San Mateo County
San Carlos ADU rules
San Carlos has an official local rule record in this scrape. Provider research is grouped at the San Mateo County level.
Local rule facts
Min/max ADU size
One bedroom or less: 850 square feet Two+ bedrooms: 1000 square feet Conversion of existing legally established detached structures: None JADU: 500 square feet *50% of main home floor area, unless under 800 square feet (state law allows an ADU up to 800 square feet on...
Height
Detached ADU: 18 + 2 feet to match the main building roof pitch Detached ADU with multistory, multifamily dwelling: 18 feet Detached ADU over or under detached garage: 20 feet Attached second story: determined by base zoning
Setbacks
First floor attached and detached: Side and rear – 4 feet, Front: setbacks determined by base zoning district The second floor is attached: determined by the base zoning district The second floor is attached on reversed corner lots: rear – 5 feet
Parking
JADUs: Any parking displaced by the construction of a JADU, including full or partial conversion of an existing garage, shall be replaced ADUs: One spot may be required (tandem allowed). No parking is required if ADU involves garage conversion or is: ½ mile walking...
Owner occupancy
JADUs: Required ADUs built recently (2020-2024): Not required *Where a lot contains both an accessory dwelling unit and a junior accessory dwelling unit, either the single-unit dwelling or the junior accessory dwelling unit shall be owner-occupied
Process
-at-a-Glance FAQs Floorplans Inspiration Glossary Guidebook + Exercises Pre-Designed Plans Process-at-a-Glance See the resources page Events About Contact Getting Started Learning the Rules Budgeting Design Permitting Construction Renting Getting Started Learning the...