How many ADUs should a builder have completed before I hire them?

There's no official minimum, but look for a builder who can point to several completed, permitted ADUs in your specific city or county, not just general construction experience. A contractor with two or three verifiable, finaled ADU permits nearby is a safer bet than one with decades of remodeling experience but no local ADU track record.

Is it okay to hire a handyman or unlicensed contractor for an ADU to save money?

No. ADUs generally require a licensed general contractor because the scope involves structural work, utilities, and code compliance that falls outside what an unlicensed handyman is legally permitted to perform in most states. Unpermitted or improperly licensed work can jeopardize your insurance and your ability to legally occupy or rent the unit.

How do I check if an ADU builder's license is actually valid?

Use your state's official contractor licensing board lookup tool rather than trusting a license number a builder gives you verbally. Most state boards, like California's CSLB, offer an online search at no cost that shows license status, classification, bonding, and insurance in real time.

How many bids should I get before choosing an ADU builder?

Most homeowners get at least three comparable bids. That's enough to see a realistic price range for your project and spot a bid that's an outlier — either unrealistically low or padded above what the market supports — without dragging the process out for months.

What's the biggest mistake homeowners make when choosing an ADU builder?

Picking based on price alone without checking permit history or calling references from older projects. A low bid from a builder with a spotty permit record often ends up costing more once change orders, delays, or unfinished inspections enter the picture.

How Do I Choose an ADU Builder? A Practical Vetting Checklist

Building an accessory dwelling unit is one of the more complex projects a homeowner takes on, and the builder you pick matters more than almost any other decision in the process. A general remodeler who's never pulled an ADU permit can stumble on things a specialist handles routinely — separate utility connections, setback rules, second-unit fire and egress requirements. Here's what actually separates a builder worth hiring from one to avoid.

Do They Have Real ADU Experience, Not Just General Remodeling Experience?

An ADU isn't a kitchen remodel or a room addition. It involves its own permitting path, often its own utility connections, and rules that vary by jurisdiction — setbacks, height limits, parking, sometimes owner-occupancy requirements depending on your city and state. A contractor who's built additions and kitchens for 20 years but has done one or two ADUs is still learning the process on your project.

Ask directly: "How many ADUs have you built in this city or county in the last two years?" A builder who specializes in ADUs should be able to name the jurisdiction's plan check department by name and tell you roughly how long permitting typically takes there. If they can't, that's a sign they're generalizing from experience elsewhere, which doesn't always transfer — permitting requirements, fee structures, and inspector expectations differ from one city to the next.

Is Their License Active, and Does It Cover This Kind of Work?

Every state licenses contractors differently, but the step is the same everywhere: look up the license yourself rather than taking the contractor's word for it. Most states run an online license lookup at no cost through their contractor licensing board. In California, that's the Contractors State License Board's Check a License tool. If you're not sure which agency covers your state, the National Association of State Contractors Licensing Agencies keeps a directory of all of them.

When you look the license up, check three things: that it's active (not expired, suspended, or revoked), that the classification covers the scope of an ADU build (in states with classification systems, a general building license is usually required — a narrow specialty license, like electrical-only, isn't enough to act as your general contractor), and that bonding and insurance are current. A lapsed bond or missing workers' comp coverage means you could be on the hook if something goes wrong on your property.

What Does Their Permit Track Record Actually Look Like?

Anyone can say they're experienced. A permit history is harder to fake. Ask the builder for two or three recent ADU addresses (or permit numbers) in your jurisdiction, then check the local building department's public permit portal, if one exists, to see whether those permits were pulled, inspected, and closed out — not left open or abandoned partway through. A pattern of permits that stall out or never get finaled is one of the clearer warning signs available to a homeowner before signing anything.

This matters because an ADU with unpermitted or unfinaled work can complicate your insurance, your resale, and your ability to legally rent the unit. For more on what permitting actually requires, see Do I Need a Permit for an ADU? What the Law Actually Requires.

Who Should You Call as a Reference, and What Should You Ask?

A reference list a contractor hands you is pre-filtered — of course those homeowners are happy. Ask for at least one reference from a project completed 12 or more months ago, not just recent jobs where memories (and any punch-list frustrations) are still fresh. A project a year or two out tells you whether things held up: whether the roof still doesn't leak, whether the builder came back for warranty issues without a fight.

When you call, ask specific questions rather than "were you happy": Did the project finish close to the original timeline? Did the final cost match the bid, or were there large unexplained change orders? Would they hire this builder again for a second project? The Federal Trade Commission's guidance on hiring a contractor recommends checking with your local home builders association and consumer protection office for complaints, in addition to calling references directly.

How Do You Compare Bids That Don't Look Alike?

ADU bids often look wildly different not because one builder is ripping you off, but because they're pricing different scopes — one may include landscaping restoration and a fence, another may not. Before comparing dollar totals, line up what's actually included: permits and fees, utility hookups, site prep, finishes, appliances, and warranty terms. Our guide on what should be in an ADU builder's bid walks through the line items a complete bid should cover.

This is also where getting multiple quotes pays off in a way a single bid never can. One number in isolation tells you almost nothing — you have no way to know if it's fair. Two or three comparable bids from vetted builders let you see the going rate for your specific project and catch outliers, whether that's a bid that's suspiciously low or one padded well above the rest.

What Red Flags Should Stop You From Signing?

A few signs are worth treating as dealbreakers rather than minor concerns: a demand for a large upfront deposit before any work starts, pressure to sign the same day you meet, no written contract or estimate, and a request that you pull the permits yourself so the work stays off the builder's record. The FTC flags all of these as common tactics tied to unlicensed or unreliable contractors, and they hold up as a useful checklist regardless of which state you're in.

A realistic build also takes time. If a builder promises a turnaround dramatically faster than what a realistic ADU timeline looks like in your area, treat that as optimism to verify, not a guarantee to bank on.

What to Do About It

Start by pulling the contractor's license yourself through your state's official lookup tool — don't rely on a screenshot or a card they hand you. Then ask for ADU-specific permit addresses you can verify locally, and call at least one reference whose project is over a year old. Line up bids side by side on scope, not just price, before you decide. And if you're still early in the process, getting a few comparable, no-cost quotes from vetted local builders is the fastest way to find out what a fair price and a realistic timeline actually look like for your project — instead of hoping the first number you hear is a good one.