MEP Plans in McKinleyville, CA
Permit-ready mechanical, electrical and plumbing plans for ADUs, garage conversions, additions and single-family homes in McKinleyville (unincorporated Humboldt County), prepared for plan check at Humboldt County Planning and Building Department – Building Division, with Title 24 available in the same order.
McKinleyville project facts we design around
| County | Humboldt County (unincorporated) |
|---|---|
| Title 24 climate zone | Climate Zone 1, confirmed by ZIP for every project |
| Electric utility (most addresses) | Pacific Gas and Electric (PG&E) |
| Permits issued by | Humboldt County Planning and Building Department – Building Division |
| ADU permits issued, 2021–2025 | 40 |
| ADU approval timeline | Approve or deny within 60 days of a complete application (state law) |
ADU building activity in McKinleyville
Humboldt County issued 40 ADU building permits from 2021 through 2025 for addresses in McKinleyville, based on the county's reports to the state. Permits went from 14 in 2021 to 3 in 2025.
| 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|
| 14 | 5 | 11 | 7 | 3 |
Source: California Department of Housing and Community Development, Annual Progress Report data (ADU building permits by year).
Title 24 in Climate Zone 1
- Windows: U-factor 0.27 or lower (no SHGC limit in this zone), with total window area up to 20% of floor area.
- Solar PV sized by the CEC formula kW = (floor area x 0.793) / 1000 + 1.27; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 668 sq ft or smaller.
Climate Zone 1 requirements in full →
HVAC design for McKinleyville
The California Energy Commission's design-day data for McKinleyville gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 68°F and a winter design temperature of 28°F.
| Summer design (1%) | 68°F dry bulb / 59°F wet bulb |
|---|---|
| Winter design (median of extremes) | 28°F |
| Daily temperature range | 11°F |
| Elevation | 33 ft |
| Heating degree days | 1,995 |
Both seasons matter here. The heat pump is usually sized for the 68°F cooling condition and then checked to confirm it still covers the heating load at 28°F.
Electrical service from Pacific Gas and Electric (PG&E)
If the load calculation shows you need a service upgrade, a second meter or a relocated service, Pacific Gas and Electric (PG&E) handles that through its Your Projects portal, separately from the building permit.
ADU electrical service with Pacific Gas and Electric (PG&E) →
Plumbing and sewer
The plumbing plan shows the route, slope and cleanouts of the connection to the existing sewer lateral or septic system.
Pricing is flat statewide: ADU plans from $995, full ADU MEP package from $2,295, Title 24 add-on $240. See what's in a complete ADU MEP set.
Nearby places compared
| Place | Climate zone | Electric utility | ADU permits 2021–25 |
|---|---|---|---|
| Eureka | CZ 1 | Pacific Gas and Electric (PG&E) | 166 |
| Arcata | CZ 1 | Pacific Gas and Electric (PG&E) | 74 |
| Fortuna | CZ 1 | Pacific Gas and Electric (PG&E) | 17 |
| Ferndale | CZ 1 | Pacific Gas and Electric (PG&E) | 13 |
| Blue Lake | CZ 1 | Pacific Gas and Electric (PG&E) | 6 |
| Rio Dell | CZ 1 | Pacific Gas and Electric (PG&E) | 5 |
Guides for McKinleyville projects
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Start My OrderGeneral guidance, not legal advice. Climate zone and utility are shown for most addresses in McKinleyville; requirements vary by project. Confirm with Humboldt County Planning and Building Department – Building Division.