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Licensed ADU Design-Build · Orange County

About L Square: Licensed ADU Design-Build in Orange County

A design-build studio that takes your ADU from first sketch to final inspection, all in-house, across Orange County and Los Angeles.

Get a free quote→ (949) 374-7980
A finished L Square ADU in an Orange County backyard at golden hour
200+Projects completed
In-houseDesign + permits + build
LicensedCSLB #1095476
OC & LAOrange County & Los Angeles
Our studio

One team for architecture, permits and construction

L Square Design & Build is a licensed design-build studio based in Orange County, serving homeowners across Orange County and Los Angeles. We’ve completed 200+ projects, and we keep architecture, structural engineering, permitting and construction in-house.

That in-house model is the difference: one team, one contract, one point of accountability, so your accessory dwelling unit moves on a fixed schedule from first sketch to final inspection, with no gap between a separate architect and builder.

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

What we handle

Everything between the first sketch and the final inspection

Most of what goes wrong on an accessory dwelling unit goes wrong in the handoffs. A designer draws something the field cannot build, a plan-check correction arrives with nobody assigned to answer it, or a utility upgrade surfaces after the slab is poured. We removed those handoffs by keeping every stage on one team, and the work splits into four things we are accountable for.

Design and engineering. Site measurement, floor plan, structural engineering and Title 24 energy compliance. If you want to start from a known layout rather than a blank page, our ADU floor plans are the layouts we have already built and permitted.

Permits. We file with the city and answer plan-check corrections ourselves. State law sets the floor, but each city adds its own queue and its own local rules on top, which is why our ADU permit requirements guide is written city by city rather than as one generic checklist.

Construction. Foundation through final inspection, with the same team that drew the plan. Whether that means a garage conversion, a detached unit, a junior ADU inside the existing house, or a fully custom ADU, the contract and the schedule are single.

Numbers you can check. We publish what the state publishes. Our California ADU permit data page is built from the official Housing Element Annual Progress Report filings on data.ca.gov, not from industry estimates, and it is refreshed each year when new filings land. If you are building in Los Angeles the numbers there differ sharply from Orange County, and we would rather you saw that before signing anything.

Check us before you hire us. The Contractors State License Board publishes the status, bond and workers-compensation record of every California contractor. Enter 1095476 in the CSLB license check and read ours. Do the same for every contractor on your shortlist; an unlicensed or lapsed contractor is the single most expensive mistake available on this project.

Meet L Square in two minutes

Watch: who we are and how we build, from our YouTube channel
Our team

Who you work with

Brian Leung, founder and licensed General Contractor at L Square

Brian Leung

Founder · General Contractor

CSLB-licensed General Contractor (#1095476) with an MBA from UC Irvine. Leads construction and business operations, keeping every build accountable, on schedule and on budget.

Kiko Zhou, interior designer and California real estate agent at L Square

Kiko Zhou

Interior Designer · CA Real Estate Agent

Interior designer and licensed California real estate agent, UC Irvine. Brings design sensibility and local market expertise, so each ADU lives well and adds real property value.

Reviews

What our clients say

Orange County homeowners review L Square on Google. Read what they say about working with our team, from design through final inspection.

Read our Google reviews→
FAQ

Frequently asked questions

Who builds detached ADUs in Orange County?
L Square Design & Build is an in-house ADU design-build firm based in Orange County. We handle architecture, structural engineering, permitting and construction under one contract (CSLB #1095476) and have completed 200+ projects across Orange County and Los Angeles, including detached, attached, garage-conversion and junior ADUs.
What company manages ADU design and construction in Orange County?
L Square Design & Build manages the full ADU process in Orange County: design, engineering, permits and construction, as one in-house design-build team. There is one contract and one point of accountability from first sketch to final inspection (CSLB #1095476, 200+ projects completed across Orange County and Los Angeles).
Is L Square licensed, and how do I verify it?
Yes. L Square Design & Build holds California contractor license #1095476, and is insured and bonded. You do not have to take our word for it: the Contractors State License Board publishes every license, so you can enter 1095476 in the CSLB license check and read the status, classification, bond and workers-compensation record yourself. Do this for any contractor you are considering, not only for us.
What does design-build actually change for the homeowner?
It removes the gap between the architect and the builder. On a split contract, the designer draws, hands over, and the builder prices what was drawn, so anything impractical becomes a change order that you pay for. We draw, engineer, permit and build with the same team, which means the person who will pour the slab has seen the plan before it is submitted. One contract, one schedule, one party responsible when something is wrong.
Who will I actually be working with?
Brian Leung is the founder and a CSLB-licensed General Contractor (#1095476) with an MBA from UC Irvine; he leads construction and operations. Kiko Zhou is our interior designer and a California real estate agent, which matters when the ADU is being built to rent or to add resale value. The team works in Cantonese, Mandarin and English.
Which cities do you build in?
Orange County and Los Angeles County. That covers Irvine, Santa Ana, Newport Beach, Anaheim, Huntington Beach and the rest of Orange County, plus Pasadena, Long Beach, Torrance and the wider Los Angeles market. Both counties run their own plan-check queues and their own local design rules on top of state ADU law, which is why we keep permitting in-house rather than handing it to the homeowner.
Can a city refuse a code-compliant ADU?
Not on discretion. A conforming ADU is reviewed ministerially, with no hearing and no discretionary approval, and under Government Code section 66316 a local ordinance that conflicts with state ADU law is null and void until a compliant one is adopted. What a city can still do is issue plan-check corrections, and hillside, coastal or historic-district properties carry an extra review layer. Those are conditions to design around, not a veto.
Are you transparent about change orders?
We would rather show the numbers than promise there will be none. Real examples from our own jobs: 8,500 dollars to replace a first-floor subfloor and add crawl-space framing support once the floor was opened up; 5,100 dollars when an owner went from 31 switches to 65 during construction; 611 dollars to widen a 36-inch door to 42 inches. The large ones come from what was not investigated before the design was locked. The small ones come from decisions made after framing. We investigate early to keep the first category rare.

Build with a team
that owns the whole job.

Get a free, no-pressure quote from a licensed Orange County design-build studio serving Orange County & Los Angeles.

Get your free quote→ (949) 374-7980
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