New Detached ADU in Santa Ana - One Fixed Price, Permits Handled

Fast, Reliable New Detached ADU Across Santa Ana

A new detached ADU in Santa Ana typically runs $220,000-$380,000 all-in for a custom build from permit set through final inspection, with prefab and modular options starting closer to $180,000. We’re Ellery ADU Studio, and our New Detached ADU team has designed, permitted, and built over 900 ADUs since 2015 - the year California’s ADU laws shifted. Dispatch and scheduling are coordinated from our Los Angeles office, but crews serve Santa Ana locally. We know the tight R1 lots around French Park, the rear-yard garage configurations in Washington Square, and the specific wind and heat loads that inland basin properties face. Call (949) 541-8498 to schedule your free estimate. Every project carries a written price before work starts, per Haven Standard Clause 1.

Call (949) 541-8498

Why Ellery ADU Studio Santa Ana Is Santa Ana’s Preferred New Detached ADU Company

We’ve worked across Santa Ana’s neighborhoods long enough to know that a new detached ADU here is rarely a blank-slate build. The city’s extreme population density and multigenerational household culture mean most “ADU contractors” spend their time legalizing already-occupied garage conversions under SB 13. We do that work too, but our New Detached ADU in Santa Ana practice is specifically for homeowners who want a purpose-built, permitted structure - and need a studio that understands how to site-plan around the garage that’s already sitting in the buildable zone.

Nadia Ellery founded Ellery ADU Studio in 2015 as a design-build practice, not a contractor who subcontracts drawings. The permit set is our core product. Every client receives a written price before any work begins, a documented photo record on every site visit, and the 365-Day Done Right Promise in writing. Our license number appears on every page. Background-checked, uniformed crews handle the build. A live person answers calls 24/7 - no voicemail queue, no callback that doesn’t materialize.

We also offer a Free Second Opinion on any written estimate already in hand. If another studio has quoted your project, we’ll review the scope and the numbers and tell you exactly what’s included, what’s missing, and what questions to ask before you sign.

Our New Detached ADU Services in Santa Ana

Custom Built ADU

Custom builds are what most Santa Ana homeowners picture when they think “detached ADU” - a stick-framed structure designed to match the main house, sized to the rear yard, and built to the specific setback and height limits of your zoning. On Santa Ana’s typical 5,000-6,500 sq ft R1 lots, that rear yard is often narrower than you’d expect once the existing garage, side setbacks, and rear setback are accounted for. We start with a site plan, not a floor plan. The structure follows from what the lot legally allows. A custom 1-bed ADU in Santa Ana typically runs $260,000-$340,000; a 2-bed, $300,000-$380,000. Both include the full permit set, construction, and final inspection.

Prefab ADU Installation

Prefab systems from Dvele, Mighty Buildings, and Plant Prefab can compress the construction timeline by 30-60 days, which matters on Santa Ana lots where weather exposure during framing is a real factor. We specify and coordinate these systems under the same single contract as our custom builds - no separate procurement, no builder-versus-manufacturer disputes. The unit arrives pre-finished or panelized, we handle foundation, utility tie-in, and final inspection. Prefab 1-bed units in Santa Ana typically start around $180,000-$240,000 installed; 2-bed units, $220,000-$300,000. Not every lot fits a prefab module’s dimensions, so we verify site access and crane placement before quoting.

Modular ADU

Modular construction - factory-built to California’s HCD standards, then transported and set - works well on Santa Ana’s flat, grid-patterned streets where truck access is predictable. We’ve coordinated Boxabl and Plant Prefab modules for clients in the Washington Square and Artesia Pilar areas. The key constraint is the existing garage: if it’s occupying the buildable zone, the modular unit may require garage relocation or a different site strategy. We price both options in writing before you commit. Modular 1-bed units in Santa Ana typically run $200,000-$280,000; 2-bed, $250,000-$340,000.

Studio ADU

Studio ADUs - single open room with kitchenette and bath - are the most common detached unit we permit in Santa Ana. At 350-450 sq ft, they fit on lots where a 1-bed would violate setback or open-space requirements. We’ve designed studio ADUs that slide between existing garages and property lines in the French Park historic district, working within the additional design review that area requires. Studio ADUs in Santa Ana typically run $220,000-$280,000 custom, or $180,000-$240,000 prefab. Every quote includes the full permit set, construction, and the documented photo record.

1-Bed & 2-Bed ADU

Separate bedroom units command higher rental income and suit multigenerational use, but they’re also where Santa Ana’s tight-lot math gets unforgiving. A 2-bed ADU needs more linear wall, more window area for egress, and more HVAC capacity - all of which consume the limited footprint. We model the heat load carefully. Santa Ana’s inland basin location means west- and south-facing rear-yard units take the full afternoon sun; we’ve corrected too many competitor installations where the mini-split was sized for coastal conditions and can’t keep up in August. 1-bed units: $260,000-$340,000. 2-bed units: $300,000-$380,000. Both include proper load calculation and equipment specification.

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Trusted Brands We Service in Santa Ana

Ellery ADU Studio specifies and coordinates prefab and modular systems from Dvele, Mighty Buildings, Boxabl, and Plant Prefab within the same single contract as our custom builds. We’re fluent in each manufacturer’s connection details, utility requirements, and lead times - which means your Santa Ana project isn’t delayed because the builder and the module supplier are negotiating who handles the sewer tie-in. We stock common connection hardware and flashing kits locally, so when a Santa Ana wind event exposes a gap at a module-to-foundation joint, we can respond without waiting for a parts shipment from out of state.

Common New Detached ADU Problems We See in Santa Ana Homes

• Unpermitted garage conversions discovered mid-project. On a New Detached ADU in the French Park area, our crew opened a 1940s bungalow’s rear garage wall to tie in utilities and found the original knob-and-tube wiring tapped off a single 20-amp circuit with no subpanel - exactly the DIY setup we see across Santa Ana’s older conversions. We pulled a dedicated 100-amp subpanel, replaced the wiring, and priced the framing repair and waterproofing at the rollup door opening in writing before proceeding. The finished unit cleared inspection and now carries its own panel and meter.
• Santa Ana wind events pressurizing poorly sealed openings. The low-humidity, high-temperature gusts that define this inland basin pressurize structures and expose weatherization gaps in informally converted garages with poorly sealed rollup door openings. On new detached ADUs, we spec continuous air barriers and proper door thresholds that older conversions skip.
• Undersized mini-split sizing on west- or south-facing rear-yard units. Summer afternoon heat loads on these exposures are routinely underestimated by homeowners and even some contractors. We run Manual J load calculations for every Santa Ana project, not rules-of-thumb, and we size equipment for the actual orientation and envelope performance.
• The existing garage occupying the only buildable zone. Most Santa Ana lots are 5,000-6,500 sq ft with a detached single-car garage at the rear. That garage is often the only space legally large enough for an ADU. New detached ADU projects here frequently require garage relocation, garage conversion, or a carefully negotiated setback variance - site planning drives the scope, not the structure.

Pricing for New Detached ADU in Santa Ana, CA

We Also Serve Cities Near Santa Ana

Our crews work throughout central Orange County, including Santa Ana and neighboring Tustin, Orange, Garden Grove, and Costa Mesa. Each city has its own permitting timeline, inspection protocol, and common housing stock - we adjust the permit set and construction sequence accordingly, not copy-paste from one jurisdiction to another.

FAQs - New Detached ADU in Santa Ana