MEP Plans in Twentynine Palms, CA

Twentynine Palms project facts we design around

County	San Bernardino County
Title 24 climate zone	Climate Zone 14, confirmed by ZIP for every project
Electric utility (most addresses)	Southern California Edison (SCE)
Permit review	The City of Twentynine Palms building department
ADU permits issued, 2021–2025	7 (#408 of 450 cities)
ADU approval timeline	Approve or deny within 60 days of a complete application (state law)

ADU building activity in Twentynine Palms

Twentynine Palms issued 7 ADU building permits from 2021 through 2025, the 408th most among the 450 California cities that reported ADU permits. Permits went from 2 in 2022 to 1 in 2025.

2021	2022	2023	2024	2025
not reported	2	not reported	4	1

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

Title 24 in Climate Zone 14

• Windows: U-factor 0.27 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 0.741) / 1000 + 1.26; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 729 sq ft or smaller.

Climate Zone 14 requirements in full →

HVAC design for Twentynine Palms

The California Energy Commission's design-day data for Twentynine Palms gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 106°F and a winter design temperature of 21°F.

Summer design (1%)	106°F dry bulb / 70°F wet bulb
Winter design (median of extremes)	21°F
Daily temperature range	31°F
Elevation	1,975 ft
Heating degree days	1,973

Cooling governs equipment size here. At 106°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.

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.