Hiring a contractor

How to get ADU contractor bids

This site does not recommend or screen contractors. The homepage can show nearby license records copied from the Contractors State License Board (CSLB). That list is not a recommendation. You can check a license yourself on the CSLB website, ask several licensed contractors for written bids on the same scope, and read the contract before work starts. The rules below are for a homeowner adding an ADU. CSLB's April 2026 newsletter applies the home improvement payment limits to constructing an ADU. Each section links to the statute or CSLB page it comes from. Accessed October 20, 2026.

Last reviewed October 20, 2026

1 · Start here

Short answer

Check the license on CSLB's website before you hire. Read the status, the classification, the bond, and the workers' compensation line. Call CSLB at 800-321-CSLB (2752) if you cannot use the website.
Get at least three written bids, on the same plans and the same scope. CSLB says not to take the lowest bid just because it is the lowest.
For a home improvement contract over $500, the contract has to be in writing and signed before that work starts. It has to name the contractor, the license number, the price, the work, and the schedule.
The down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less. Later payments may not get ahead of work already done or materials already delivered. A narrow bond exception is described below.
You may have three business days to cancel, five if you are 65 or older, or seven for some disaster-repair contracts. The right does not attach to every contract. See the cancellation section.
Unpaid contractors, subcontractors, and suppliers can record a mechanics lien. Ask for lien releases as you pay.
If a contractor is doing the job, CSLB says that contractor should pull the building permits. Signing the permit yourself as an owner-builder puts the owner's responsibilities on you.

Sources: CSLB, Check a License · CSLB, How do I find the right licensed contractor? · CSLB, What You Should Know Before Hiring a Contractor (May 2025, PDF) · Cal. Bus. & Prof. Code §7159 (home improvement contract) · Cal. Bus. & Prof. Code §7159.5 (down payment and progress payments) · CSLB, California Licensed Contractor newsletter (April 2026, PDF)

2 · The license

Check the license, classification, bond, and workers' comp

Use CSLB's Check a License page. You can search by license number, business name, or a person's name. CSLB says the license number has to appear on advertisements, business cards, bids, and the contract. A number on a card is not enough by itself. Open the license record and read it.

Status

Read whether the license is current and active. CSLB says work done while a license is suspended is treated as unlicensed. Contracting without a required license is a misdemeanor under Bus. & Prof. Code §7028. A license is required if the work needs a building permit, if the person uses employees, or if the combined price of labor, materials, and other items is $1,000 or more. The under-$1,000 exemption also does not apply when a building permit is required, so it does not cover an ADU that needs a permit.

Classification

The license record lists classification codes. A B – General Building contractor is defined in Bus. & Prof. Code §7057. In short, a B contractor's contracting business is structures, and a prime contract that goes beyond framing or carpentry has to involve at least two unrelated building trades other than framing or carpentry, unless that contractor holds the specialty classification or subcontracts that part to someone who does. Framing or carpentry does not count as one of those two trades. Read the codes on the license and ask which classification covers the ADU, including foundation, electrical, and plumbing. This page does not name one classification for every prefab ADU. Ask which license covers the site work, and check that license too.

Bond

An active license has to have a contractor bond of $25,000 on file with CSLB (Bus. & Prof. Code §7071.6). The license record shows the surety, the bond amount, and the effective date. CSLB's bond guide says the bond is there so a person who is harmed by a license-law violation, property damage, or unpaid wages may make a claim. CSLB also says the bond often is not large enough for a big job or for more than one claim, and that a bond does not assure the contractor's skill or honesty. This page does not restate the split of bond money among different kinds of claimants in §7071.6(b). Read that section if you are thinking about a claim.

