ADU Gallery & Costs
See our work and understand what it actually costs to build an ADU in Sonoma County.
Our ADU Projects
Built by hand. Designed to last.
Every ADU we build is a custom project — designed for the specific property, the homeowner's needs, and the local regulations. Here's a selection of our recent work. Click any photo to enlarge.
ADU Costs
How much does an ADU cost in Sonoma County?
The cost of building an ADU in Sonoma County depends on the size, complexity, site conditions, and the level of finishes you choose. Below are ballpark ranges based on our experience. These are all-in estimates that include design, permitting, construction, and standard finishes.
Every project is different, and we provide a detailed, transparent budget before any work begins. These ranges are meant to give you a starting point for planning — not a final quote.
300–500 sq ft
Studio ADU
$150,000 – $250,000
A compact, efficient space ideal for a rental unit, home office, or guest suite. Typically includes a kitchenette, bathroom, and open living/sleeping area. Studio ADUs are the most affordable to build and often the fastest to permit and construct.
Typically includes:
Foundation & framing
Full bathroom
Kitchenette or compact kitchen
HVAC system
Electrical & plumbing
Interior finishes
Permitting & plans
500–800 sq ft
1-Bedroom ADU
$250,000 – $400,000
The most popular ADU configuration. A separate bedroom provides privacy and makes the unit more attractive to long-term renters and family members. This size allows for a full kitchen, a comfortable living area, and a proper bedroom with closet space.
Typically includes:
Foundation & framing
Full bathroom
Full kitchen
Separate bedroom
Living area
HVAC system
Washer/dryer hookups
Permitting & plans
800–1,200 sq ft
2-Bedroom ADU
$400,000 – $600,000+
A full-sized dwelling that can comfortably house a small family or serve as a premium rental. At this size, an ADU feels like a complete home — with a full kitchen, living room, two bedrooms, and often two bathrooms. These units command the highest rental rates and add the most value to your property.
Typically includes:
Foundation & framing
Two full bathrooms
Full kitchen
Two bedrooms
Living & dining areas
HVAC system
Washer/dryer hookups
Exterior finishes
Landscaping allowance
Permitting & plans
Cost Factors
What affects the cost of your ADU?
Site conditions. Sloped lots, difficult access, poor soil, or the need for retaining walls can add to the cost. A flat, easily accessible lot with good soil is the most straightforward (and affordable) scenario.
Utility connections. If your ADU requires new sewer, water, or electrical connections — rather than tapping into existing lines — that adds cost. The distance from existing utilities to the ADU site is a key factor.
Finishes and fixtures. The range between standard and high-end finishes can be significant. Custom cabinetry, premium countertops, designer fixtures, and hardwood flooring will push costs toward the higher end of the range. We help you make smart choices that balance quality and budget.
Design complexity. A simple rectangular footprint is more affordable to build than a complex shape with multiple rooflines, large windows, or custom architectural details. That said, a well-designed ADU doesn't have to be expensive — good design is about smart decisions, not just spending more.
Permitting and fees. Impact fees are waived for ADUs under 750 sq ft in Sonoma County. For larger units, fees can range from a few thousand to $15,000+, depending on the jurisdiction. We factor these into our budgets from the start.
Want a cost estimate for your property?
Every property is different. We'll visit your site, discuss your goals, and provide a detailed estimate — no obligation, no pressure.