Room additions in Humboldt and Trinity County

Who issues the permit

The Humboldt County building department covers all of unincorporated Humboldt County. It does not cover the cities of Eureka, Arcata, Trinidad, Rio Dell, Fortuna, Ferndale or Blue Lake.

Inside the City of Eureka, the city's own Building Division regulates construction, and building permit applications go through its online permitting platform, OpenGov.

In Trinity County, building permits come from the county's Community Development Department, Building Division, 61 Airport Road, Weaverville.

Sources: Humboldt County: Building Inspection Department; City of Eureka: Building; Trinity County: Building Permit Application (Community Development, Building Division)

Solar

Which newly built homes need a solar power system, where it can go and the exceptions are set out in section 150.1(c)14 of the 2025 California Energy Code, which the Energy Commission explains on its solar page.

Source: California Energy Commission: 2025 Single-Family Solar PV

Grading

For a house in unincorporated Humboldt County, the county asks for a grading plan when the grading is 50 cubic yards or more (not counting the foundation excavation), or when the job triggers the county grading ordinance in any other way.

Source: Humboldt County: Residential (Standard) construction documents

In the coastal zone

Which work in California's coastal zone needs a coastal development permit, and which is exempt, is set out in the Coastal Act, Public Resources Code sections 30600 and 30610.

Sources: California Public Resources Code §30600; California Public Resources Code §30610