ADU in Orange, CA
Junior ADU & Interior Conversion in Orange typically runs $95,000-$175,000 all-in for a room-to-ADU or attached addition, while ADU Site Prep & Utilities adds $18,000-$65,000 depending on whether your 1950s ranch needs a panel upgrade or your Old Towne bungalow needs sewer lateral work. We’re Ellery ADU Studio, a design-build practice that handles drawings, permits, and construction under one contract at one written price. Call (562) 263-3350 to schedule your free estimate.
Why Orange Homes Are Different
Orange’s housing stock splits sharply across eras, and that split changes every ADU decision. The Old Towne Historic District, centered on the Glassell/Chapman traffic circle, contains one of Southern California’s densest concentrations of pre-WWII homes: 1890s-1940s Craftsman bungalows, California Colonials, and Spanish Revival cottages with detached rear garages that are structurally ideal for conversion but sit under a historic overlay. The Historic Preservation Committee requires matched exterior materials, compatible massing, and period-appropriate detailing before the standard ADU permit process begins, typically adding 6-10 weeks.
Outside Old Towne, 1950s-1970s ranch-style tracts dominate toward the eastern and northern edges with attached two-car garages and generous lot depths that accommodate both garage conversions and new detached construction with fewer constraints. The mild Mediterranean climate keeps insulation and mechanical demands modest, but the Santiago Hills corridor borders Very High Fire Hazard Severity Zone territory, where ADU permits trigger ember-resistant vent requirements and defensible-space compliance.
Our Main Orange Services
Orange homeowners contact us most often for these three services:
ADU Design & Permitting in Orange
We produce the full permit set - site plan, floor plans, elevations, structural calcs, and Title 24 energy compliance - as the core product, not an afterthought. In Orange, this means navigating the Historic Preservation Committee’s compatibility checklist for Old Towne properties alongside standard city plan check. ADU Design & Permitting in Orange covers the full process from as-built documentation to issued permit.
Garage Conversion ADU in Orange
Garage conversions in Orange range from alley-served detached structures in Old Towne to attached two-car garages in postwar ranch tracts. Each type faces different setback, fire separation, and access requirements. We assess slab condition, ceiling height, and utility routing before quoting. Garage Conversion ADU in Orange details our full process.
New Detached ADU in Orange
New detached units work well on deeper lots in eastern and northern Orange where the historic overlay does not apply. We handle zoning verification, utility trenching, and foundation design through final inspection. New Detached ADU in Orange explains our design-build approach.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Junior ADU & Interior Conversion in Orange
Junior ADU & Interior Conversion in Orange solves the problem of adding rental income or multigenerational space without building new exterior walls. In Old Towne, we regularly convert underutilized main-house rooms into JADUs with separate entrances from the original porch or alley side; in postwar ranches, attached additions and above-garage units are more common. Junior ADU & Interior Conversion covers our full service statewide. Our crews serve Orange locally, with dispatch coordinated from our Los Angeles office.
Room-to-ADU Conversion
Signs you need it
You have a 250-400 square foot bedroom, den, or rear wing with direct exterior access potential and a separate bathroom or space to add one.
What it costs in Orange
Room-to-ADU conversions in Orange typically run $95,000-$140,000 all-in, including the kitchenette, bathroom rough-in, separate meter or submeter, and permit set.
How we do it
We document existing conditions with a measured as-built, design the new layout to meet JADU or ADU code minimums, produce the full permit set, then build with a documented photo record on every visit.
Above-Garage ADU
Signs you need it
Your garage has unfinished attic space or a structurally sound roof framing system that can accommodate a floor, with ceiling height at the ridge exceeding 14 feet.
What it costs in Orange
Above-garage ADUs in Orange typically run $140,000-$220,000 all-in, including structural reinforcement, stair or exterior access, and full utility extension.
How we do it
We verify joist and foundation capacity with a structural engineer, design the access route and fire separation, then build under our single contract with no designer-builder gap.
What Junior ADU & Interior Conversion Costs in Orange
| Item | Typical range in Orange |
|---|---|
| Room-to-ADU conversion (JADU or ADU) | $95,000 - $140,000 |
| Above-garage ADU | $140,000 - $220,000 |
| Attached addition ADU | $165,000 - $275,000 |
Does a Junior ADU need its own kitchen in Orange?
Yes, a JADU requires a kitchenette with cooking facilities per California state law; the bathroom may be shared with the main dwelling if existing. Call (562) 263-3350 for an exact quote - estimates are free.
Can I convert part of my main house in Old Towne without historic review?
No, interior work that alters windows, doors, or exterior appearance in the Old Towne Historic District triggers Historic Preservation Committee review even for JADUs. Call (562) 263-3350 for an exact quote - estimates are free.