Workers' compensation and liability insurance

If the contractor has employees, California requires workers' compensation insurance. The license record shows the insurer and the policy dates, or an exemption the contractor filed saying they have no employees. CSLB says these classifications must carry workers' compensation, or a Certification of Self-Insurance, even when they have no employees: C-8 Concrete, C-20 Warm-Air Heating, Ventilating and Air-Conditioning, C-22 Asbestos Abatement, C-39 Roofing, and C-61/D-49 Tree Service. CSLB warns that if a worker is hurt on your property and the contractor has no coverage, you could be asked to pay. Commercial general liability insurance is not required. It can cover damage to your property. The written contract has to say whether the contractor carries general liability insurance and whether they carry workers' compensation or are exempt.

CSLB's license check says public complaint information is limited by Bus. & Prof. Code §7124.6. A record that lists no complaint is not a finding that nobody has complained, and it is not a reason by itself to hire the contractor. When the person visits, CSLB says to ask for the pocket license and a photo ID, and to make sure the person matches the license. A salesperson who solicits the contract has to be registered with CSLB as a Home Improvement Salesperson. Ask for that registration card too.

Sources: CSLB, Check a License · CSLB, How do I find the right licensed contractor? · CSLB, What You Should Know Before Hiring a Contractor (May 2025, PDF) · CSLB, Fast Facts: A Guide to Contractor License Bonds (2025, PDF) · CSLB, Workers' Compensation Requirements · CSLB, guide for city and county building departments · CSLB, Industry Bulletin 24-07: minor-work exemption rises to $1,000 (PDF) · Cal. Bus. & Prof. Code §7028 (contracting without a license) · Cal. Bus. & Prof. Code §7048 (minor-work exemption) · Cal. Bus. & Prof. Code §7057 (B – General Building classification) · Cal. Bus. & Prof. Code §7071.6 (contractor license bond) · Cal. Bus. & Prof. Code §7124.6 (limits on public complaint disclosure) · Cal. Bus. & Prof. Code §7125 (workers' compensation) · Cal. Bus. & Prof. Code §7159 (home improvement contract)

3 · Bids

Get several written bids on the same scope

CSLB tells homeowners to get at least three written bids and to compare them on the same plans, specifications, and scope of work. Give every bidder the same description of the ADU: size, type (detached, attached, conversion, or junior), whether it is site-built or prefab, what is included (foundation, utilities, permits, plans, cleanup), and what is not. CSLB says not to accept the lowest bid automatically, and to be wary of a bid that is far below the others. A very low bid can mean something was left out.

State law does not set a required number of bids for a private homeowner. The "at least three" figure is CSLB's advice, not a statute. There is also no statewide rule that forces bidders to use one form. What the law does require, once you hire someone for a home improvement over $500, is a written contract with the items in the next section. Ask each bidder to put the price, the scope, and the exclusions in writing so you can compare them before you pick one.

Sources: CSLB, How do I find the right licensed contractor? · CSLB, Construction Project Checklist (2025, PDF) · CSLB, What You Should Know Before Hiring a Contractor (May 2025, PDF) · Cal. Bus. & Prof. Code §7159 (home improvement contract)

4 · The contract

What a home improvement contract has to include

Bus. & Prof. Code §7151 defines home improvement to include repairing, remodeling, altering, converting, modernizing, or adding to residential property, and improvements on land next to a dwelling. CSLB's April 2026 newsletter says the down-payment and progress-payment limits apply to constructing an ADU. A home improvement contract, for §7159, is an agreement for that work when the total price for labor, services, and materials is more than $500. It can be one document or several. It has to be in writing, legible, and signed by the parties before the work it covers starts. Before work starts, the contractor has to give you a copy signed and dated by both of you.

