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California contractor license

Master Roofing Company

Master Roofing Company of Oakland holds California license 921058 (B General Building, C10 Electrical, C39 Roofing). The CSLB file dated Oct 30, 2026 lists it as active.1 It expires Aug 31, 2028.

Doing business as Samjin Construction Inc.

Licensed 18 years, longer than 59% of 87 active Oakland electrical contractors.

Active

Master Roofing Company, Oakland

License
921058
Class
B General Building; C10 Electrical; C39 Roofing
Expires
Aug 31, 2028
Bond
$25,000
Workers' comp
Insured to Jun 1, 2027

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
$25,000Merchants Bonding Company (Mutual), from Aug 15, 2024, continuous
Liability insurance
Not in the CSLB fileCheck with the board
Workers' comp
InsuredState Compensation Insurance Fund, from Jun 1, 2014, to Jun 1, 2027

Who is on this license?

Officer
Diana Y. AuSince Aug 20, 2008
Officer
Nanjoo L. AuSince Aug 20, 2008
Responsible managing officer
Sang C. ChunSince Aug 20, 2008
Responsible managing officer
Soon I. KwonSince Feb 19, 2015
CEO and president
Mason M. AuSince Aug 20, 2008

What work does this license cover?

Issued Aug 20, 2008.

Which other Oakland businesses hold B General Building?

California electrical contractorsGeneral Contractors in OaklandCalifornia 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)