MEP Plans in Vista, CA

Vista project facts we design around

County	San Diego County
Title 24 climate zone	Climate Zone 7, confirmed by ZIP for every project
Electric utility (most addresses)	San Diego Gas & Electric (SDG&E)
Permit review	The City of Vista building department
ADU permits issued, 2021–2025	475 (#46 of 450 cities)
ADU approval timeline	Approve or deny within 60 days of a complete application (state law)

ADU building activity in Vista

Vista issued 475 ADU building permits from 2021 through 2025, the 46th most among the 450 California cities that reported ADU permits. Permits went from 60 in 2021 to 100 in 2025.

2021	2022	2023	2024	2025
60	79	105	131	100

Source: California Department of Housing and Community Development, Annual Progress Report data (ADU building permits by year).

Title 24 in Climate Zone 7

• Windows: U-factor 0.30 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 0.572) / 1000 + 1.15; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 1,136 sq ft or smaller.

Climate Zone 7 requirements in full →

HVAC design for Vista

The California Energy Commission's design-day data for Vista gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 89°F and a winter design temperature of 30°F.

Summer design (1%)	89°F dry bulb / 68°F wet bulb
Winter design (median of extremes)	30°F
Daily temperature range	16°F
Elevation	510 ft

Both seasons matter here. The heat pump is usually sized for the 89°F cooling condition and then checked to confirm it still covers the heating load at 30°F.

Electrical service from San Diego Gas & Electric (SDG&E)

If the load calculation shows you need a service upgrade, a second meter or a relocated service, San Diego Gas & Electric (SDG&E) handles that through its My Project Center portal, separately from the building permit.

ADU electrical service with San Diego Gas & Electric (SDG&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.