Do pre-approved ADU plans still need site-specific MEP work?

Usually some, yes. A pre-approved plan covers the building design, but each property has its own utility connections, orientation and existing electrical service, and programs commonly ask for site-specific documents. Los Angeles County, for example, states that site-specific Title 24 energy calculations are still required with its pre-approved ADU standard plans.

How pre-approved plan programs work

Government Code section 65852.27, added by AB 1332, required local agencies to develop a program for pre-approving ADU plans by January 1, 2025. According to HCD's ADU Handbook, the agency must accept submissions from any party and post pre-approved plans online. It must approve or deny within 30 days an application for a detached ADU that uses a plan pre-approved by that agency or another agency in the state, or a plan identical to a previously approved detached ADU. The plans must be valid within the current code cycle.

What programs still ask for

• Title 24. LA County requires site-specific Title 24 energy calculations with the application. Energy compliance depends on your climate zone and how the unit sits on your lot.
• Site plan and utilities. Santa Barbara's program asks for site-specific materials not reviewed during pre-approval, such as a site plan showing utility connections and meters and the nearest manhole cover elevation.
• Agency clearances. LA County requires approvals from every agency listed on its referral sheet before the permit is issued.
• Fire sprinklers. Santa Barbara notes the ADU must have fire sprinklers if the existing house does, with sprinkler drawings submitted on a separate permit.
• Electrical service. Programs differ on whether the load calculation for your existing panel is part of the pre-approved set or must be added for your site. Check your program's checklist.

Limits on changes

The two programs above both restrict changes. LA County allows the ADU to be oriented in any direction and mirrored, but says the plans cannot be revised. Santa Barbara says plans must be identical to the pre-approved version, any deviation results in rejection, and design changes go through a regular ADU application. Moving a bathroom or switching the specified equipment can take you off the fast track.

Questions to answer before you pick a plan

1. Can your existing electrical service handle the unit, or will you need an upgrade?
2. Where will the sewer lateral and water line connect, and how far do they run?
3. Does the plan's specified equipment fit your climate zone and your utility situation?

What this means for your MEP plans

Read the program's checklist to see which MEP and energy items remain site-specific, and confirm your existing service and sewer connection can serve the unit as drawn. MEP Plans USA prepares Title 24 reports and MEP documents for California ADUs where a program requires site-specific work. See Title 24 reports, climate zones and the ADU permit guide. Programs vary, so confirm with your building department.

Sources: hcd.ca.gov, dpw.lacounty.gov, santabarbaraca.gov.