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California contractor license

Carstens Construction Co

Carstens Construction Co of San Mateo holds California license 305427 (B General Building). The CSLB file dated Oct 30, 2026 lists it as active.1 It expires Mar 31, 2028.

Doing business as Carstens Realty.

Licensed 51 years, longer than 96% of 156 active San Mateo general contractors.

Active

Carstens Construction Co, San Mateo

License
305427
Class
B General Building
Expires
Mar 31, 2028
Bond
$25,000
Workers' comp
Exempt

CSLB file dated Oct 30, 2026

From the CSLB file dated Oct 30, 2026. Not a consumer report; check the board before you hire.

Has the board taken action on this license?

None in the CSLB file dated Oct 30, 2026. Confirm with the board: CSLB license check

What bond, insurance and workers' comp are on file?

Bond
$25,000Nationwide Mutual Insurance Company, from Sep 1, 2025, continuous
Liability insurance
Not in the CSLB fileCheck with the board
Workers' comp
Exemptfrom Mar 24, 2026

Who is on this license?

Responsible managing officer
Chris A. CarstensSince May 1, 1990

What work does this license cover?

Issued May 12, 1975.

The workers' comp exemption means the holder told the CSLB it has no employees. If a crew works on your job, ask for a workers' comp certificate.

Which other San Mateo businesses hold B General Building?

General Contractors in San MateoCalifornia general contractors

What should you check before hiring?

What to ask before you hire

  1. Get the license number in writing. The name on the license should match the name on your contract and invoice.
  2. Check the class covers the job. A license for one trade doesn't cover another. California license classes
  3. Ask for a certificate of insurance sent to you by the insurance agent, not handed over by the contractor. How to read a COI
  4. Ask who will be on site. If a crew works on your property, ask for proof of workers' comp. An exemption on file means the contractor told the CSLB it has no employees.
  5. Put it in a written contract: license number, price, start date and payment schedule. Check the license again on the day you sign.

If the license is lapsed

  1. Don't sign or pay a deposit until the CSLB shows the license active again.
  2. Ask the contractor why. For a bond or insurance lapse, ask for proof that the new bond or policy was filed with the CSLB, then check again.
  3. If work has started, hold further payments, keep the contract, receipts and photos, and file a complaint with Contractors State License Board (CSLB).
  4. Check another contractor. California license lookup

Sources

  1. CSLB License Master (cslb.ca.gov, Oct 30, 2026)
  2. Contractors State License Board (CSLB)