ConstruBay

ADU Construction · Mill Valley, CA

ADU Builder —
Mill Valley, California

Fully Permitted Accessory Dwelling Units in Mill Valley

Mill Valley is one of the most desirable places to live in California — and an ADU on your property can generate $3,000–$5,000 per month in rental income while adding 15–20% to your property value. ConstruBay manages the entire Mill Valley ADU process from design through final permit sign-off. CSLB #1106798.

Start Your Mill Valley ADU

Options

01

Detached ADU

A separate structure on your property. Maximum privacy and rental value. Up to 1,200 sqft in most Mill Valley 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 in Mill Valley.

04

Junior ADU

Up to 500 sqft within your existing home footprint. Minimal permit requirements under California law.

Mill Valley ADU Facts

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Mill Valley permits ADUs up to 1,200 sqft detached

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Junior ADUs up to 500 sqft within existing footprint

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Average Mill Valley ADU rental: $3,500–$5,000/month

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ADU adds 15–20% to Mill Valley property value

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Permit process averages 4–6 months with ConstruBay

2026 Pricing

ScopeInvestment RangeTimeline
Standard ADU up to 800 sq ft$280,000 – $420,0004–6 months
Large ADU 800–1,200 sq ft$420,000 – $600,0006–8 months
Garage Conversion$150,000 – $280,0003–5 months
Junior ADU$80,000 – $150,0002–4 months

FAQ

How much does an ADU cost in Mill Valley?

ADUs in Mill Valley 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 Mill Valley?

Mill Valley ADU permits typically take 4–6 months. ConstruBay has established relationships with the Mill Valley building department that help keep applications moving.

What size ADU can I build in Mill Valley?

California law allows detached ADUs up to 1,200 sqft in most Mill Valley neighborhoods. Junior ADUs up to 500 sqft can be created within existing home footprints with streamlined permits.

Can I rent out my Mill Valley ADU?

Yes. Mill Valley allows ADU rentals. Average rental rates range from $3,000–$5,000 per month depending on size and location. An ADU typically increases property value by 15–20%.

Start Your Mill Valley ADU

We assess your property's ADU potential and provide a complete fixed-price proposal within 5 business days.

Start Your Mill Valley ADU
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