ADU Site Prep & Utilities in Orange
ADU Site Prep & Utilities in Orange addresses the gap between “I have a permit” and “we can break ground.” In Old Towne, 1910s-1920s sewer laterals and undersized electrical panels are routine; in eastern ranch tracts, we often find 100-amp panels and clay sewer lines that won’t support a second dwelling unit. ADU Site Prep & Utilities covers our statewide approach. Our crews serve Orange locally, with dispatch coordinated from our Los Angeles office.
Electrical Panel Upgrade
Signs you need it
Your main panel is rated at 100 amps or less, has no open breaker spaces, or shows evidence of prior homeowner subpanel additions.
What it costs in Orange
Electrical panel upgrades in Orange typically run $4,500-$9,000 for a 200-amp service, including SCE coordination and permit.
How we do it
We verify load calculations for the ADU plus main house, coordinate with Southern California Edison, pull the permit, and install with inspection.
Plumbing Lateral
Signs you need it
Your home has original clay or cast-iron sewer lateral, frequent backups, or the city requires a separate sewer connection for the ADU.
What it costs in Orange
Plumbing lateral replacement or extension in Orange typically runs $8,000-$22,000 depending on trench length, pavement restoration, and city connection fees.
How we do it
We camera the existing line, design the new route with city approval, trench or directional-bore, and test before backfill.
What ADU Site Prep & Utilities Costs in Orange
| Item | Typical range in Orange |
|---|---|
| Electrical panel upgrade | $4,500 - $9,000 |
| Plumbing lateral replacement/extension | $8,000 - $22,000 |
| Foundation and grading (new detached) | $12,000 - $28,000 |
Do I need a separate electric meter for my ADU in Orange?
Not required by state law, but SCE offers favorable solar-NEM treatment with separate meters; we evaluate both options during design. Call (562) 263-3350 for an exact quote - estimates are free.
Will the city of Orange require me to replace my sewer lateral?
Orange Public Works requires lateral replacement if the existing line fails video inspection or if you’re adding a separate connection; voluntary replacement avoids future excavation. Call (562) 263-3350 for an exact quote - estimates are free.
Brands We Service in Orange
We specify and coordinate prefab and modular systems from Plant Prefab, Tuff Shed, and James Hardie within our single-contract model, with parts and assemblies stocked regionally for typical 2-4 week turnaround on standard configurations. our brands
Pricing for ADU in Orange, CA
| Service | Typical range in Orange |
|---|---|
| Room-to-ADU conversion | $95,000 - $140,000 |
| Above-garage ADU | $140,000 - $220,000 |
| Attached addition ADU | $165,000 - $275,000 |
| Electrical panel upgrade | $4,500 - $9,000 |
| Plumbing lateral replacement/extension | $8,000 - $22,000 |
| Foundation and grading (new detached) | $12,000 - $28,000 |
| Gas line extension | $3,500 - $8,500 |
| Landscaping and hardscape restoration | $5,000 - $18,000 |
In Orange, historic overlay review, fire-zone compliance in Santiago Hills, and older utility infrastructure are the three factors that push pricing toward the upper end of these ranges. Under Haven Standard Clause 1, every project is quoted with a written price before any work begins; no call-for-pricing, no change orders without written change order.
Neighborhoods We Serve in Orange
We work across Orange’s full range of housing eras and conditions, from historic districts to postwar tracts. Most Orange properties can be assessed within 48 hours of contact.
- Old Towne Historic District
- Orange Hills / Santiago Hills
- El Modena
- Anaheim Hills border tracts
- East Orange 1950s-1970s ranch neighborhoods
Service Area - Cities Near Orange
Our crews serve Orange locally and regularly work in neighboring communities including Santa Ana, CA, Tustin, CA, Garden Grove, CA, and Irvine, CA. Dispatch and scheduling are coordinated from our Los Angeles office.
Serving Orange, CA - Our Local Coverage Area
We’re based in the Orange area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About ADU in Orange
Standard ADU permits in Orange typically clear in 8-12 weeks; Old Towne Historic District properties add 6-10 weeks for Historic Preservation Committee review before standard plan check begins.
Yes, but with additional requirements: matched exterior materials, compatible massing, and period-appropriate detailing must be approved before the ADU permit process starts.
California law limits HOA prohibition of ADUs, but HOAs may impose reasonable design guidelines; we review CC&Rs during our initial feasibility assessment.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Orange Customers Say
"The rental income has covered the payment since the second month. They were realistic about the numbers rather than optimistic."
- Odette N."Handled the whole planning process. We went to one hearing and that was it."
- Rowena C."They walked us through setbacks and utility capacity before we paid anything, and told us one of our two options was not going to get approved."
- Mireille T.