corridor that is a minimum of tewnty (20) feet in width for the entire length of the corridor. Lots must be at least 45 feet deep. § 17.94.100 · code text The minimum parcel depth shall be forty-five (45) feet. Lots must be at least 40 feet wide. § 17.94.100 · code text The minimum parcel width shall be forty (40) feet. At least 6 feet between the main home and all detached accessory structures. Applies: Structure separation, including units, garages and accessory structures. § 17.94.110 · code text Structures shall be separated by a minimum of six (6) feet between the primary dwelling unit and all detached accessory structures on the site, including all residential units, garages, and accessory structures. At least 200 square feet of continuous private open space, at least 10 feet in each direction. Applies: Each new primary home. § 17.94.110 · code text Each new primary dwelling unit shall provide a minimum of two hundred (200) square feet of continuous private open space, with minimum interior dimensions of ten (10) feet.
Parking	1 off-street parking space. Applies: Each new primary home. § 17.94.110 · code text One (1) off-street parking space shall be required for each new primary dwelling unit, unless the location of the lot complies with one (1) of the following. No off-street parking is required. Applies: Lots within ½ mile walking distance of a high-quality transit corridor or major transit stop. § 17.94.110 · code text The parcel is located within one-half (½) mile walking distance of a high-quality transit corridor as defined in Section 21155 of the California Public Resources Code or a major transit stop as defined in Section 21064.3 of the California Public Resources Code. No off-street parking is required. Applies: Lots within 1 block of a car-share location. § 17.94.110 · code text The lot is located within one (1) block of a car-share vehicle location.

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Frequently asked questions

Can I split my lot under SB 9 in Windsor?

Windsor's code: Each new lot must be at least 1,200 square feet. (§ 17.94.100); At most 1,200 square feet. (Each new primary unit.) (§ 17.94.110).

General information, not legal advice.

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Windsor Municipal Code — full text