Updated October 2026
Monrovia allows ADUs on residential lots under its own ordinance, but state law sets the floor. Where the city’s code is stricter than state law, state law controls.
The short version
- Monrovia’s ADU rules are in Municipal Code section 17.44.005. The city posts its Council-approved ADU Ordinance 2025-01 online.
- Monrovia offers pre-approved ADU plans, from about 476 sf to 798 sf.
- You file an ADU/JADU application with the Planning Division and a building permit application with the Building Division.
- Rentals must be at least 30 consecutive days.
- State law applies on top: 60-day decision, no impact fees at 750 sf or less, and an 800 sf unit with 4 ft side and rear setbacks must be allowed.
What you can build
- Single-family lot: a converted ADU, a JADU of up to 500 sf inside the house, and a detached ADU of up to 1,200 sf.
- Multifamily lot: conversions of non-living space, plus up to 8 detached ADUs, capped at the number of existing units.
- Height: 16 ft for a detached ADU. State law allows 18 ft near qualifying transit and up to 25 ft for an attached ADU.
The process
- Confirm zoning, setbacks and utilities for your lot.
- Choose a pre-approved plan or a custom design.
- Submit the ADU/JADU application and building permit application together. Fees follow the city’s current fee schedule.
- Answer plan-check corrections, pay fees, pull the permit, build and pass final inspection.
Questions on plan check go to the Building Division at building@monroviaca.gov.
What to watch out for
- Monrovia has hillside areas and historic properties. Both can add review.
- Older lots often need a sewer or electrical upgrade.
- Monrovia’s summary table of ADU standards is still marked “coming soon.” Read the ordinance itself.
How we use it
YDS is based in Monrovia. We’ve designed two local restaurants, Rigo’s Fiesta and Joe’s Pizza, and the Arroyo Elementary Classroom Wing concept. For homeowners, we start with what the lot can hold. Sometimes that’s an ADU. On a larger lot, it may be a small-lot subdivision.
From our portfolio
A long, quiet gable for living and working.
Have a lot in mind?
Send us the address and we’ll tell you what it can hold. Book a free consultation → · Follow @ydsarch on Instagram
