ADU in Pomona, CA
Junior ADU & Interior Conversion in Pomona typically runs $85,000-$175,000 all-in, drawings through final inspection, while ADU Site Prep & Utilities ranges from $15,000-$65,000 depending on whether we’re upgrading a 60-amp panel or running a new plumbing lateral across a deep citrus-era lot. We’re Ellery ADU Studio, a design-build practice founded in 2015, and we serve Pomona from our Los Angeles office with crews who know the difference between a Lincoln Park craftsman and a south Pomona ranch house. Call (657) 366-5740 to schedule your free estimate.
Why Pomona Homes Are Different
Pomona’s residential parcels carry the footprint of early-20th-century citrus colonies: unusually deep lots with detached garages set back from alley access. That geometry makes garage-conversion ADUs straightforwardly setback-compliant under state law far more often than in denser San Gabriel Valley cities, but the housing stock itself demands specialized knowledge. Most Pomona homes were built before 1960 - craftsman bungalows, Spanish Colonial Revival cottages, and early post-WWII ranches - and their 60-amp electrical panels, unbolted foundations, and original asbestos roofing or stucco require remediation before Building & Safety will issue permits.
The inland valley climate adds another layer. Summer highs regularly exceed 105°F, 15-20 degrees hotter than coastal LA, so mechanical systems must be oversized and radiant-barrier sheathing is nearly mandatory. Hard water from the Pomona Valley supply accelerates scale in tankless water heaters, making softener pre-plumbing a local best practice our crews build in from the first rough.
Our Main Pomona Services
Pomona homeowners call us most often for these three services, each with its own dedicated page and pricing:
ADU Design & Permitting in Pomona
We produce the permit set as the core product, not an afterthought. For Pomona’s pre-1960 housing stock, that means documenting existing conditions with photos, evaluating alley-accessed garages for separate-address eligibility, and preparing drawings that anticipate the sub-panel upgrades and asbestos abatement Building & Safety will require. Every permit set includes a written price before any work begins. ADU Design & Permitting in Pomona.
Garage Conversion ADU in Pomona
Pomona’s detached garages on alley-accessed lots - especially in Lincoln Park and along South Garey Avenue - offer the cleanest permit path in the city. We evaluate slab thickness, roof structure, and utility routing to determine whether the shell can meet residential code without reconstruction. The conversion is quoted as a single contract covering drawings, permits, and construction. Garage Conversion ADU in Pomona.
New Detached ADU in Pomona
On deep lots where the existing garage is too deteriorated or poorly positioned, we design and build new detached units from foundation to finish. We coordinate prefab systems from brands including Abodu and Cover when the site conditions allow, or stick-build with James Hardie siding for custom footprints. The same single contract covers design, permitting, and construction. New Detached ADU in Pomona.
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 Pomona
Junior ADU & Interior Conversion in Pomona solves two distinct demand problems: multi-generational Latino households needing in-law quarters, and Cal Poly Pomona’s roughly 27,000 students creating a robust off-campus rental market. These conversions work within the existing envelope - no new foundation, no setback fight - but Pomona’s pre-1960 housing stock means we routinely encounter lead paint, ungrounded outlets, and original plaster that must be documented before demolition. We handle Junior ADU & Interior Conversion as a single contract with a written price before any work starts, per Haven Standard Clause 1.
Room-to-ADU Conversion
Signs you need it
You have an underused bedroom or den with a separate exterior door, or you’re splitting a large primary bedroom to create a lockable unit with its own kitchenette and bath.
What it costs in Pomona
Room-to-ADU conversion in Pomona typically runs $85,000-$140,000 all-in, including the permit set, mechanical rough-ins, and final inspection.
How we do it
We document existing conditions with photos, design the partition and utility layout, submit to Pomona Building & Safety, then rough in plumbing and electrical before finishing to match the primary residence.
Interior JADU
Signs you need it
You need a compact, code-minimum unit inside your primary residence for family occupancy or restricted rental, with shared walls and no exterior expansion.
What it costs in Pomona
Interior JADU in Pomona typically runs $75,000-$125,000 all-in, drawings through final inspection, with savings from no foundation work offset by fire-separation and sound-attestation requirements.
How we do it
We evaluate the proposed space for egress window compliance, design the kitchenette and wet bath layout, prepare the JADU-specific permit set, and build to the 500-square-foot maximum with interconnected smoke detection.
