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Custom ADU

Custom ADUs in Orange County

A backyard home designed around your lot, your family and your budget — not a catalog box.

Get your free quote→ (949) 374-7980
Custom ADU — watercolor illustration on an Orange County lot

A custom ADU is drawn from scratch for your property — its setbacks, sun, access and how you’ll actually use it — so every square foot earns its place. Before choosing a layout, confirm buildable area, privacy goals, utility distance, drainage, site access and whether your target size should stay compact or move toward a larger 1,200 sq ft plan.

Real project examples

Real ADU build examples from the Orange County & Los Angeles area

Browse L Square ADU work across multiple completed examples, including exterior details, interiors and finish inspiration.

View real ADU construction examples
Real ADU build example by L Square Design and Build Completed ADU example from L Square project work Finished ADU project example from L Square Design and Build L Square ADU construction example photo
01

Designed for your lot

We start with your lot’s setbacks, sun path, privacy and access, then shape the unit around them — so it fits the site, protects your main-house views, and makes the most of natural light.

02

Sizes & layouts

From a compact studio to a full 1,200 sq ft ADU, we design for how the space will be used — a rental that maximizes income, or a multigenerational suite that lives like a real home.

03

One team, fixed schedule

Architecture, engineering, permits and our own build crews sit under one contract, so your custom design moves on a fixed schedule from first sketch to move-in — with no architect-versus-builder gaps. Use the Orange County ADU cost guide and permit guide to keep early design ideas tied to real site requirements.

★

Why build with L Square

Design, permits and construction under one roof. L Square is a licensed Orange County design-build team (CSLB #1095476). One contract covers architecture, engineering, city approvals and our own build crews — so your ADU moves on a fixed schedule from first drawing to final inspection, across Orange County and Los Angeles.

01 · Architect-grade design
Every unit is drawn around your lot, light and privacy.
02 · Permit-ready, OC-savvy
We know each city’s ADU rules and clear the approvals for you.
03 · Built once, built right
Our own crews deliver on a fixed schedule, foundation to finishes.

Licensed · Insured · Bonded · CSLB #1095476 · Orange County & Los Angeles

Frequently asked questions

What makes a custom ADU different from a stock plan?
A custom ADU is drawn around the actual lot: setbacks, sun, privacy, utility route, drainage, construction access and the way the unit will be used. Stock plans can be a useful starting point, but they often miss real site conditions like a narrow side yard, existing pool, sewer location, slope, tree protection or neighbor-facing windows. We design the unit so it can pass review and live well, not just look good on paper.
How big should my custom ADU be?
The right size depends on the lot and the goal. A compact studio or one-bedroom may be better for rental return and lower build cost. A larger two-bedroom or near-1,200 sq ft unit can make sense for family housing, long-term flexibility or higher rent. We also check access, open space, privacy, utility capacity and city comments before recommending size, because maximum square footage is not always the smartest square footage.
Can a custom ADU really start around $280 per sq ft?
Some qualifying builds can price from about $280 per sq ft, but only when the site, access, utility routes and finish package support that number. A difficult trench, panel upgrade, fire access issue, structural complexity or high-end finish selection changes the budget. We use per-foot pricing as a starting conversation, then build the real quote from drawings, site conditions, scope and allowances.
Can the ADU match my main house?
Yes. We can match roof pitch, siding, stucco, window style, trim, color and exterior details when the goal is for the ADU to feel original to the property. We can also design a cleaner modern contrast if that fits the lot better. The important part is choosing materials early enough that the design, budget and permit drawings all agree, especially if the property has HOA, coastal or neighborhood design review.
Should I design for rental income or family use?
That decision should happen before layout. Rental units usually need durable finishes, privacy, storage, easy maintenance and a bedroom mix that fits the local tenant pool. Family units may prioritize accessibility, quiet, daylight, connection to the main home and long-term comfort. The same 700 sq ft can be designed two very different ways, so we ask about use before we draw walls.

Building an ADU in your Orange County city

ADU rules vary by city — we handle the specifics for your address. Statewide, California allows ADUs up to about 1,200 sq ft with 4-ft side and rear setbacks (CA HCD); your city may add its own details. For the statewide rules, see the CA HCD ADU Handbook.

Irvine ADU rules Anaheim ADU rules Santa Ana ADU rules Huntington Beach ADU rules ADU cost guide All areas we serve

Ready to start
your ADU?

Get a free, no-pressure quote from a licensed Orange County design-build team — and a plan drawn around your lot.

Get your free quote→ (949) 374-7980
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