Building an ADU in Irvine means working inside two approval processes at once: the City of Irvine's plan check and your village's HOA architectural review. ProHome handles both, along with detached ADUs, garage conversions, attached ADUs, and JADUs from first design through final inspection.
Irvine is not a city where you can plan an ADU from the state rulebook alone. Nearly every home sits inside a master-planned village with its own architectural guidelines, and lot sizes vary enormously between the older villages and the newer ones. Getting the type of ADU right for your specific lot is most of the work, and it happens before anyone draws anything.
Full-scope ADU projects from design through final inspection. One licensed contractor managing architecture, permitting, HOA review, and construction.
Standalone backyard units up to 1,200 sq ft with their own bedroom, bathroom, kitchen, and living space. Most viable on the deeper lots in Woodbridge, Turtle Rock, University Park, Northwood, and El Camino Real.
Turning an attached or detached garage into a legal living unit with new insulation, plumbing, electrical, and egress. Often the most practical option in Irvine's newer, tighter-lot villages where a detached build will not fit.
An addition built onto the existing home with its own entrance, kitchen, and bathroom, sharing one or more walls with the main house. Frequently the most cost-effective way to add a self-contained unit.
Up to 500 sq ft converted from space inside the home's existing footprint, usually a bedroom plus a kitchenette and separate entrance. The lowest-cost path to a legal second unit, and the one that triggers the least HOA friction.
Architectural plans, structural engineering, City of Irvine plan check submittal, and the village architectural packet. California's streamlined ADU laws speed the city side; we keep the HOA side moving in parallel.
Grading, utility trenching, and new or upgraded electrical, water, and sewer service, coordinated with the main home's existing systems and with sub-metering if you plan to rent the unit.
Irvine's villages were built across roughly five decades, and that history decides what you can build. It is the first thing we look at.
University Park, Turtle Rock, Woodbridge, Northwood, and El Camino Real date from the late 1960s through the 1980s, and they were laid out with genuinely deep rear yards. These are the Irvine lots where a full detached unit of several hundred square feet or more is often achievable while still clearing setbacks and lot coverage limits. They are also the homes most likely to have a conventional two-car garage in a configuration that converts cleanly, which gives you two viable options to compare rather than one.
Portola Springs, Cypress Village, Eastwood, Stonegate, Orchard Hills, and the Great Park neighborhoods are far denser by design. Yards are compact, lot coverage is often close to maxed out by the original build, and a detached ADU frequently will not pencil. In these villages the realistic paths are a garage conversion or a JADU carved out of the existing footprint. That is not a downgrade: a well-executed JADU with its own entrance and kitchenette does the same job for a family member or a long-term tenant at a fraction of the cost.
Nearly every Irvine home is inside a village association with architectural review, and this is the single biggest difference between building an ADU in Irvine versus most of Orange County. California ADU law prevents an HOA from flatly prohibiting an ADU on a single-family lot, so the association cannot simply say no. What it can do is set reasonable standards on exterior finish, roofing, colors, and placement, and it can slow you down considerably if the submittal is incomplete.
We prepare the architectural packet ourselves, with scaled drawings and material specifications, and we run it at the association while the city plan check is underway rather than sequentially. We also do this work for HOA boards directly, so the format we submit is the format reviewers are looking for.
ADU plans go through the City of Irvine's plan check for structural, electrical, plumbing, and utility approvals. State ADU law imposes shorter review timelines than a conventional addition, which helps, but only if the drawings are right on the first submittal. Correction cycles are where ADU timelines actually go wrong, and avoiding them is the practical value of having one licensed contractor own design, engineering, and submittal instead of stitching three vendors together.
Real ranges before anyone visits. Your lot, your finish level, and your utility situation move these numbers, and we confirm with an itemized written quote.
| ADU Type | Typical Range | Typical Build Time |
|---|---|---|
| Junior ADU (JADU, up to 500 sq ft) | $40,000 to $80,000 | 6 to 10 weeks |
| Garage conversion | $60,000 to $120,000 | 6 to 10 weeks |
| Attached ADU | Scoped per project | Varies with scope |
| Detached ADU (up to 1,200 sq ft) | $150,000 to $300,000+ | 4 to 8 months |
Add 2 to 4 months up front for design and permitting. For the wider picture, read our Orange County ADU guide or try the project estimator.
Irvine homeowners do their research and do not want to manage a contractor. We are built for that client.
Our rating reflects clear scopes, honest pricing, and follow-through. Homeowners who hire us always know where their project stands, because we reach out before they have to ask.
We manage the full ADU plan check with the City of Irvine, including structural, electrical, plumbing, and utility approvals, and we coordinate every inspection through final sign-off.
We prepare complete HOA architectural packets in-house and work with association boards directly. The paperwork that stalls other people's ADU projects is a standard step in ours.
Our office is in Lake Forest, a short drive from any Irvine village. That means faster site visits, faster answers, and punch-list items handled by someone who is genuinely nearby.
ProHome handles every trade in-house.
We serve all of Orange County.
Call us today or request a free on-site estimate. We will tell you which type of ADU actually fits your lot before you spend anything on design.