The contract, or a required attachment, has to include these items. This is a plain-language list of §7159, not every formatting rule:

The contractor's name, business address, and license number, and, if a salesperson negotiated it, that person's name and registration number.
A "Home Improvement" heading, the date you signed, and where to send a notice of cancellation, including an email address and a phone number.
The contract price in dollars and cents. Any finance charge is listed separately, under its own heading, and is not folded into the contract amount.
A description of the project and of the significant materials and equipment. CSLB says the description should be specific: what will be done, who does it, and the materials.
The down payment, if any, and the statement that it may not exceed $1,000 or 10 percent of the contract price, whichever is less.
A schedule of progress payments, if you will pay before the job is finished. Each payment has to name the work, services, materials, or equipment it covers.
What counts as substantial commencement of the work, an approximate start date, and an approximate completion date.
A note that extra work and change orders become part of the contract only when they are written and signed before that extra work starts, and that they have to state the scope, the price change, and the effect on the schedule.
Whether subcontractors will be used. If yes, the contractor has to give you, on request, each subcontractor's name, contact information, license number, and classification.
A statement that, once you have paid for a portion of the work, the contractor has to give you a full unconditional release from mechanics liens for that portion before you pay more.
Notices about commercial general liability insurance, workers' compensation, a mechanics lien warning, CSLB's contact information, and the cancellation notice that applies to your contract.
Near the signatures, a notice that you have the right to require the contractor to have a performance and payment bond. That bond is separate from the $25,000 license bond.

Changes have to be written change orders signed before the extra work begins. CSLB's checklist also says to keep a paper copy and to read it before you sign. The contract has to be in the same language that was mainly used in any spoken sales presentation.

Sources: Cal. Bus. & Prof. Code §7151 (home improvement) · Cal. Bus. & Prof. Code §7159 (home improvement contract) · Cal. Bus. & Prof. Code §7159.5 (down payment and progress payments) · CSLB, What is a home improvement contract? · CSLB, California Licensed Contractor newsletter (April 2026, PDF) · CSLB, Construction Project Checklist (2025, PDF)

5 · The down payment

The down payment limit: $1,000 or 10 percent, whichever is less

For a home improvement contract, if there is a down payment, it shall not exceed $1,000 or 10 percent of the contract amount, whichever is less (Bus. & Prof. Code §7159.5(a)(3)). The contract has to show the down payment and, in at least 12-point bold type, the sentence that the down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less. The contract amount includes profit, labor, and materials, and excludes finance charges. CSLB says there is no exception for special-order materials.

Examples, using that rule: on a $40,000 contract, 10 percent is $4,000, so the cap is $1,000. On a $6,000 contract, 10 percent is $600, so the cap is $600. CSLB's April 2026 newsletter applies this cap to constructing an ADU, and also to rebuilding a home in a declared disaster area.

There is a narrow exception in §7159.5(a)(8). A contractor who furnishes a performance and payment bond, a lien and completion bond, or a bond equivalent or joint control covering full performance and payment, on file with CSLB, does not have to follow the down-payment cap or the progress-payment limits. CSLB says this blanket performance and payment bond is uncommon, on the order of two dozen licensees, and that those contractors can ask for the full price up front. If someone tells you they are in that group, look at the license record and ask CSLB before you pay more than the cap. The contractor also may not have a financial interest in a joint control they arrange.

Sources: Cal. Bus. & Prof. Code §7159 (home improvement contract) · Cal. Bus. & Prof. Code §7159.5 (down payment and progress payments) · CSLB, What is a home improvement contract? · CSLB, How do I find the right licensed contractor? · CSLB, California Licensed Contractor newsletter (April 2026, PDF) · CSLB, Industry Bulletin: progress payment restrictions (2022, PDF)

6 · Progress payments

Payments should not get ahead of the work

Except for the down payment, the contractor shall neither request nor accept payment that exceeds the value of the work performed or material delivered (§7159.5(a)(5)). That limit also covers money paid up front by a lender or a financing company for the home improvement. If the contract lets you pay in stages before the end, it needs a schedule of progress payments. Each amount has to be in dollars and cents and has to name the work, services, materials, or equipment for that payment. The schedule has to include a statement, in at least 12-point bold type, that it is against the law for a contractor to collect payment for work not yet completed, or for materials not yet delivered, and that a contractor may require a down payment.

