MEP Plans in Folsom, CA

Folsom project facts we design around

County	Sacramento County
Title 24 climate zone	Climate Zone 12, confirmed by ZIP for every project
Electric utility (most addresses)	Sacramento Municipal Utility District (SMUD)
Permit review	The City of Folsom building department
ADU permits issued, 2021–2025	189 (#137 of 450 cities)
ADU approval timeline	Approve or deny within 60 days of a complete application (state law)

ADU building activity in Folsom

Folsom issued 189 ADU building permits from 2021 through 2025, the 137th most among the 450 California cities that reported ADU permits. Permits went from 43 in 2021 to 23 in 2025.

2021	2022	2023	2024	2025
43	45	33	45	23

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

Title 24 in Climate Zone 12

• 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 0.613) / 1000 + 1.4; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 653 sq ft or smaller.

Climate Zone 12 requirements in full →

HVAC design for Folsom

The California Energy Commission's design-day data for Folsom gives the outdoor conditions a Manual J load calculation uses: a summer design temperature of 99°F and a winter design temperature of 25°F.

Summer design (1%)	99°F dry bulb / 69°F wet bulb
Winter design (median of extremes)	25°F
Daily temperature range	36°F
Elevation	350 ft

Both seasons matter here. The heat pump is usually sized for the 99°F cooling condition and then checked to confirm it still covers the heating load at 25°F.

Electrical service from Sacramento Municipal Utility District (SMUD)

If the load calculation shows you need a service upgrade, a second meter or a relocated service, Sacramento Municipal Utility District (SMUD) handles that through its Design & Construction Services, separately from the building permit.

ADU electrical service with Sacramento Municipal Utility District (SMUD) →

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.