Atherton ADU topic page
Atherton ADU Rules
Start with the official local ADU rules, then confirm lot-specific limits before requesting provider quotes.
Short answer
Start with the official local ADU rules, then confirm lot-specific limits before requesting provider quotes.
Source requirement: Official city or county rule source parsed and cited.
Local rule evidence
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
Setbacks and parking
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...