A practical way to read a schedule: the payment for a phase should match that phase, not the whole job. A large payment due before the foundation, framing, or delivery it is supposed to cover is the pattern §7159.5 prohibits, unless the bond exception above applies. CSLB's checklist says not to let payments get ahead of the work.

Sources: Cal. Bus. & Prof. Code §7159 (home improvement contract) · Cal. Bus. & Prof. Code §7159.5 (down payment and progress payments) · CSLB, Industry Bulletin: progress payment restrictions (2022, PDF) · CSLB, Construction Project Checklist (2025, PDF) · CSLB, California Licensed Contractor newsletter (April 2026, PDF)

7 · Canceling

The right to cancel, and when it applies

You do not get the same cancellation window on every contract. Read the notice in your contract. These are the rules in Bus. & Prof. Code §7159 and Civil Code §§1689.5–1689.14.

Three business days. For a home improvement contract that was not negotiated at the contractor's place of business, the contract has to include a Three-Day Right to Cancel notice. You may cancel by email, mail, fax, or delivery of a written notice, by midnight of the third business day after you received a signed and dated copy of the contract.
Five business days if you are a senior citizen. The same notice uses five business days instead of three. Civil Code §1689.5 defines senior citizen, for these cancellation rules, as a person who is 65 or older. The five-day right applies to contracts entered into on or after January 1, 2021.
Not this notice, if you negotiated at the contractor's place of business. Section 7159 says the three-day and five-day notices are not the ones provided when the contract is negotiated at the contractor's place of business (unless the seven-day disaster notice applies instead). "Place of business" lines up with Civil Code §1689.5, which talks about the premises where the seller normally carries on the business.
Seven business days for certain disaster repairs. A contract written to repair or restore a home damaged by a sudden or catastrophic event, after a federal, state, or local emergency declaration, has to include a Seven-Day Right to Cancel notice. Cancel by midnight of the seventh business day after you received the signed and dated copy.
Some disaster contracts are void. Under Civil Code §1689.14, a home solicitation contract to repair or restore a damaged home, signed on or after the date of the disaster and through midnight of the seventh business day after that date, is void unless you (or your agent or insurer) solicited it at the contractor's place of business. A call you make to that place of business counts as your solicitation.
Emergency repairs you asked for can waive the right. Civil Code §1689.13 can set the cancellation rules aside when you started the contact, the work is immediately necessary to protect people or property, and you sign a separate dated statement that describes the emergency and waives the three-day, five-day, or seven-day right. An ADU project is not that kind of emergency repair.

A business day, for these rules, is any calendar day except Sunday and a listed set of holidays: New Year's Day, Washington's Birthday, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day, and Christmas Day (Civil Code §1689.5). Saturday counts. If you mail the notice, cancellation is effective when you deposit it, properly addressed, with postage paid. The notice does not have to be on the form they gave you, as long as it says you do not want to be bound. If you cancel, the contractor has to return anything you paid within 10 days after receiving your notice. You have to make goods they delivered available to them, with the details printed in the notice.

Your copy of the signed, dated contract is what starts the cancellation time under §7159. If the cancellation notice that belongs in the contract is missing, you can complain to CSLB.

Sources: Cal. Bus. & Prof. Code §7159 (home improvement contract) · Cal. Civ. Code §1689.5 (home solicitation and senior citizen) · Cal. Civ. Code §1689.6 (right to cancel) · Cal. Civ. Code §1689.13 (emergency-repair waiver) · Cal. Civ. Code §1689.14 (disaster contracts that are void) · CSLB, Construction Project Checklist (2025, PDF) · CSLB, Fast Facts: Rebuilding After a Disaster (PDF)

8 · Liens

Mechanics liens and lien releases

A mechanics lien is a claim recorded against your property by someone who improved it and was not paid. The warning that §7159 requires in the contract says that even if you pay your contractor in full, an unpaid subcontractor, supplier, or laborer may record a lien and sue to foreclose it. A court that finds the lien valid can order you to pay, including paying twice, or can order a sale of the home. The warning also says a lien can affect your credit.

