Washington regulates contractors through the Department of Labor & Industries (L&I), and it's one of the clearest examples on this site of why 'licensed' and 'registered' aren't the same thing. L&I's own data confirms that Electrical Contractor and Plumbing Contractor are genuine, distinct, exam-backed business license types — real tested credentials, not just a business filing.
HVAC and general/roofing contracting work differently in Washington: there's no separate exam-backed license type for either. Instead, businesses doing this work typically hold a general 'Construction Contractor' registration with a self-declared specialty code indicating HVAC or roofing work. That registration confirms the business is legally allowed to operate and meets basic bonding/insurance requirements — it does not mean the state tested them specifically on HVAC or roofing code knowledge the way it does for electrical and plumbing contractors.
This is exactly the licensed-vs-registered distinction this site labels explicitly on every profile: Washington electrical and plumbing listings here are tagged 'Licensed' because L&I's own data confirms a real trade-specific credential behind them; Washington HVAC and roofing listings are tagged 'Registered' for the same reason — accuracy about what the state actually verified, not marketing.
L&I's contractor license data is published as a live, publicly accessible export, refreshed on a recurring schedule, covering all four trades this site tracks for Washington. Status works the same way as elsewhere — active, expired, revoked, or pending — reflecting L&I's own current records.
To verify independently, L&I runs its own contractor lookup tool searchable by business name or license/registration number, and it's worth using it directly before a larger project, particularly for HVAC or roofing work where the registration alone doesn't confirm trade-specific testing the way an electrical or plumbing license does.
Practically, this means: for higher-risk electrical or plumbing work in Washington, a valid license is a strong signal on its own. For HVAC or roofing work, it's worth asking more questions — how many similar jobs the business has completed, references, and whether they carry adequate insurance — since the registration alone doesn't carry the same trade-specific weight.