Atherton ADU size limits
Detached and Attached: 1200 square feet if setback requirements met Attached: less than 50% of primary dwelling, no more than 1200 feet JADU: 500 square feet
San Mateo County
Atherton ADU rules
Atherton has an official local rule record in this scrape. Provider research is grouped at the San Mateo County level.
Direct answer
Can I build an ADU in Atherton?
Athertonhas an official local ADU rule record in this directory. Start with the city's size, height, setback, parking, and owner occupancy standards below, then confirm lot-specific limits with the official source before hiring design or construction help.
Atherton ADU rule guide
Atherton height and setbacks
Attached: height of main dwelling Detached: 16-18 feet Attached: <800 sqft ADUs: Up to 4 feet. Same as primary dwelling in R-1A and R-1B. >800 sqft ADUs: Can encroach 20% into the required side and rear setbacks. Detached: ADUs 800-1,200 sqft: 120 feet from front property line or 30 feet behind front line of the main residence, whichever is less. 10 feet side yard and rear. ADUs <800...
Atherton parking and owner occupancy
JADUs: No parking required ADUs: One spot may be required (tandem allowed). No parking required if: a. ADU is located within one-half mile of public transit. b. ADU is part of a proposed or existing primary residence or an existing accessory structure. c. On-street parking permits are required but not offered to the occupant of the ADU. d. A car share vehicle is located within one block...
How Atherton ADU permitting works
-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 Rules Budgeting Design Permitting Construction Renting Home » Local Rules » Atherton Local ADU Rules Atherton Last...
Local rule facts
Min/max ADU size
Detached and Attached: 1200 square feet if setback requirements met Attached: less than 50% of primary dwelling, no more than 1200 feet JADU: 500 square feet
Height
Attached: height of main dwelling Detached: 16-18 feet
Setbacks
Attached: <800 sqft ADUs: Up to 4 feet. Same as primary dwelling in R-1A and R-1B. >800 sqft ADUs: Can encroach 20% into the required side and rear setbacks. Detached: ADUs 800-1,200 sqft: 120 feet from front property line or 30 feet behind front line of the main...
Parking
JADUs: No parking required ADUs: One spot may be required (tandem allowed). No parking required if: a. ADU is located within one-half mile of public transit. b. ADU is part of a proposed or existing primary residence or an existing accessory structure. c. On-street...
Owner occupancy
1. ADUs and JADUs Permitted Before January 1, 2020. The owner-occupancy requirements applicable to the ADU or JADU at the time of its permitting shall apply. 2. ADUs and JADUs Permitted Between January 1, 2020, and January 1, 2025. No owner-occupancy requirements shall...
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...