ADU Construction · Marin County
ADU Builder
Across Marin County
Fully Permitted Accessory Dwelling Units — Every Marin City
California's ADU laws have transformed what Marin County homeowners can build on their property. A well-designed ADU generates $3,000–$5,000 per month in rental income while adding 15–20% to your property value. ConstruBay manages the entire process — design, permits, construction — across every Marin County city and jurisdiction. CSLB #1106798.
Start Your Marin ADU ProjectOptions
01
Detached ADU
A separate structure on your property. Maximum privacy and rental value. Up to 1,200 sqft in most Marin County neighborhoods.
02
Attached ADU
An addition to your existing home. Cost-effective and ideal for multigenerational living.
03
Garage Conversion
Convert an existing garage into a fully permitted living space. Often the fastest permit path across Marin County.
04
Junior ADU
Up to 500 sqft within your existing home footprint. Minimal permit requirements under California law.
Cities Served
2026 Pricing
FAQ
How much does an ADU cost in Marin County?
ADUs in Marin County range from $80,000 for a Junior ADU to $600,000+ for a large detached unit. All ConstruBay ADU quotes include design, permits, construction and our 10-year warranty.
How long does ADU permitting take in Marin County?
ADU permits in Marin County average 4–6 months. ConstruBay has established relationships with all Marin County building departments that help keep applications moving.
What cities in Marin County does ConstruBay build ADUs?
We build ADUs throughout Marin County including Mill Valley, Tiburon, San Rafael, Sausalito, Ross, Belvedere, Kentfield, Larkspur, Corte Madera and Novato.
Can I rent out my Marin County ADU?
Yes. Most Marin County jurisdictions allow ADU rentals. Average rental rates range from $3,000–$5,000 per month. An ADU typically increases property value by 15–20%.
What size ADU can I build in Marin County?
California law allows detached ADUs up to 1,200 sqft in most Marin County neighborhoods. Junior ADUs up to 500 sqft can be created within existing home footprints.
Start Your Marin ADU Project
We assess your property's ADU potential and provide a complete fixed-price proposal within 5 business days.
Start Your Marin ADU Project