Accessory Dwelling Units
ADUs in the Bay Area: Design, Permits & Construction
A backyard home can add $1,500–$4,500/month in rent and significant resale value. We design it, permit it, finance it, and build it — start to finish.
California's ADU laws are the single biggest opportunity for Bay Area homeowners in a generation. State law now overrides most local restrictions: cities must allow at least one ADU plus a junior ADU on nearly every single-family lot, cap review at 60 days, and can't require owner-occupancy on most new units.
BARC treats your ADU as the investment it is. Before we draw a single line, we run the numbers — buildable area, utility routing, construction cost, achievable rent, and the impact on your property value — so you green-light the project with a realistic pro forma, not a guess.
Why clients choose BARC
Feasibility Check First
We review your lot's setbacks, utilities, and zoning and give you a build-vs-don't-build answer with a realistic budget — before you commit to anything.
Pre-Approved & Custom Plans
Choose an agency pre-approved plan for faster permits or a custom design tailored to your lot and rental strategy.
Permits in 60 Days or Less
We package complete submittals that qualify for California's mandatory 60-day ADU review clock.
ADU Financing In-House
Renovation loans, HELOC alternatives, and construction financing arranged by our own loan team.
Fixed-Price Construction
A locked contract price with milestone payments — the way ADU construction should be bought.
Rental-Ready Handover
Separate address assignment, final inspections, and realtor guidance on pricing your new unit.
Explore this area
ADU Design & Build
Detached and attached new-construction ADUs.
Garage Conversions
The fastest, most affordable path to an ADU.
ADU Cost Guide
2026 California ADU cost breakdown.
ADU ROI Calculator
Estimate cost, rent, and payback for your lot.
How to Choose a Builder
What separates great ADU builders from the rest.
ADU Financing
Loan options that fund backyard homes.
Frequently Asked Questions
How much does an ADU cost in the Bay Area in 2026?+
Garage conversions typically run $125K–$220K. Detached new-construction ADUs run roughly $350–$550 per square foot all-in — about $250K–$400K for a 500–750 sq ft unit including design, permits, fees, and construction. Site conditions (slope, utility distance) move the number most.
How long does the whole ADU process take?+
Plan on 2–3 months for design and engineering, up to 60 days for city review (state-mandated cap), and 5–8 months of construction for a detached unit — roughly 9–14 months door to door. Garage conversions finish faster, often 6–9 months total.
Will an ADU raise my property taxes?+
Only on the value the ADU adds — your existing home is not reassessed. A $300K ADU adds roughly $3,300–$3,750/year in property tax, which typical Bay Area ADU rents cover in about one month.
Can I sell my ADU separately from my house?+
In most cases ADUs can't be sold separately (AB 1033 lets cities opt in to condo-style separate sales, and only a few have). The standard play is rental income plus resale value — both strong in Santa Clara County.
Do I need to live on the property to rent out my ADU?+
No. California suspended owner-occupancy requirements for ADUs permitted between 2020 and 2025, and most cities have made that permanent for standard ADUs. Junior ADUs (converted space inside the main home) still require owner-occupancy.
Related Services & Guides
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