MEP Plans in Mecca, CA

Mecca project facts we design around

County	Riverside County (unincorporated)
Title 24 climate zone	Climate Zone 15, confirmed by ZIP for every project
Electric utility (most addresses)	Imperial Irrigation District (IID)
Permits issued by	Riverside County Building and Safety Department
ADU permits issued, 2021–2025	5
ADU approval timeline	Approve or deny within 60 days of a complete application (state law)

ADU building activity in Mecca

Riverside County issued 5 ADU building permits from 2021 through 2025 for addresses in Mecca, based on the county's reports to the state. Permits went from 2 in 2021 to 2 in 2025.

2021	2022	2023	2024	2025
2	not reported	not reported	1	2

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

Title 24 in Climate Zone 15

• Windows: U-factor 0.30 or lower and solar heat gain coefficient (SHGC) 0.20 or lower, with total window area up to 20% of floor area (west-facing up to 5%).
• Cool roof required: steep-sloped roofs need aged solar reflectance 0.2 or higher and thermal emittance 0.75 or higher; low-sloped roofs 0.63 / 0.75.
• Solar PV sized by the CEC formula kW = (floor area x 1.56) / 1000 + 1.47; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 212 sq ft or smaller.

Climate Zone 15 requirements in full →

HVAC design for Mecca

The California Energy Commission's design-day data for Mecca gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 110°F and a winter design temperature of 24°F.

Summer design (1%)	110°F dry bulb / 75°F wet bulb
Winter design (median of extremes)	24°F
Daily temperature range	30°F
Elevation	-180 ft
Heating degree days	1,185

Cooling governs equipment size here. At 110°F design conditions, west-facing glass, attic insulation and duct location move the load more than anything else, and the heat pump's electrical load has to be carried into the panel calculation.

Electrical service from Imperial Irrigation District (IID)

If the load calculation shows you need a service upgrade, a second meter or a relocated service, open that request with Imperial Irrigation District (IID) early; utility lead times are often longer than plan check.

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.