Local ADU Rules

Half Moon Bay

Last Updated August 29, 2024

ADU Contact:

Community Development Department – 650.726.8270

Standards
Details
Zones allowed

R-1, R-2, R-3, C-D, C-R, C-VS, C-G, PUD, and all mixed-use districts

Lot Restrictions

Lot coverage, floor area ratio, open space apply unless reducing the floor area of the ADU below 850 square feet, or the height below sixteen feet.

Minimum Lot Size

None

Min/Max ADU Size

Min: 150 sf,
Max one bedroom or less: 850 square feet,
Max two or more bedrooms: 1200 square feet

ADU Building Height

Attached two story: 28 feet
Attached one story: 20 feet
Detached: 16 feet if within rear yard setback; otherwise 20 feet.

Setbacks

Side and rear: 4 feet, Front: same as primary dwelling

Parking Requirements

JADUs: No parking required
ADUs: One spot may be required (tandem allowed). No parking required if:
½ mile walking distance from public transit, in a historic district, or one block from a car-share vehicle

on-street parking permits are required but not offered to ADU occupant

*Unless within parking area designated for coastal access

Owner Occupancy

Owner must live in the main dwelling or the ADU

Sample fees from recent permits

ADU 1 (2017, 609 sf, attached): $4,612 (does not include water fee)
ADU 2 (2017, 682 sf, detached): $4,512 (does not include water fee)
Charging impacts for ADUs 750 SF or greater per State law allowances.

Other requirements

One ADU or one JADU allowed per property. One JADU may be allowed with one ADU if the ADU does not exceed 850 square feet

Short-term rentals are not allowed.

New detached ADUs or additions require a Coastal Development Permit.

ADUs must comply with all requirements of the underlying zoning district.

If the existing single-family dwelling has fire sprinklers, sprinklers required

Generally siding, trim, roofing shall match those of the single-family dwelling in terms of color, material, roof pitch, etc.

No separate sewer or water connections required, although a separate water meter is required by the water district.

Proposals for tree removals must be approved through the City’s tree protection ordinance.

Process

If the ADU conforms to the zoning code (setbacks, height, etc.), the approval letter is drafted, notice is provided, and the ADU is approved. If requiring a variance, ADU might be processed through the planning commission. Making an appointment to meet with a planner in the initial stages of the project can help avoid challenges and is highly recommended.

Exceptions

None

Wondering what you can build?

Make sure you check out our Learning the Rules page for more step-by-step details
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