MEP Plans in Mentone, CA

Mentone project facts we design around

County	San Bernardino County (unincorporated)
Title 24 climate zone	Climate Zone 16 (with parts in CZ 10), confirmed by ZIP for every project
Electric utility (most addresses)	Southern California Edison (SCE)
Permits issued by	San Bernardino County Land Use Services – Building & Safety
ADU permits issued, 2021–2025	11
ADU approval timeline	Approve or deny within 60 days of a complete application (state law)

ADU building activity in Mentone

San Bernardino County issued 11 ADU building permits from 2021 through 2025 for addresses in Mentone, based on the county's reports to the state. Permits went from 3 in 2021 to 2 in 2025.

2021	2022	2023	2024	2025
3	1	1	4	2

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

Title 24 in Climate Zone 16

• Windows: U-factor 0.27 or lower (no SHGC limit in this zone), with total window area up to 20% of floor area.
• Solar PV sized by the CEC formula kW = (floor area x 0.59) / 1000 + 1.22; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 983 sq ft or smaller.

Climate Zone 16 requirements in full →

HVAC design for Mentone

The California Energy Commission's design-day data for Mentone gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 101°F and a winter design temperature of 27°F.

Summer design (1%)	101°F dry bulb / 69°F wet bulb
Winter design (median of extremes)	27°F
Daily temperature range	34°F
Elevation	1,700 ft
Heating degree days	741

Cooling governs equipment size here. At 101°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 Southern California Edison (SCE)

If the load calculation shows you need a service upgrade, a second meter or a relocated service, Southern California Edison (SCE) handles that through its Building, Renovation, and Project Planning Portal, separately from the building permit.

ADU electrical service with Southern California Edison (SCE) →

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.