How Ellery ADU Studio Diamond Bar Was Born in Diamond Bar
It was a Tuesday morning in 2015, and we were sitting in the parking lot of the Diamond Bar library, phone pressed to our ear, listening to a homeowner in Walnut describe their third failed permit submission. The architect had blamed the contractor. The contractor had blamed the city. The homeowner was out forty thousand dollars and still had no ADU. We hung up and sat there watching the fog burn off the hills above Grand Avenue. That was the moment.
California’s ADU law had just changed. The permitting queue was the actual product, and nobody was treating it that way. Designers drew things builders couldn’t build. Builders quoted prices that doubled once the foundation was poured. Homeowners were left holding the bag, or worse, holding a half-finished studio in their backyard that the county wouldn’t approve for occupancy.
We called the parent company that afternoon. Ellery ADU Studio had opened in 2015 with a single contract: drawings, permit set, and build, one price, one accountable party. We wanted to bring that model to Diamond Bar because we’d seen what happened without it. We promised ourselves three things that morning in the library parking lot: every homeowner gets the full price in writing before we break ground, every permit submission gets a pre-check by someone who’s actually read the Los Angeles County code, and nobody gets left between two vendors pointing at each other. That was 2015. We’re still keeping those promises in Diamond Bar.
Nadia Ellery’s Personal Connection to the ADU Trade
We didn’t start in ADUs. We started in construction administration, sitting in a trailer behind a commercial site in Pomona, logging change orders that made no sense to us. The smell was diesel and damp plywood. The sound was a radio playing ranchera music through blown speakers. We were twenty-six, carrying a clipboard we barely understood, and every day we watched the same thing: the architect would mark up a drawing, the contractor would price it at triple, and the owner would sign because what choice did they have?
The shift happened on a residential job in Rowland Heights. A homeowner had hired a designer for an ADU, then hired a builder separately, and the two had never spoken until the foundation was out of plumb by eight inches. We were there to document the dispute. The homeowner, a retired teacher, walked us through her backyard and pointed at the concrete she’d already paid for. She didn’t cry. She just said, “I thought someone was in charge of the whole thing.” The concrete smelled like wet chalk. The afternoon sun was hitting the San Gabriel Mountains in a way that made them look close enough to touch. We went home that night and couldn’t sleep.
That’s when we started studying ADU law. The 2015 changes were new then, and most builders were treating them like regular additions. They weren’t. The setbacks were different. The utility tie-ins had their own logic. The fire separation requirements between primary dwelling and ADU caught people constantly. We spent six months in county offices, reading rejected permit sets, learning what failed and why. It felt like learning a language by immersion. The fluorescent lights, the stamp-thump of clerks, the particular silence of a room full of people waiting for numbers to be called.
What gets us out of bed now is the same thing: a homeowner who thinks they’re stuck. The ones who’ve been told their lot is too small, their slope too steep, their easement too restrictive. We’ve sat at kitchen tables in Chino Hills and drawn solutions on napkins. We’ve walked lots in Brea with a fifty-foot tape and found the buildable envelope nobody else had bothered to measure precisely. If we weren’t doing this, we’d probably be teaching. There’s something similar in it: watching someone realize they can do something they thought was closed to them.
The work means something personal because an ADU is never just square footage. It’s the daughter who moves home after graduate school. The parents who need to be close but not in the next room. The rental income that makes the mortgage possible in a city like Diamond Bar. We’re building containers for people’s lives, and we don’t forget that when we’re marking up a roof plan at ten o’clock on a Sunday.
Meet Nadia Ellery - The Person Behind Every Job
Nadia Ellery, Owner and Founder of Ellery ADU Studio Diamond Bar.
We came up through construction administration and permit coordination, not sales or marketing. That matters because our first instinct on any job is to read the code, walk the lot, and understand the constraint before we promise anything. We’ve spent eleven years in the field since 2015, and the training that stuck wasn’t in a classroom - it was the hundred-plus permit corrections we personally logged, the site visits where we learned to spot a bearing wall from the pattern in the drywall screws, the conversations with inspectors who taught us their priorities if we asked respectfully.
What makes us different from a corporate franchise technician: we’re the one who answers when the county has a question about your drainage plan. We’re the one who drives back to the site on Saturday because the homeowner noticed a gap in the siding we need to see for ourselves. Our hobby is hiking the trails above Diamond Bar - the same hills we look at from your backyard while we’re measuring for setbacks. That patience, that willingness to look at the same thing twice, carries over.
Our commitment to you is direct: every decision on your ADU runs through us. Not a rotating project manager. Not an offshore drafting team. Us.
Our Promise to Diamond Bar Homeowners
We operate under the Haven Standard, and we reference it by clause because these aren’t slogans - they’re policies we can show you in writing.
Clause 1: Have it in writing. Before we touch your property, you get a flat price, a written scope of work, and a written warranty. We learned this the hard way. Early in 2015, a homeowner in Covina asked us for a “rough number” and we gave one, thinking we were being helpful. The job changed, the number didn’t, and we ate the difference. Now every price is fixed. If we miss something, that’s our cost, not yours.
Clause 4: Evidence on every job. We photograph what we find. The condition of your soil when we expose it. The existing electrical panel before we touch it. The roof framing we open up. You get these photos, labeled by date, with notes. Not because we expect dispute, but because memory is unreliable and a year-long project deserves a record.
Clause 5: No surprises. No “while we’re in here” upsell. No scope creep. If we find something unexpected - termite damage, an unpermitted addition, a utility line where none was mapped - we stop, document it, and give you a written change order with a new price before we proceed. You sign or you don’t. The choice is yours.
Our Credentials
Every pro working under our name is required to hold the license and insurance their state requires. We are state-licensed. We carry insurance and bonding appropriate to residential construction in California. We have built a strong local reputation across Diamond Bar, Walnut, Rowland Heights, Pomona, Brea, Chino Hills, Covina, San Dimas, Yorba Linda, Montclair, Placentia, and Chino through eleven years of continuous operation since 2015.
What this means for you: when someone enters your property to assess your ADU site, they arrive with verifiable credentials, not a business card and a handshake. When work begins, your investment is protected by coverage you can confirm. When neighbors ask who built your ADU, you can point to a track record in their own community.
Rooted in Diamond Bar
We know the difference between the wind coming through the Pomona Valley gap versus settling over the hills toward Chino Hills State Park. We’ve submitted permits to Los Angeles County that had to account for the specific drainage patterns off the South Hills. We’ve designed ADUs for lots on Golden Springs Drive where the slope requires engineered retaining, and for flat parcels near Sycamore Canyon Park where the constraint was oak tree protection zones. Our hours are Monday through Friday, 7:00 AM to 7:00 PM, and Sunday 7:00 AM to 7:00 PM. Saturday we’re closed. We’re at the Diamond Bar farmers market when it’s running, and we buy our hardware from the same suppliers our neighbors do. This is our community. These are our hills. Your ADU gets designed for this specific place, not a template from somewhere else.
Call (657) 239-4865 to schedule your free estimate. We’ll bring the Haven Standard to your lot, walk it with you, and give you a written price before you decide anything.
Written by Nadia Ellery, Owner at Ellery ADU Studio Diamond Bar, serving Diamond Bar and surrounding communities since 2015.