Yes, in most cases. On a single-family lot in Novato or Petaluma you can build one accessory dwelling unit, plus one junior ADU carved out of your main home, and rent the unit out long term without living on the property yourself. California law has made this one of the most straightforward ways to add living space and income to an existing house, and both towns have adjusted their own rules to match. Here is what actually applies in Novato and Petaluma in 2026, so you can find out what your lot allows without wading through a zoning code.
What state law allows on your lot
Statewide rules govern most ADUs. A detached unit can be up to 1,200 square feet, and cities may not set a lower maximum; an attached unit is capped at 1,000 square feet; a junior ADU inside the main house is capped at 500 square feet. Detached ADUs generally cap at 16 feet tall, or 18 feet within half a mile of a major transit stop, while attached units can reach 25 feet or the zone's height limit, whichever is lower. Cities cannot impose a front-yard setback or a minimum lot size, and side and rear setbacks cannot exceed 4 feet.
You get one ADU plus one JADU on a single-family lot. Since January 2020, no city can require you to live on the property, and long-term rentals are allowed; short-term rentals, like Airbnb, are subject to each city's local rules.
Novato: one permit, not two
Novato made this simpler in January 2025, when it eliminated the separate planning permit for ADUs. Today, most projects need only a building permit. ADUs are allowed on any lot with an existing or proposed single-family or multifamily home, and JADUs get relaxed requirements including no added parking and no fire-sprinkler requirement.
Petaluma: no new parking required
Petaluma allows ADUs in residential and mixed-use zones with ministerial approval, which means no public hearing or discretionary review. A detached unit in the streamlined tier can be up to 800 square feet of interior living space, and a standard ADU can go to 1,200 square feet depending on your zone. Petaluma also does not require additional parking for an ADU.
What it costs, and how people pay for it
A Bay Area ADU typically lands in the $150,000 to $400,000-plus range depending on size, type, and site work. Financing is available beyond a cash build: home equity lines, ADU-specific loan programs, and some grants can spread the cost, and the rental income is what makes the monthly payment workable for many owners. I have spent my career around construction, mechanical systems, and income property, so I can help you get a realistic read on costs before you commit.
An ADU also changes the math of a sale. For a buyer, a rented unit offsets a mortgage payment and can make a purchase affordable that otherwise would not be. For a seller, an income-producing unit broadens the pool of interested buyers. And for investors, it is one more unit of rent on a property you already own.
Helpful next steps
“An ADU is one of the few home improvements that pays you back every month. Done right, it is income, flexibility, and value in one building.”
Peter Schardt
Written by
Peter Schardt
21 years in real estate, 100+ homes sold, and a lifetime in the North Bay. Sales Associate · 01702383 · California.
