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ADU JURISDICTION GUIDE

SAN MATEO COUNTY

Fees and Regulation (May 2022)

ADU-Allowed Zones

  • Bay Side: All R Zones are allowed except for R-3
  • Coast Side  R-1

ADU Size Limitations

Floor Area: Maximum of 1,200 Square Feet. No minimum.

ADU Building Height

26 Feet Maximum

Minimum Lot Size

5,000 square feet

Setbacks Requirement

Must be 5 feet on all sides unless any portion of ADU is in front of the primary dwelling unit, then normal setback laws apply. For garage or other accessory structure conversions, however, the state law applies.

Parking Space Requirements

  • For ADU Units with 1-2 Bedrooms, one parking space is required.
  • For ADU Units with 3 or more Bedrooms, two parking spaces are required.

*Unless state exemptions are met like when the ADU is built within a half a mile near public transportation, located in historic districts, placed within one block of car-sharing locations, or established in residential areas with their own parking permit regulations.

  • Tandem Parking and Setback Parking are allowed.
  • Permeable Paving is mandatory.

Owner Occupancy Requirement

None

Other Regulations

  • ADU must comply with California Building Code fire safety requirements. If the primary dwelling has sprinklers, the ADU must have sprinklers.
  •  There are no design requirements, unless the ADU is located in the Coastal Zone, in which case the ADU must be similar in shape, materials and style to the primary dwelling.
  • Tree removals may require a permit per the Heritage Tree Ordinance.
  •  Daylight plane and floor area ratio (FAR) requirements may apply.
  • No additional parking is required for garage conversions and replacement parking can be uncovered.
  • Only one ADU per property is allowed.
  • ADUs are only allowed on single family and duplex sites.
  • ADUs must conform to all development standards in the zoning district in which they are

ADU Permit Process

Average Time for ADU Plan Sets Approval

  • Initial Review: 30-60 Days
  • Permits Process: 30-60 days
  • Overall Avg. TIme: 60-120 Days

ADU Permit Fee

  • $450 for First Two Plan Reviews 
  • $150 for Each Subsequent Reviews
  • $500 Application Building Fee
  • $7 per sq. ft. General Permit Rate
  • $150-$300 Site Nominal Fees (Electrical, Mechanical, Coast-side Fire, Sanitary)
  • $150-200 Document storage (2% of all Planning/Building Fees)
  • $100 Address Request

Impact Fees

A local agency, special district, or water corporation shall not impose any impact fee upon the development of an accessory dwelling unit less than 750 square feet. Any impact fees charged for an accessory dwelling unit of 750 square feet or more shall be charged proportionately in relation to the square footage of the primary dwelling unit.

Source: AB-68 Land use: accessory dwelling units

Water/Sewer Line Connection Fee

None as long as ADU is under 750 square feet. 

*For an ADU that is separate from an existing structure, the City will require payment of a connection fee or capacity charge that is proportionate to the ADU’s burden.

Estimated Mavericks Permit Fees

  • Maverick 392: $2,744
  • Maverick 504: $3,528
  • Maverick 748:  $5,236

Resources

Contact Directory

San Mateo Planning Department 

San Mateo Building Department

Granada Sanitary District

Coastside County Water District

Coastside Fire Protection District

We hope this quick reference guide helps you out in your ADU project. Part of our service if you build with us is the full service of our in-house permit technician who handle the processing of your permit on your behalf with no mark-ups. 

If you’re interested in building with ADU.Works, please don’t hesitate to book a consultation with us or give us a quick call through our number +1 (650) 227 4810. We’ll gladly discuss the specifications of your permit processing and accommodate any questions you may have. Our team looks forward to hearing from you.

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