Subcontractors and material suppliers generally have to give you a preliminary notice to preserve a lien. The statutory warning says that notice can arrive up to 20 days after the subcontractor starts or the supplier delivers materials, and that you will not get one from your prime contractor or from laborers. CSLB and the statute both suggest getting a list of subcontractors and suppliers, noticing when they start, and watching the mail for 20 days before you pay that portion.

Deadlines to record a claim of lien, from the Civil Code: a direct contractor (the one in contract with you) has to record after finishing their contract and before the earlier of 90 days after completion of the work of improvement, or 60 days after you record a notice of completion or cessation (§8412). Other claimants have to record before the earlier of 90 days after completion, or 30 days after that notice (§8414). "Completion" has its own definition in the lien statutes. This page does not restate every way a job can count as complete. If a lien is recorded, read CSLB's page on what to do next and talk with a lawyer. Waiting can cost you the chance to contest it.

Lien releases. On any payment, and before the next one, the contractor has to, if you ask, give you a full unconditional release from lien claims for the part you have paid. You may withhold further payments until you get those releases (§7159.5(a)(6)). The contract itself has to say this. California uses statutory waiver forms. A release that does not substantially follow the form is not effective (Civil Code §8122 and §§8132–8138):

Conditional waiver and release on a progress payment (§8132). It takes effect when the claimant actually receives the payment. The form itself says not to rely on it unless you are satisfied the claimant has been paid.
Unconditional waiver and release on a progress payment (§8134). The claimant states they have been paid. Do not treat an unconditional release as done until the money has cleared.
Conditional waiver and release on final payment (§8136), and unconditional waiver and release on final payment (§8138). Same idea, at the end of the job.

The statutory warning also describes paying with a joint check, payable to the contractor and the subcontractor or supplier who sent a preliminary notice. That is one way to see that the person who could lien you is named on the check.

Sources: Cal. Bus. & Prof. Code §7159 (home improvement contract) · Cal. Bus. & Prof. Code §7159.5 (down payment and progress payments) · Cal. Civ. Code §8122 (lien waivers) · Cal. Civ. Code §8132 (conditional waiver on a progress payment) · Cal. Civ. Code §8134 (unconditional waiver on a progress payment) · Cal. Civ. Code §8136 (conditional waiver on final payment) · Cal. Civ. Code §8138 (unconditional waiver on final payment) · Cal. Civ. Code §8412 (direct contractor lien deadline) · Cal. Civ. Code §8414 (subcontractor and supplier lien deadline) · CSLB, Understanding Mechanics Liens · CSLB, What if a mechanics lien is filed on your property?

9 · Permits

Permits, and the risks of being an owner-builder

A city or county that requires a building permit also has to require a signed statement from the applicant. A licensed contractor states the license number and that the license is in full force and effect. Someone who claims to be exempt states the basis for the exemption (Bus. & Prof. Code §7031.5). CSLB's checklist says to ask who will obtain the permits and schedule the inspections, and that the contractor should pull the permits. CSLB's disaster guide says to check with the building department even if a contractor tells you no permit is needed.

An owner-builder is an owner who takes on the job instead of hiring a licensed general contractor to run it. Signing the permit application as an owner-builder is the usual way that happens. CSLB says you then assume responsibility for the project. That can include scheduling the work, getting permits, calling inspections, fixing work that fails inspection, and paying workers and suppliers. If you hire unlicensed people, CSLB says you may be treated as their employer, which can mean payroll taxes and workers' compensation. Unpaid subcontractors and suppliers can still record mechanics liens. CSLB also warns about unlicensed people who offer, for a fee, to walk you through the owner-builder process. CSLB says that is against the law.

