MEP Plans in Orange County, CA
Permit-ready mechanical, electrical and plumbing plans for ADUs, garage conversions, additions and single-family homes anywhere in Orange County, in its cities and in unincorporated areas, with Title 24 available in the same order.
Orange County project facts we design around
| County seat | Santa Ana |
|---|---|
| Population | 3,170,435 (Census 2024 estimate) |
| Incorporated cities | 34 |
| Unincorporated residents | About 131,266 (4% of the county) |
| Permits in unincorporated areas | OC Public Works – OC Development Services, Building & Safety |
| Title 24 climate zones | CZ 8 (about 70% of residents), CZ 6 (about 30% of residents). Confirmed by ZIP for every project |
| ADU approval timeline | Approve or deny within 60 days of a complete application (state law) |
HVAC design across Orange County
Climate Zone 8: inland climate with hot summers (about 70% of residents)
Summer afternoons regularly push well into the 90s and beyond, so cooling — not heating — sets the equipment size. West-facing glazing, roof insulation and where the ducts run make a large difference to the load. Plan check will expect the Manual J to back up the capacity you show, and the heat pump's electrical load has to be carried through to the panel calculation.
- Cooling-driven Manual J with real window orientation and glazing
- Heat pump and heat pump water heater loads carried into the NEC 220 calc
- Duct location and insulation that match the Title 24 assumptions
Climate Zone 6: coastal, marine-influenced climate (about 30% of residents)
Ocean air keeps summers mild and winters cool rather than cold, so heating and cooling loads are small. The common mistake here is oversizing: a rule-of-thumb unit short-cycles, controls humidity poorly, and wastes panel capacity. A room-by-room Manual J usually supports a compact ducted or ductless heat pump, and in many small units a single well-placed mini-split head does the job.
- Right-size the heat pump from a real Manual J instead of a tonnage guess
- Bath and kitchen exhaust plus whole-unit ventilation sized to ASHRAE 62.2 — tight coastal units trap moisture
- Corrosion-resistant outdoor equipment placement near the ocean
Unincorporated Orange County
Unincorporated communities are permitted by the county, not by a city. County plan check reviews MEP drawings against the same California Mechanical, Electrical and Plumbing Codes and the Title 24 Energy Code as any city, but the submittal checklist, forms and fees are the county's own, so we prepare the set to match. In rural areas, parcels outside a sewer district often rely on a private septic system; adding an ADU can require the county's environmental health division to confirm the system has capacity, and the plumbing plan then shows the connection to the septic tank instead of a sewer lateral.
What's in an Orange County MEP set
- Mechanical: HVAC layout, Manual J load calculation, equipment schedule, exhaust and whole-unit ventilation
- Electrical: power and lighting plan, panel schedule, NEC 220 load calculation, single-line diagram
- Plumbing: supply and DWV layout, fixture units, water heater, gas (if any), sewer or septic connection
- Title 24 (add-on): energy compliance for your address's climate zone, coordinated with the MEP design so the two documents agree
Pricing is flat statewide: ADU plans from $995, full ADU MEP package from $2,295, Title 24 add-on $240. Standard turnaround is 5 business days with two revisions and corrections included.
