MEP Plans in Spring Valley, CA

Spring Valley project facts we design around

County	San Diego County (unincorporated)
Title 24 climate zone	Climate Zone 10 (with parts in CZ 7), confirmed by ZIP for every project
Electric utility (most addresses)	San Diego Gas & Electric (SDG&E)
Permits issued by	San Diego County Planning & Development Services – Building Division
ADU permits issued, 2021–2025	262
ADU approval timeline	Approve or deny within 60 days of a complete application (state law)

ADU building activity in Spring Valley

San Diego County issued 262 ADU building permits from 2021 through 2025 for addresses in Spring Valley, based on the county's reports to the state. Permits went from 38 in 2021 to 60 in 2025.

2021	2022	2023	2024	2025
38	47	56	61	60

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

Title 24 in Climate Zone 10

• 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%).
• Whole-house fan required (at least 1.5 cfm per square foot of floor area); units of 500 sq ft or less are exempt.
• Cool roof required: steep-sloped roofs need aged solar reflectance 0.2 or higher and thermal emittance 0.75 or higher.
• Solar PV sized by the CEC formula kW = (floor area x 0.627) / 1000 + 1.41; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 622 sq ft or smaller.

Climate Zone 10 requirements in full →

HVAC design for Spring Valley

The California Energy Commission's design-day data for Spring Valley gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 85°F and a winter design temperature of 34°F.

Summer design (1%)	85°F dry bulb / 68°F wet bulb
Winter design (median of extremes)	34°F
Daily temperature range	30°F
Elevation	300 ft

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 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 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.