How to Vet a Contractor Before You Hire (Not After It Goes Wrong)

To vet a contractor, do five things before you sign: look up the license number with your state board, get a certificate of insurance sent from the insurer, call two or three recent customers, make sure the name and address match everywhere, and write a payment schedule that keeps the down payment small. Do these in order. Most bad jobs show a problem at step one or two.

A homeowner on r/DIY described how he nearly made a $4,000 mistake. After a hail storm, a roofer knocked on his door with a quote that looked fine. A neighbor told him to check the license before signing. He found the state lookup confusing, with license types, status codes and expiration dates that vary by state. He got lucky. Then he asked what other people actually check for any job over $1,000.

What people in the thread do

The top answer was about the door-knock itself. One commenter said he would never hire anyone who came to his door after a storm, because it is a red flag. Others agreed they had never bought from a cold caller.

Then came the checklist. One commenter gave the list in a line: verify the license is active and for the right trade, verify general liability and workers’ compensation insurance, and pull permits when required. He also asks for a detailed written scope with the materials listed, and lien waivers tied to payment milestones. He never releases the final payment before the final inspection.

Another commenter asks for an insurance certificate on the standard ACORD form from the contractor’s insurer. He checks that it covers the type of work being done, not just the contractor’s vehicles and equipment. He said he pays at most 30% up front.

A third said talking to past customers and seeing finished work were the most important steps. He added that some of the worst work he had done was by licensed contractors. One took a down payment and left town, and the license was still listed as active.

A fourth described getting three quotes for a concrete job. The most expensive contractor told him he was wrong about what he wanted. The cheapest ignored his wishes. The middle one listened, made suggestions, and took no for an answer. He took 20% up front and offered a milestone payment schedule himself.

One reply gave a warning: in some markets, asking for a written scope or a payment schedule means you get ghosted. That is a fair point. It is also a useful filter.

The vetting checklist

Step	What to do	Red flag
1. License	Get the number and look it up on the state board’s site. Check status, trade and expiration.	No number, or a number that does not match the name
2. Insurance	Ask the contractor’s insurer or broker to send a certificate. Check coverage type, limits, dates and the insured’s name.	A photocopy only, expired dates, or a name that differs from the contract
3. References	Call two or three recent customers. Ask to see finished work.	No references, or only old ones
4. Identity	Check that the name and address match on the license, insurance and contract.	A phone number and no address
5. Contract	Written scope, materials, total price, start and finish dates, change-order terms	Verbal promises
6. Payment	Payment schedule tied to work done; no cash	Pressure to pay now, or payments ahead of the work

1. Check the license

The details vary by state, which is what confused the poster. But the steps are the same. Get the license number from the contractor and look it up on your state contractor board’s site.

California’s CSLB says to verify the license status online or by phone at 1-800-321-CSLB (2752). It requires a license for any home improvement work valued at $500 or more. The California Attorney General says the same $500 line.

Check three things: the status is active, the license class matches the work, and the name matches the person in front of you. The Reddit thread’s warning applies too. A listed license is a starting point and does not prove good work.

2. Check the insurance

A certificate of insurance is a one-page summary from the insurer. Progressive’s guide says to check the limits (its example is $1,000,000 per occurrence for commercial general liability), the effective dates and the insured’s name. The name should match the contractor’s legal business name. The dates should cover the whole project.

Workers’ compensation covers employees hurt on the job and is required in most states, according to Progressive. Ask whether it applies to the people who will be on your property.

Progressive’s advice is to ask for a certificate before work begins, and to be named as an additional insured so that liability shifts away from you in a claim. I would have the insurer or broker send it directly, so you know the policy is current.

3. Call the references

Three bids and three references are the standard advice from the California Attorney General and from CSLB. When you call, ask if the crew showed up when promised, if the price changed, how problems were handled, and whether the final cost matched the quote. Ask to see the work in person if it is nearby.

4. Watch the red flags

CSLB’s list is useful in any state:

• Door-to-door offers of reduced prices for roofing, painting or paving
• Pressure to decide today
• A free inspection that finds alarming problems
• Demands for cash
• A down payment above the legal limit
• Claims that a written contract is not needed

5. Get it in writing

CSLB says the contract should include a specific description of the work, the materials, the total cost and the start and completion dates. Put a payment schedule in it. Do not sign until you understand every term. Ask a friend or relative to read it.

6. Pay for finished work, and get lien waivers

CSLB says not to let payments get ahead of the work and not to pay in cash. It also warns that paying your contractor, or getting a release from your contractor, does not guarantee that subcontractors and suppliers are paid. A claimant is anyone who can file a lien on your property if they go unpaid.

CSLB describes two kinds of waiver. A conditional waiver takes effect only when the payment goes through. An unconditional waiver says the payment has been received. A conditional waiver is the one to collect with each payment, and the unconditional one after the check clears.

Worked example: a $20,000 deck

Use California’s rules as an example. The down payment limit is the lesser of 10% of the price or $1,000. For a $20,000 job, 10% is $2,000, so the limit is $1,000.

A schedule that does not get ahead of the work might be:

Payment	When	Amount
Down payment	At signing	$1,000
Draw 1	Footings inspected	$4,500
Draw 2	Framing complete	$4,500
Draw 3	Decking installed	$4,500
Draw 4	Railings and stairs complete	$4,500
Final	Final inspection passed	$1,000
Total		$20,000

Add it up: $1,000 plus four draws of $4,500 is $19,000, plus $1,000 final is $20,000. If the contractor vanishes after signing, you lose $1,000. With a 50% deposit you would lose $10,000.

In other states the numbers differ. Virginia’s contractor board recommends a down payment of about 10%, or about 30% for jobs with custom-made items. Maryland’s fiscal and policy note for a 2021 bill described its limit as one-third of the contract price at signing. Check your own state’s rules before you agree to anything.

How to decide

Use the checklist as a pass or fail test. A contractor who passes steps one through four and agrees to a written payment schedule is worth a bid. A contractor who dodges any of them is not.

When the answers are close, pick the one who listened. The thread’s best experiences came from contractors who asked questions, offered options and accepted no for an answer. Then compare the price against a calculator estimate such as the Driveway Cost Calculator, Roofing Cost Calculator, Deck Cost Calculator or Fence Cost Calculator. A bid far under the estimate needs an explanation too.

Sources

• What do you actually check before hiring a contractor? (r/DIY thread)
• California CSLB: What You Should Know Before You Hire a Contractor
• California Attorney General: Contractors
• California CSLB: Conditional and Unconditional Waiver and Release Forms
• Progressive Commercial: What is a certificate of insurance for contractors?
• Virginia Board for Contractors: Contractor Statement of Consumer Protections (2025)
• Maryland Department of Legislative Services: Fiscal and Policy Note, HB 395 (2021)