The license exemption for owners is limited. Bus. & Prof. Code §7044 is the statute. CSLB's overview restates three situations in which a license is not required: you do the work yourself or through your own employees paid wages, and the structure is not intended for sale; you contract directly with licensed subcontractors for the trades, with a limit of four single-family structures intended for sale in a calendar year unless you hire a general contractor; or you are improving your principal residence, the work is done before sale, you have lived there for the 12 months before completion, and you have not used this residence exemption on more than two structures in any three-year period. The statute's sentence on that two-structure limit is awkward ("on more than two structures more than once during any three-year period"). Read §7044 itself before you rely on a count. A sale or offer to sell within one year after completion is, under §7044(b), evidence that the work was undertaken for sale.

Hiring a licensed contractor to pull the permit does not remove your job of reading the contract and checking the license. It does keep you from signing on as the person who is running the construction.

Sources: Cal. Bus. & Prof. Code §7031.5 (license statement on a building permit) · Cal. Bus. & Prof. Code §7044 (owner-builder exemption) · CSLB, Construction Project Checklist (2025, PDF) · CSLB, Fast Facts: Rebuilding After a Disaster (PDF) · CSLB, Owner-Builder Risks · CSLB, Owner-Builder Overview · CSLB, guide for city and county building departments

10 · Red flags

Red flags

These are patterns CSLB tells consumers to treat as warning signs. None of them, by itself, decides a legal dispute. They are reasons to stop and check before you pay or sign.

No license, a license that is not current and active, or a person at your door who will not show a pocket license and a photo ID that match. Unlicensed advertising has to say the person is not licensed.
A down payment over $1,000 or over 10 percent of the price, whichever is less, or a demand to be paid for work that is not done or materials that have not arrived.
Cash only, or a request to cash your check on the spot. CSLB says to avoid cash and not to pay cash, and to keep copies of checks.
Door-to-door offers, especially high pressure, "leftover materials," a price that will not be put in writing, or a push to start today. CSLB's traveler-scam sheet describes these tactics. After a disaster, a contract to repair the home that a solicitor brings to you in the first seven business days can be void. See the cancellation section.
A bid far below the others, or a refusal to describe what is included.
No written contract before work starts, or a change in the work with no written change order.
"You don't need a permit." Check with the city or county building department.
After a declared emergency, a price for repair or reconstruction more than 10 percent above what that contractor charged just before the emergency. Penal Code §396 makes that unlawful for 180 days after the declaration, unless the contractor can show the increase comes from added supplier, labor, or material costs and still stays within the markup the statute allows. Building materials and some other goods have a 30-day version of the rule, with its own cost exception. Report price gouging to the local district attorney or to CSLB. CSLB's disaster sheet says the same thing in shorter form.

Sources: CSLB, What You Should Know Before Hiring a Contractor (May 2025, PDF) · CSLB, Guard Against Traveling Contractor Scams (PDF) · CSLB, Fast Facts: Rebuilding After a Disaster (PDF) · CSLB, How do I find the right licensed contractor? · CSLB, Construction Project Checklist (2025, PDF) · Cal. Bus. & Prof. Code §7159.5 (down payment and progress payments) · Cal. Civ. Code §1689.14 (disaster contracts that are void) · Cal. Penal Code §396 (price increases during an emergency) · Cal. Bus. & Prof. Code §7048 (minor-work exemption)

11 · Questions

Questions to ask each bidder

CSLB's checklist and hiring pages are the source of most of these questions. The ADU-specific ones (prefab or site-built, and who draws the plans) are practical questions so the bids match. They are not extra legal requirements.

What is your CSLB license number and classification? Then check it on CSLB's website, including the bond and workers' compensation lines.
Can I see your pocket license and a photo ID? If a salesperson is here, can I see their Home Improvement Salesperson registration?
How many ADUs like this one have you built, and can I speak with those clients? CSLB says to ask about experience with this type of project and to check referrals.
Will this ADU be site-built or prefab? What does the bid include, and what does it leave out: plans, permits, foundation, utilities, delivery and setting the unit, and cleanup?
Who prepares the plans, and who submits them and the permit to the building department? Who schedules inspections?
What is the approximate start date, what counts as substantial commencement, and what is the approximate completion date?
Who is on the job each day? Will you use subcontractors? Please list their names, license numbers, and classifications.
Do you have employees? Show me the workers' compensation information. Do you carry commercial general liability insurance?
How is each payment tied to a phase of work? What is the down payment?
If the scope changes, will you write a change order and sign it with me before that work starts?

