MEP Plans in Windsor, CA
Permit-ready mechanical, electrical and plumbing plans for ADUs, garage conversions, additions and single-family homes in Windsor, prepared for plan check at the City of Windsor building department, with Title 24 available in the same order.
Windsor project facts we design around
| County | Sonoma County |
|---|---|
| Title 24 climate zone | Climate Zone 2, confirmed by ZIP for every project |
| Electric utility (most addresses) | Pacific Gas and Electric (PG&E) |
| Permit review | The City of Windsor building department |
| ADU permits issued, 2021–2025 | 49 (#296 of 450 cities) |
| ADU approval timeline | Approve or deny within 60 days of a complete application (state law) |
ADU building activity in Windsor
Windsor issued 49 ADU building permits from 2021 through 2025, the 296th most among the 450 California cities that reported ADU permits. Permits went from 3 in 2021 to 14 in 2025.
| 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|
| 3 | 4 | 10 | 18 | 14 |
Source: California Department of Housing and Community Development, Annual Progress Report data (ADU building permits by year).
Title 24 in Climate Zone 2
- Windows: U-factor 0.27 or lower and solar heat gain coefficient (SHGC) 0.23 or lower, with total window area up to 20% of floor area (west-facing up to 5%).
- Solar PV sized by the CEC formula kW = (floor area x 0.621) / 1000 + 1.22; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 934 sq ft or smaller.
Climate Zone 2 requirements in full →
HVAC design for Windsor
The California Energy Commission's design-day data for Windsor gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 95°F and a winter design temperature of 24°F.
| Summer design (1%) | 95°F dry bulb / 68°F wet bulb |
|---|---|
| Winter design (median of extremes) | 24°F |
| Daily temperature range | 35°F |
| Elevation | 130 ft |
| Heating degree days | 1,249 |
Both seasons matter here. The heat pump is usually sized for the 95°F cooling condition and then checked to confirm it still covers the heating load at 24°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.
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 |
|---|---|---|---|
| Santa Rosa | CZ 2 | Pacific Gas and Electric (PG&E) | 497 |
| Petaluma | CZ 2 | Pacific Gas and Electric (PG&E) | 124 |
| Sebastopol | CZ 2 | Pacific Gas and Electric (PG&E) | 61 |
| Sonoma | CZ 2 | Pacific Gas and Electric (PG&E) | 57 |
| Healdsburg | CZ 2 | City of Healdsburg Electric Utility | 48 |
| Rohnert Park | CZ 2 | Pacific Gas and Electric (PG&E) | 43 |
Guides for Windsor projects
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Start My OrderGeneral guidance, not legal advice. Climate zone and utility are shown for most addresses in Windsor; requirements vary by project. Confirm with the City of Windsor building department.