Verify a California C-2 (Insulation and Acoustical) contractor license
domain: cslb.ca.gov · 4 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Use CSLB's "Check A License" tool (cslb.ca.gov/onlineservices/checklicenseII/checklicense.aspx) to look up a license number or business name and confirm active status, classifications held, bond, and any complaint disclosures.
Confirm the C-2 classification specifically appears on the license — C-2 (Insulation and Acoustical Contractor) covers installation of insulating media and preformed architectural acoustical materials for temperature/sound control, distinct from a general B (general building) license.
For bulk/list lookups by classification and county, use CSLB's Public Data Portal (cslb.ca.gov/onlineservices/dataportal) — CSLB posting lists are delivered as PDF (an ADA-compliance change), not CSV/Excel, so plan for PDF text extraction if structured data is needed.
If ongoing structured data is required, order CSLB's monthly update files directly from CSLB rather than relying on third-party scrapers, whose data currency and accuracy CSLB does not guarantee.
Known gotchas
CSLB does not offer a public REST API; "Check A License" and the Data Portal are web tools, and third-party "CSLB API" scraper products are unofficial and unaffiliated with CSLB — evaluate data-freshness risk before relying on them for compliance decisions.
A license can be active/current while lacking the C-2 classification specifically — verify the classification, not just license status, before treating a contractor as authorized to do insulation work.
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