ADUs are the rare residential category that's grown faster than anyone in the industry expected. California issues over 25,000 ADU permits a year now. Los Angeles alone hit 10,000+. The boom is real — but if you're a contractor trying to win that work, "ADUs are booming" doesn't help you. What helps is knowing how to spot the early-stage filings, before the homeowner has locked in a builder.
Here's what the permit data actually shows you, and how to use it.
The two filings that matter most
ADU projects don't usually show up as a single permit. They show up as a sequence — and the first filing is where the opportunity is.
- Pre-application or zoning verification. Some cities expose this; some don't. If yours does, this is the earliest signal a homeowner is even thinking about an ADU.
- The ADU building permit. This is the moment most cities surface in their public data. The applicant is sometimes the homeowner directly, sometimes a designer, sometimes a contractor. If the contractor field is blank, no one's been hired yet.
That blank contractor field is the whole game. A homeowner who's filed permits but hasn't picked a builder is actively shopping. A homeowner whose permit lists "ABC Construction" already has an answer.
What ADU permits look like in practice
Most jurisdictions classify ADUs under one of these descriptions, depending on type:
- Detached new construction — standalone unit in the backyard. Usually 600-1,200 sq ft, $200K-$400K in major metros.
- Attached addition — bolted onto the main house. Cheaper to permit, harder to design well.
- Garage conversion — the most common type, and often the cheapest. Often $80K-$150K.
- Junior ADU (JADU) — interior conversion, shares utilities with main house. Usually under 500 sq ft.
If you're filtering permit data, search the permit description for ADU, accessory dwelling, secondary unit, or garage conversion. Don't rely on the permit type field alone — many cities still file ADUs under generic "residential addition" or "alteration" categories.
What to actually say when you reach out
The mistake most contractors make is leading with their pitch. The homeowner has been researching ADUs for months by the time they file a permit. They don't need to be sold on the concept — they need to be sold on you.
A working opening, after a fresh permit hits:
"Hi, I saw you pulled an ADU permit at [address]. I do a lot of ADU work in [neighborhood]. Quick question — have you locked in a contractor yet, or are you still gathering bids?"
If they've locked someone in, you thank them and move on. If they haven't, you're early enough to matter.
The cities to watch
ADU activity is heavily concentrated. As of the last full year of public data:
- Los Angeles — by far the highest volume; 10,000+ permits annually.
- San Diego — strong growth, especially detached ADUs.
- San Francisco — high-value market; fewer permits but bigger projects.
- Oakland, Berkeley, San Jose — Bay Area secondary markets where ADU rules just loosened.
- Seattle, Portland — solid pipeline; smaller average project size.
- Austin — growing fast since the 2023 zoning reform.
If you work outside California or the Pacific Northwest, ADU volume is lower — but the competition is also lower. Being the first contractor in your market to specialize in ADU construction can be a moat.
Where most contractors lose
Three avoidable mistakes:
- Treating ADUs like additions. Setbacks, height limits, parking exemptions, and utility connections all work differently. If you bid an ADU like a standard addition, you'll either lose money on the job or lose the bid by overpricing.
- Ignoring the design phase. Most ADUs are space-constrained. Homeowners care a lot about the layout. If you can offer design-build instead of "bring me your plans," you win bids your competitors can't.
- Waiting for the lead to come to you. ADUs are competitive in every active market. The contractors winning the work are the ones reaching out the day the permit is filed — not the week after.
Getting set up
If you want to track ADU permits across multiple cities without checking a dozen portals every morning, The Permit Sheet does exactly that. Start with a free alert — pick one city, filter for ADU keywords, and see what comes through your inbox for a week. If the volume's there, you'll know.