MEP Plans in Half Moon Bay, CA
Permit-ready mechanical, electrical and plumbing plans for ADUs, garage conversions, additions and single-family homes in Half Moon Bay, prepared for plan check at the City of Half Moon Bay building department, with Title 24 available in the same order.
Half Moon Bay project facts we design around
| County | San Mateo County |
|---|---|
| Title 24 climate zone | Climate Zone 3, confirmed by ZIP for every project |
| Electric utility (most addresses) | Pacific Gas and Electric (PG&E) |
| Permit review | The City of Half Moon Bay building department |
| ADU permits issued, 2021–2025 | 94 (#226 of 450 cities) |
| ADU approval timeline | Approve or deny within 60 days of a complete application (state law) |
ADU building activity in Half Moon Bay
Half Moon Bay issued 94 ADU building permits from 2021 through 2025, the 226th most among the 450 California cities that reported ADU permits. Permits went from 22 in 2021 to 11 in 2025.
| 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|
| 22 | 38 | 14 | 9 | 11 |
Source: California Department of Housing and Community Development, Annual Progress Report data (ADU building permits by year).
Title 24 in Climate Zone 3
- 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 0.628) / 1000 + 1.12; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 1,083 sq ft or smaller.
Climate Zone 3 requirements in full →
HVAC design for Half Moon Bay
The California Energy Commission's design-day data for Half Moon Bay gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 74°F and a winter design temperature of 32°F.
| Summer design (1%) | 74°F dry bulb / 61°F wet bulb |
|---|---|
| Winter design (median of extremes) | 32°F |
| Daily temperature range | 15°F |
| Elevation | 60 ft |
| Heating degree days | 3,843 |
Loads are small in this mild climate, so the common mistake is oversizing. A right-sized heat pump runs longer, quieter cycles and controls humidity better than a rule-of-thumb unit.
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. Some Bay Area cities also have private sewer lateral inspection rules, so ask whether your project triggers one.
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 |
|---|---|---|---|
| San Mateo | CZ 3 | Pacific Gas and Electric (PG&E) | 484 |
| Menlo Park | CZ 3 | Pacific Gas and Electric (PG&E) | 398 |
| Redwood City | CZ 3 | Pacific Gas and Electric (PG&E) | 354 |
| Pacifica | CZ 3 | Pacific Gas and Electric (PG&E) | 340 |
| Hillsborough | CZ 3 | Pacific Gas and Electric (PG&E) | 298 |
| South San Francisco | CZ 3 | Pacific Gas and Electric (PG&E) | 258 |
San Mateo County → · All California cities and communities →
Guides for Half Moon Bay projects
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Start My OrderGeneral guidance, not legal advice. Climate zone and utility are shown for most addresses in Half Moon Bay; requirements vary by project. Confirm with the City of Half Moon Bay building department.