Accessory Dwelling Units are the single best way to add value, income, or multigenerational space to a Bay Area property — and California's pro-ADU laws have made them faster to approve than almost any other project. A well-built ADU can rent for thousands a month or keep family close with independence.
ODL Construction builds the full range: detached new-construction ADUs, attached units, garage and basement conversions, and junior ADUs (JADUs). We handle California ADU law, local ordinances, Title 24, utilities, and the 60-day ministerial review the state now mandates for compliant designs.
Because lot, setback, and utility realities vary enormously across the Bay — a Fremont lot plays by different rules than a Palo Alto Eichler parcel — we start with a free feasibility assessment so you know what's buildable and what it pencils out to before you commit.
What's included
- Detached new-construction ADUs
- Attached ADUs
- Garage and basement conversions
- Junior ADUs (JADUs)
- Feasibility, lot, and setback analysis
- California ADU law and local ordinance compliance
- Utility connections and Title 24 energy compliance
- Full permitting and inspections
Our process
- 1
Free feasibility assessment
We evaluate your lot, setbacks, utilities, and the most cost-effective ADU type — detached, attached, or conversion — and what it can realistically rent for.
- 2
Design & fixed proposal
We design the unit to California ADU law and your local ordinance, then deliver a fixed-scope proposal.
- 3
Permits (ministerial review)
We submit a compliant design for the state-mandated 60-day ministerial review and handle Title 24, utility, and any school-fee requirements.
- 4
Build
Foundation through finish for detached units, or full conversion for garages — managed on a clear schedule.
- 5
Final inspection & handoff
We pass final inspection, connect utilities, and hand you a rent-ready, code-compliant unit.
ADU Construction cost in the Bay Area
Garage conversion ADU
Converting an existing garage — the most cost-effective ADU type.
$150,000 – $250,000
Detached ADU (new construction)
Ground-up detached unit, roughly $400–$600/sq ft depending on size and finish.
$250,000 – $450,000
Larger / premium detached ADU
1,000+ sq ft, higher finishes, complex site or utility work.
$450,000 – $650,000+
Typical Bay Area ranges, not a quote. ADU cost is driven most by type (conversion vs. detached), size, site access, and utility connections. We give you a fixed proposal after a free feasibility visit.
Remodel now, pay monthly. Ask about flexible financing options for your project.
Financing options →Timeline
Garage conversions often finish in 3–4 months; detached ADUs typically run 6–9 months including the 60-day permit review.
Permits & code
California law now requires ministerial (non-discretionary) approval of code-compliant ADUs within 60 days, limits owner-occupancy and parking requirements, and caps many fees. We design to those state rules plus your city's ordinance so approval is fast and predictable.
Key things to consider
- Conversion vs. detached is the biggest cost and timeline decision.
- Detached units add the most value and flexibility but cost more.
- Utility connections (sewer, water, electrical panel capacity) can drive cost — we check early.
- Rental math: many Bay Area ADUs return strong monthly income; we'll help you assess it.
