ADU rules in Irvine
The key facts first, then what we've learned building there.
The snapshot
Checked October 2026. We re-check every lot against the current code.
Irvine
| Rule | Answer |
|---|---|
| Detached ADU size | Up to 1,200 sq ft |
| Setbacks | 4 ft side and rear |
| Height | 16 ft; 18 ft near transit; 25 ft attached |
| Pre-approved plans | Yes, the Irvine Standard Plan Program |
| HOAs | Nearly every lot is in an HOA: state law stops an HOA from banning ADUs, but it can set reasonable rules |
| HOA review | Architectural review often sets the timeline more than the city does |
| Water and sewer | Irvine Ranch Water District (IRWD) |
| Electricity | SCE |
| Building department | Irvine Community Development, Building & Safety |
What's different here
Irvine's master-planned villages mean nearly every lot has an HOA. We prepare the architectural review package alongside the city permit so neither waits on the other.
The city runs a Standard Plan Program of pre-reviewed designs. We help you choose between one of those and a custom plan.
Many two-story tract homes have a downstairs bedroom and bath that can become a JADU or attached ADU for parents.
Water and sewer come from IRWD, with its own connection process. We request it early.
What applies here
Up to 500 sq ft carved out of the house you have.
Learn moreCities must now keep a set of pre-approved ADU plans.
Learn moreSB 9 lets a single-family lot be split in two, with up to two homes on each.
Learn moreSince January 2025, California lets an existing apartment property add detached ADUs, one for every existing unit up to eight, plus conversions of garages and storage.
Learn morePlans that fit
Ready-drawn plans we adapt to your lot and your city.
Ask about your address
We check the lot against these rules and tell you what fits.