Los Altos Hills · Building on your lot

Lot splits under SB 9 in Los Altos Hills

Los Altos Hills's own rules on lot splits under sb 9, with the code text for every value, and the state law underneath.

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

What Los Altos Hills's code says

Los Altos Hills code What Los Altos Hills's code adds
How the lot may be divided	2 lots of about equal area; neither smaller than 40% of the original lot's area. Applies: SB 9 lot splits. § 10-1.1504 · code text one parcel shall not be smaller than 40% of the lot area of the original parcel proposed for subdivision.
Unit size	At most 900 square feet. Applies: A standard SB 9 unit. § 10-1.1505 · code text The maximum size and development area for one SB 9 unit shall be 900 square feet with a maximum height of 16 feet. At most 900 square feet each. Applies: Up to 2 SB 9 units on a vacant SB 9 lot with a maximum floor area under 1,800 square feet. § 10-1.1505 · code text For any vacant SB 9 lot with an MFA of less than 1,800 square feet, the parcel shall be allowed to construct up to two SB units with a maximum size of 900 square feet and a height of 16 feet each. At most 2,000 square feet. Applies: Lots with a lot unit factor of 0.5 or less; incentive if the unit meets 40-foot front and 30-foot side/rear setbacks and easements are dedicated. § 10-1.1505 · code text For parcels with a lot unit factor (LUF) as defined under Section 10-1.202 less than or equal to 0.5, the maximum size of one SB 9 unit shall not exceed 2,000 square feet. At most 3,000 square feet. Applies: Lots with a lot unit factor over 0.5; incentive if the unit meets 40-foot front and 30-foot side/rear setbacks and easements are dedicated. § 10-1.1505 · code text For parcels with a lot unit factor (LUF) as defined under Section 10-1.202 greater than 0.5, the maximum size of one SB 9 unit shall not exceed 3,000 square feet. Up to 2,000 square feet or the lot's maximum floor area minus 900 square feet, whichever is less. Applies: 1 SB 9 unit, lot unit factor 0.5 or less; incentive needs 40-foot front and 30-foot side/rear setbacks and dedicated easements. § 10-1.1505 · code text For SB 9 lots with a lot unit factor (LUF) as defined under Section 10-1.202 less than or equal to 0.5, up to 2,000 square feet or the maximum floor area of the lot minus 900 square feet, whichever is less, shall be available for the development of one SB 9 unit. Up to 3,000 square feet or the lot's maximum floor area minus 900 square feet, whichever is less. Applies: 1 SB 9 unit, lot unit factor over 0.5; incentive needs 40-foot front and 30-foot side/rear setbacks and dedicated easements. § 10-1.1505 · code text For SB 9 lots with a lot unit factor (LUF) as defined under Section 10-1.202 greater than 0.5, up to 3,000 square feet or the maximum floor area of the lot minus 900 square feet, whichever is less, shall be available for the development of one SB 9 unit.
Minimum new lot size	Each new lot must be at least 1,200 square feet. § 10-1.1504 · code text In no instance shall any resulting parcel be smaller than 1,200 square feet in area.
Setbacks	At least 40 feet in front; at least 4 feet on the sides and rear. Applies: New SB 9 homes; the front is measured from roof eaves and other permanent wall features. § 10-1.1505 · code text The minimum front yard setback for any new SB 9 dwelling unit shall be 40 feet measured from any point of the architecture extrusions, including roof eaves and permanent wall features to the front parcel line or a public or private road right-of-way and four feet from the side and rear parcel lines. No setback is required. Applies: A home built in the same place and to the same size as an existing structure. § 10-1.1505 · code text Notwithstanding the foregoing, no setback shall be required for a dwelling unit proposed pursuant to this article that is constructed in the same location and to the same dimensions as an existing structure on the parcel in accordance with Section 10-1.1504(j). 40-foot front and 30-foot side and rear setbacks. Applies: Outdoor patios, covered patios, decks and other hardscape, except walkways. § 10-1.1505 · code text In addition, all outdoor patios, covered patios, decks, and other hardscape, except walkways as defined in Section 10-1.202, shall meet the standard 40 foot front and 30 foot side and rear setbacks as set forth under Section 10-1.505.
Standards	At most 16 feet tall. Applies: SB 9 units, including when a development incentive applies. § 10-1.1505 · code text The maximum size and development area for one SB 9 unit shall be 900 square feet with a maximum height of 16 feet. New lots can be at most 3 times as deep as they are wide (3:1). Applies: SB 9 lot splits; waived if it would prevent an otherwise allowed split. § 10-1.1504 · code text Resulting lots shall have a maximum depth to width ratio of three to one (3:1). A 20-foot-wide panhandle or access easement is required. Applies: New lots without direct frontage on a public or private road. § 10-1.1504 · code text A 20 foot wide panhandle (for a flag lot) or an ingress/egress easement shall be provided for all new parcels that do not have direct frontage on a public or private road. No more than 1 driveway cut per lot. Applies: New SB 9 lots. § 10-1.1504 · code text No more than one driveway cut is permitted for each parcel. No structures on areas with slopes steeper than 30%. Applies: SB 9 units. § 10-1.1505 · code text Areas with slopes greater than 30%. Detached units must be at least 10 feet apart, including eaves. Applies: Detached SB 9 units. § 10-1.1506 · code text Detached units shall maintain no less than 10 foot separation, inclusive of eaves, measured from the exterior walls. Windows can cover no more than 33% of any facade. Applies: SB 9 units. § 10-1.1506 · code text Windows shall not occupy more than 33% of any façade of an SB 9 unit. A solid 1-hour fire wall; no internal access between units; a deed restriction keeps a duplex as 2 separate units. Applies: SB 9 units and other homes on the lot. § 10-1.1506 · code text A solid (no openings) one-hour fire wall shall be required between an SB 9 unit, the primary dwelling, an ADU, or any two units configured as a duplex on a parcel. No internal accesses are permitted between the SB 9 units and other dwelling units.
Parking	1 on-site parking space. Applies: Per SB 9 unit. § 10-1.1505 · code text One on-site parking space is required per SB 9 unit as follows: No parking is required. Applies: Lots within ½ mile walking distance of a high-quality transit corridor or major transit stop. § 10-1.1505 · code text The parcel is located within one-half mile walking distance of either a high-quality transit corridor, as defined in subdivision (b) of Section 21155 of the Public Resources Code, or a major transit stop, as defined in Section 21064.3 of the Public Resources Code. No parking is required. Applies: A car-share vehicle is within 1 block of the lot. § 10-1.1505 · code text There is a car share vehicle located within one block of the parcel.

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Frequently asked questions

Can I split my lot under SB 9 in Los Altos Hills?

Los Altos Hills's code: 2 lots of about equal area; neither smaller than 40% of the original lot's area. (SB 9 lot splits.) (§ 10-1.1504); At most 900 square feet. (A standard SB 9 unit.) (§ 10-1.1505).

General information, not legal advice.

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