Unincorporated San Mateo County · Climate Zone 3

MEP Plans in Moss Beach, CA

Permit-ready mechanical, electrical and plumbing plans for ADUs, garage conversions, additions and single-family homes in Moss Beach (unincorporated San Mateo County), prepared for plan check at San Mateo County Planning and Building Department – Building, with Title 24 available in the same order.

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Moss Beach project facts we design around

CountySan Mateo County (unincorporated)
Title 24 climate zoneClimate Zone 3, confirmed by ZIP for every project
Electric utility (most addresses)Pacific Gas and Electric (PG&E)
Permits issued bySan Mateo County Planning and Building Department – Building
ADU permits issued, 2021–202517
ADU approval timelineApprove or deny within 60 days of a complete application (state law)

ADU building activity in Moss Beach

San Mateo County issued 17 ADU building permits from 2021 through 2025 for addresses in Moss Beach, based on the county's reports to the state. Permits went from 1 in 2021 to 3 in 2025.

20212022202320242025
13463

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

Title 24 in Climate Zone 3

  • 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 0.628) / 1000 + 1.12; no PV is required if that is under 1.8 kWdc, which for a single ADU works out to about 1,083 sq ft or smaller.

Climate Zone 3 requirements in full →

HVAC design for Moss Beach

The HVAC is sized from a room-by-room Manual J using the outdoor design conditions for the address, in Climate Zone 3's mild Bay Area climate. Load calculation on an older service before you assume a panel upgrade (or skip one).

Electrical service from Pacific Gas and Electric (PG&E)

If the load calculation shows you need a service upgrade, a second meter or a relocated service, Pacific Gas and Electric (PG&E) handles that through its Your Projects portal, separately from the building permit.

ADU electrical service with Pacific Gas and Electric (PG&E) →

Plumbing and sewer

The plumbing plan shows the route, slope and cleanouts of the connection to the existing sewer lateral or septic system. Some Bay Area cities also have private sewer lateral inspection rules, so ask whether your project triggers one.

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.

Nearby places compared

PlaceClimate zoneElectric utilityADU permits 2021–25
San MateoCZ 3Pacific Gas and Electric (PG&E)484
Menlo ParkCZ 3Pacific Gas and Electric (PG&E)398
Redwood CityCZ 3Pacific Gas and Electric (PG&E)354
PacificaCZ 3Pacific Gas and Electric (PG&E)340
HillsboroughCZ 3Pacific Gas and Electric (PG&E)298
South San FranciscoCZ 3Pacific Gas and Electric (PG&E)258

San Mateo County → · All California cities and communities →

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General guidance, not legal advice. Climate zone and utility are shown for most addresses in Moss Beach; requirements vary by project. Confirm with San Mateo County Planning and Building Department – Building.