ADU Feasibility & Yield Screener
California ADU law is ministerial statewide — nearly every single-family lot can add an ADU plus a JADU. Use this screener to rank active Silicon Valley listings by accessory-unit feasibility and find the best "stealth density" plays.
Lot & Coverage
We score lot size and how built-out it already is, so there is room for a detached unit after setbacks.
Yield Upside
High-feasibility lots support a detached ADU plus a JADU — adding rental income or multi-generational value.
Hazard-Aware
Fire, flood, and fault overlays lower the score and surface as blockers, so cost risk is visible up front.
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ADU Feasibility FAQ
What is an ADU and a JADU?
An Accessory Dwelling Unit (ADU) is a secondary home on a single-family lot — attached, detached, or a garage conversion. A Junior ADU (JADU) is up to 500 square feet created within the existing house. Under California law, essentially every single-family lot can add at least one ADU plus one JADU, ministerially.
How is the ADU feasibility score calculated?
The score (0-100) weighs lot size, how built-out the lot already is (existing living area as a coverage proxy, so there is room for a detached unit after setbacks), and any hazard or overlay blockers that raise construction cost. It is a screening heuristic, not a substitute for a local ADU ordinance check.
What is a "stealth density" play?
Stealth density means adding a detached ADU and a Junior ADU to a primary residence to boost yield and rental or multi-generational value — without triggering the fierce local pushback that formal SB 9 lot splits face on the Peninsula.
Do hazard zones affect ADU feasibility?
Yes. ADUs remain ministerial in most cases, but very high fire hazard zones, flood zones, and fault zones raise construction and insurance costs, so the screener lowers the feasibility score and flags those blockers rather than removing the listing outright.
Which markets does this ADU screener cover?
It surfaces active listings across San Mateo County and Santa Clara County, scored against ADU feasibility so you can focus on Silicon Valley lots with the strongest accessory-unit upside.