Sources: CSLB, Construction Project Checklist (2025, PDF) · CSLB, How do I find the right licensed contractor? · CSLB, What You Should Know Before Hiring a Contractor (May 2025, PDF) · Cal. Bus. & Prof. Code §7159 (home improvement contract)

Before you sign

A short order of work, drawn from the CSLB pages and statutes linked above.

Write down the same scope for every bidder: ADU type, size, site-built or prefab, and what is included.
Check each license on CSLB's website. Read status, classification, bond, and workers' compensation.
Compare at least three written bids on that same scope. Set aside a bid that is far below the others until you know what it leaves out.
Read the contract. Confirm the price, the down payment, the progress-payment schedule, the dates, the permit line, and the cancellation notice.
Pay no more than $1,000 or 10 percent up front, whichever is less, unless you have confirmed the narrow bond exception with CSLB.
Ask who pulls the permit. If you are asked to sign as an owner-builder, read CSLB's owner-builder pages first.
As you pay, ask for lien releases for the work covered by that payment.
For the state ADU size, setback, and fee rules on your lot, use the free research summary on this site. It is not a permit and it is not a contractor referral.

Sources: CSLB, How do I find the right licensed contractor? · CSLB, Construction Project Checklist (2025, PDF) · CSLB, Owner-Builder Risks · Cal. Bus. & Prof. Code §7159 (home improvement contract) · Cal. Bus. & Prof. Code §7159.5 (down payment and progress payments)

Quick answers

How do I check a California contractor license?

Use CSLB's Check a License page, or call 800-321-CSLB (2752). Read whether the license is current and active, the classification, the $25,000 contractor bond, and the workers' compensation line or exemption. A license number on a business card is not a substitute for that check.

How many ADU bids should I get?

CSLB says at least three written bids, compared on the same plans and scope. That number is CSLB's advice to consumers. It is not a statute that requires three bids.

What is the most I can pay a contractor up front in California?

On a home improvement contract, the down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less (Bus. & Prof. Code §7159.5). CSLB applies that limit to ADU construction. A contractor with a blanket performance and payment bond on file with CSLB is the uncommon exception.

Can the contractor bill me for the next phase before it is done?

No, aside from the down payment and the bond exception. The contractor may not request or accept payment that exceeds the value of work performed or material delivered.

How long do I have to cancel a home improvement contract?

Often three business days after you receive the signed, dated contract, or five business days if you are 65 or older. Some disaster-repair contracts have seven business days. The three-day and five-day notices are not the ones §7159 requires when the contract was negotiated at the contractor's place of business. Read the notice in your contract.

What is a mechanics lien?

A recorded claim against your property by someone who helped improve it and was not paid. Paying your contractor in full does not, by itself, stop a subcontractor or supplier from recording one. Ask for unconditional lien releases as you pay.

Should the permit be in my name or the contractor's?

If you hired a contractor, CSLB says the contractor should obtain the permits. The permit application has to include the license number, or the reason the applicant is exempt. Signing as an owner-builder takes on the owner-builder duties CSLB describes.

Does this site recommend ADU contractors?

No. There is no contractor list on this site. Check any contractor yourself on CSLB's website.

Sources

California statutes and CSLB pages this guide is based on. Accessed October 20, 2026. Swimming-pool contracts, alarm contracts, and service-and-repair contracts under Bus. & Prof. Code §§7159.10–7159.14 follow extra or different rules and are not restated here.

Check ADU rules for your address