Orange County cities and communities
| Place | Climate zone | Electric utility |
|---|---|---|
| Anaheim | CZ 8 | Anaheim Public Utilities |
| Brea | CZ 8 | Southern California Edison (SCE) |
| Buena Park | CZ 8 | Southern California Edison (SCE) |
| Capistrano Beach (Dana Point neighborhood) | CZ 6 | San Diego Gas & Electric (SDG&E) |
| Corona del Mar (Newport Beach neighborhood) | CZ 6 | Southern California Edison (SCE) |
| Costa Mesa | CZ 6 | Southern California Edison (SCE) |
| Cypress | CZ 8 | Southern California Edison (SCE) |
| Dana Point | CZ 6 | San Diego Gas & Electric (SDG&E) |
| Fountain Valley | CZ 6 | Southern California Edison (SCE) |
| Fullerton | CZ 8 | Southern California Edison (SCE) |
| Garden Grove | CZ 8, 6 | Southern California Edison (SCE) |
| Huntington Beach | CZ 6 | Southern California Edison (SCE) |
| Irvine | CZ 8 | Southern California Edison (SCE) |
| La Habra | CZ 8 | Southern California Edison (SCE) |
| La Palma | CZ 8 | Southern California Edison (SCE) |
| Laguna Beach | CZ 6 | Southern California Edison (SCE) |
| Laguna Hills | CZ 6 | San Diego Gas & Electric (SDG&E) |
| Laguna Niguel | CZ 6 | San Diego Gas & Electric (SDG&E) |
| Lake Forest | CZ 8 | Southern California Edison (SCE) |
| Los Alamitos | CZ 8 | Southern California Edison (SCE) |
| Midway City (unincorporated) | CZ 6 | Southern California Edison (SCE) |
| Mission Viejo | CZ 8 | Southern California Edison (SCE) |
| Newport Beach | CZ 6 | Southern California Edison (SCE) |
| Orange | CZ 8 | Southern California Edison (SCE) |
| Placentia | CZ 8 | Southern California Edison (SCE) |
| Rancho Santa Margarita | CZ 8 | Southern California Edison (SCE) |
| San Clemente | CZ 6 | San Diego Gas & Electric (SDG&E) |
| San Juan Capistrano | CZ 6 | San Diego Gas & Electric (SDG&E) |
| Santa Ana | CZ 8 | Southern California Edison (SCE) |
| Seal Beach | CZ 6 | Southern California Edison (SCE) |
| Stanton | CZ 8 | Southern California Edison (SCE) |
| Trabuco Canyon (unincorporated) | CZ 8 | Southern California Edison (SCE) |
| Tustin | CZ 8 | Southern California Edison (SCE) |
| Villa Park | CZ 8 | Southern California Edison (SCE) |
| Westminster | CZ 6 | Southern California Edison (SCE) |
| Yorba Linda | CZ 8 | Southern California Edison (SCE) |
Shown for most addresses in each city. We also serve Orange County's other 2 cities and every unincorporated community.
Orange County ADU MEP questions
Who issues building permits for an ADU in unincorporated Orange County?
In unincorporated areas, home to about 131,266 residents (4% of the county), ADU and residential permits go through OC Public Works – OC Development Services, Building & Safety. Inside the county's 34 incorporated cities, that city's own building department reviews the plans instead. We prepare the MEP set for whichever office has jurisdiction over your address.
What Title 24 climate zones are in Orange County?
Orange County spans 2 Title 24 climate zones: CZ 8 (about 70% of residents), CZ 6 (about 30% of residents). Zones follow ZIP-code boundaries, so we confirm the zone from your project address before sizing the HVAC or running the Title 24 report.
Who provides electric service in Orange County?
It depends on the address. In the Orange County places listed on this page, most addresses are served by Anaheim Public Utilities, Southern California Edison (SCE) or San Diego Gas & Electric (SDG&E). We confirm the serving utility for every project, because service upgrades and new meters are requested from the utility, separately from the building permit.
How much do ADU MEP plans cost in Orange County?
Our pricing is flat across California: single-discipline ADU plans start at $995, a full MEP package for an ADU up to 600 SF is $2,295, and a Title 24 report can be added for $240. Residential (single-family) full MEP packages start at $3,495. Standard turnaround is 5 business days, and corrections are included.
How long does ADU approval take in Orange County?
California law requires local agencies, counties included, to approve or deny a complete ADU permit application within 60 days. Incomplete or inconsistent drawings are the most common reason the clock restarts, which is why MEP plans that match the architectural set, and a Title 24 report that matches the MEP design, matter.
Guides for Orange County projects
Ready for permit-ready MEP plans in Orange County?
Upload your architectural plans, get an instant flat price, and receive PDF plans in about 5 business days.
Start My OrderGeneral guidance, not legal advice. Population figures are Census Bureau 2024 estimates; climate zones are from the California Energy Commission's ZIP-code list, weighted by population. Requirements vary by project: confirm with OC Public Works – OC Development Services, Building & Safety or your city's building department.