ADU Rules: Arcata vs Eureka
How do adu rules rules compare between Arcata, CA and Eureka, CA?
Arcata and Eureka have similar restriction levels.
Arcata, CA
Humboldt County
Humboldt County permits accessory dwelling units (ADUs) and junior ADUs in any zone allowing single-family or multifamily residential use, with ministerial 60-day approval, 4-foot side/rear setbacks, detached size cap of 1,200 sq ft, attached cap of 50% of the primary residence, and a prohibition on short-term rentals of 30 days or less.
View full Arcata rules →Eureka, CA
Humboldt County
Humboldt County permits accessory dwelling units (ADUs) and junior ADUs in any zone allowing single-family or multifamily residential use, with ministerial 60-day approval, 4-foot side/rear setbacks, detached size cap of 1,200 sq ft, attached cap of 50% of the primary residence, and a prohibition on short-term rentals of 30 days or less.
View full Eureka rules →Key Facts Comparison
| Fact | Arcata | Eureka |
|---|---|---|
| Code Section | Humboldt County Code section 314-69.05 (Inland) / 313-69.05 (Coastal) | Humboldt County Code section 314-69.05 (Inland) / 313-69.05 (Coastal) |
| Maximum detached ADU size | 1,200 sq ft (minimum 150 sq ft) | 1,200 sq ft (minimum 150 sq ft) |
| Maximum attached ADU size | 50% of the primary residence floor area | 50% of the primary residence floor area |
| Minimum side/rear setback | 4 feet (zero for conversions or rebuilds in existing footprint) | 4 feet (zero for conversions or rebuilds in existing footprint) |
| Parking | 1 space per ADU, tandem allowed; multiple statutory exemptions | 1 space per ADU, tandem allowed; multiple statutory exemptions |
| Short-term rental rule | Cannot be rented for terms of 30 days or less (69.05.3.4) | Cannot be rented for terms of 30 days or less (69.05.3.4) |
| Permit timeline | 60-day ministerial action required once application is complete | 60-day ministerial action required once application is complete |
Highlighted rows indicate differences between cities.
Arcata FAQ
Can I build an ADU on my unincorporated Humboldt County property?
Yes, in any zone allowing single-family or multifamily residential use, as long as the lot has or will have a primary dwelling and the ADU meets the 4-foot side/rear setback and 1,200-sq-ft detached size cap. Lots in mapped ADU Special Permit Areas (outside fire districts, near airports, in landslide/flood/tsunami hazard areas, or with inadequate water/sewer) may require a Special Permit.
Can I short-term rent (Airbnb) my Humboldt County ADU?
No. Section 69.05.3.4 of the Inland code states: 'The ADU shall not be rented for periods of 30 days or less.' This is enforced as a zoning condition of the ADU.
How long does Humboldt County have to approve my ADU permit?
Sixty days from the date the completed application is received, if an existing single-family or multifamily dwelling is already on the lot (Section 69.05.2).
Do I need extra parking for an ADU?
One off-street space is required, tandem allowed. The requirement does not apply if the ADU is within a half-mile of public transit, in a historic district, part of an existing structure, in a Housing Opportunity Zone (and under 1,000 sq ft), or where on-street permits are required but not offered to the ADU occupant (Section 69.05.4.6.1).
Eureka FAQ
Can I build an ADU on my unincorporated Humboldt County property?
Yes, in any zone allowing single-family or multifamily residential use, as long as the lot has or will have a primary dwelling and the ADU meets the 4-foot side/rear setback and 1,200-sq-ft detached size cap. Lots in mapped ADU Special Permit Areas (outside fire districts, near airports, in landslide/flood/tsunami hazard areas, or with inadequate water/sewer) may require a Special Permit.
Can I short-term rent (Airbnb) my Humboldt County ADU?
No. Section 69.05.3.4 of the Inland code states: 'The ADU shall not be rented for periods of 30 days or less.' This is enforced as a zoning condition of the ADU.
How long does Humboldt County have to approve my ADU permit?
Sixty days from the date the completed application is received, if an existing single-family or multifamily dwelling is already on the lot (Section 69.05.2).
Do I need extra parking for an ADU?
One off-street space is required, tandem allowed. The requirement does not apply if the ADU is within a half-mile of public transit, in a historic district, part of an existing structure, in a Housing Opportunity Zone (and under 1,000 sq ft), or where on-street permits are required but not offered to the ADU occupant (Section 69.05.4.6.1).
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