Pre-Approved ADU Plans in Los Angeles County

Three programs in Los Angeles County offer ADU plans that have been reviewed before you file: Los Angeles County’s Pre-Approved ADU Standard Plans Program for unincorporated areas, run by Public Works; the City of Los Angeles’s ADU Standard Plan Program, run by LADBS, for lots inside city limits; and the San Gabriel Valley Council of Governments’ Pre-Approved ADU Plans Program, a set of pre-reviewed plans owned by their designers and offered to its member cities. The County and LADBS plans have cleared the building and structural portion of plan check in their own jurisdictions. The SGVCOG plans were reviewed through that program, and each member city decides what the review counts for. A pre-approved plan saves the cost and time of designing the building and, where the jurisdiction honors it, clearing the building portion of plan check. It does not approve the building on your lot. What is pre-done is the structure. What is left is everything about where it sits.

• A site plan: the unit placed on the lot with setbacks, separation from the house, access, drainage and the easement check.
• Zoning review: the zone, overlays, hillside and fire hazard designations, historic status, and the city’s own ADU ordinance.
• Foundation and soils: the standard plan’s foundation assumes level ground and ordinary soil. A sloped or expansive lot needs a site-specific foundation sheet from a licensed engineer.
• Utilities: water, sewer or septic, electrical service size, gas, and fire sprinklers where the main house has them.
• Energy and fire: the energy documents for the orientation chosen, and fire-rated construction where the unit sits near a property line.
• The submittal itself: the application, the plan check that remains, and the corrections that come back, which are about the lot, not the building.

A plan is pre-approved only where the jurisdiction says so. The County’s plans are for unincorporated County land. LADBS’s are for the City of Los Angeles. The SGVCOG plans are offered to its member cities, which decide how to treat them; Monrovia was one of the ten cities that helped select the designs. In any other jurisdiction the same plan is a regular submittal, and most of the County’s 88 cities have no program at all. Before buying a plan, confirm which jurisdiction the lot is in and what it will honor, because that answer decides whether the plan buys you anything.

• We confirm the jurisdiction and the program, then read the lot: zone, overlays, setbacks, slope, utilities, the garage and any existing structures.
• We choose the plan and orientation that fit, or tell you plainly that the lot needs a custom unit, before any money goes to a plan.
• We prepare the site plan, the zoning sheet, the utility plan and any site-specific foundation sheet, coordinated with a licensed structural engineer.
• We submit and manage the plan check to issuance. Since January 1, 2026, the city has 15 business days to tell you in writing whether an ADU application is complete; it then has 60 days from a complete application to decide.

Does a pre-approved plan skip plan check?

No. A County or LADBS plan skips the building review of the structure in its own jurisdiction; an SGVCOG plan skips whatever the member city has agreed to honor. The site plan, zoning, foundation and utilities are reviewed for your lot like any other application.

Can I use a County pre-approved plan in Pasadena or Monrovia?

Not as a pre-approved plan. A County or LADBS approval is good only in the jurisdiction that issued it, and an SGVCOG plan counts only for what the member city honors. In another city the same set is submitted as a regular plan set.

Can a pre-approved plan go on a sloped lot?

Usually, with a site-specific foundation design. The standard foundation assumes level ground and ordinary soil.

Is a garage conversion a pre-approved plan?

No. Pre-approved plans are new detached units. A conversion is designed around the structure you already have.