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Mill Valley, California: what can you build or do?

Plain-English answers to common homeowner questions, taken from Mill Valley's published ordinances, with every rule linked to the section it comes from.

Last reviewed 2026-10-14

• Accessory Dwelling Units (ADUs)
  Yes. Mill Valley allows ADUs on lots zoned for single-family or multifamily homes; on a single-family lot the city's handout allows up to one detached ADU, one conversion ADU and one junior ADU (JADU) inside the house. A detached ADU up to 800 sq ft, 16 feet tall and 4 feet from side and rear lines needs only a building permit; larger ADUs (up to 850 sq ft for a studio or one-bedroom, 1,000 sq ft for two or more bedrooms) need a ministerial ADU permit from the Planning Department first.Allowed with a permit
• Short-Term Rentals (Airbnb / VRBO)
  Yes. Mill Valley allows short-term rentals (under 30 consecutive days) in rooms, whole single-family homes and multifamily units, but not in deed-restricted ADUs or JADUs. Before your first guest you must register with the Planning Department ($181, renewed annually for $90), get a business license ($15 per unit + $4) and pay the city's transient occupancy tax monthly.Allowed with a permit
• Burn Permits & Backyard Fires
  Backyard brush or yard-waste burning isn't allowed in Mill Valley: the Bay Area Air District's Regulation 5, which covers Marin County, bans open burning except 17 listed fire types, mostly agricultural, training and fire-hazard burns that a public official must set or allow. Recreational fires using only clean dry wood, such as in a fire pit, and cooking fires are exempt, but recreational fires are banned during declared Mandatory Burn Ban (Spare the Air) periods. We didn't have Mill Valley's or Southern Marin Fire District's fire code, so local fire pit limits weren't reviewed.Restricted

We couldn't download Mill Valley's ordinance text for the other 7 topics yet, so we don't cover them rather than guess.