What Junior ADU & Interior Conversion Costs in Pomona
| Item | Typical range in Pomona |
|---|---|
| Room-to-ADU conversion | $85,000 - $140,000 |
| Interior JADU | $75,000 - $125,000 |
| Above-garage ADU (if applicable) | $110,000 - $175,000 |
Can a Junior ADU have its own address in Pomona?
No - Junior ADUs share the primary residence’s address and utility meters by code, though we design separate entrances where the floor plan allows. Call (657) 366-5740 for an exact quote - estimates are free.
How long does a room-to-ADU conversion take in Pomona?
Permitting takes 8-14 weeks through Pomona Building & Safety, then construction runs 10-16 weeks depending on asbestos or lead abatement needs. Call (657) 366-5740 for an exact quote - estimates are free.
ADU Site Prep & Utilities in Pomona
ADU Site Prep & Utilities in Pomona addresses the gap between an approved permit set and a buildable site: 60-amp panels that won’t support a second kitchen, clay-heavy soil that needs grading for drainage, and plumbing laterals that must cross 150-foot lots to reach alley-accessed garages. Pomona’s hard water and 105°F summer peaks make utility sizing a local specialty, not a generic calculation. We handle ADU Site Prep & Utilities under the same single contract, with a written price before breaking ground.
Electrical Panel Upgrade
Signs you need it
Your existing panel is 60 or 100 amps, has fused disconnects, or shows scorch marks around breakers.
What it costs in Pomona
Electrical panel upgrade in Pomona typically runs $4,500-$8,500 for a 200-amp service, including SCE coordination and permit.
How we do it
We size the load for the ADU’s HVAC, kitchen, and laundry circuits, coordinate with Southern California Edison for service release, pull the permit, and install the new panel with documented photos at each stage.
Plumbing Lateral
Signs you need it
Your ADU site is more than 75 feet from the main sewer line, or the existing lateral is terracotta, Orangeburg, or known to have root intrusion.
What it costs in Pomona
Plumbing lateral installation in Pomona typically runs $8,000-$18,000 depending on trench length across deep lots and pavement restoration.
How we do it
We camera the existing line, design the trench route to minimize hardscape disruption, pull the permit, and install ABS or PVC with proper bedding and compaction for Pomona’s clay soils.
What ADU Site Prep & Utilities Costs in Pomona
| Item | Typical range in Pomona |
|---|---|
| Electrical panel upgrade | $4,500 - $8,500 |
| Plumbing lateral | $8,000 - $18,000 |
| Foundation and grading | $15,000 - $35,000 |
Does Pomona require a separate water meter for an ADU?
Not for Junior ADUs, but detached and some attached ADUs may need a dedicated meter - we verify with Pomona Public Works during the permit set phase. Call (657) 366-5740 for an exact quote - estimates are free.
Can you upgrade my panel without shutting off power for days?
Most Pomona panel upgrades are completed in one working day with SCE temporary power or same-day reconnection; we coordinate the timing before construction starts. Call (657) 366-5740 for an exact quote - estimates are free.
Brands We Service in Pomona
We specify and coordinate prefab and modular systems from Tuff Shed, James Hardie, Abodu, and Cover - integrating them within our single-contract model so the factory warranty and our 365-Day Done Right Promise operate together. Parts for James Hardie siding and Tuff Shed structures are stocked locally, with typical turnaround under two weeks. our brands
Pricing for ADU in Pomona, CA
| Service | Typical range in Pomona |
|---|---|
| Interior JADU | $75,000 - $125,000 |
| Room-to-ADU conversion | $85,000 - $140,000 |
| Above-garage ADU | $110,000 - $175,000 |
| Electrical panel upgrade | $4,500 - $8,500 |
| Plumbing lateral | $8,000 - $18,000 |
| Foundation and grading | $15,000 - $35,000 |
| Gas line extension | $3,500 - $7,500 |
| Landscaping and hardscape restoration | $5,000 - $15,000 |
Prices in Pomona push higher when we encounter asbestos abatement, lead paint remediation, or soil conditions requiring engineered fill - all common in pre-1960 neighborhoods. Under Haven Standard Clause 1, every project is quoted with a written price before any work begins; no door-side upsells, no scope creep.
Neighborhoods We Serve in Pomona
We work across Pomona’s full residential map, from the historic districts to the post-war tracts. Crews are dispatched from our Los Angeles office with materials staged for same-week starts once permits are released.
- Lincoln Park
- South Garey Avenue corridor
- Mayfair
- Westmont
- Philips Ranch
Service Area - Cities Near Pomona
Our crews serve the full Pomona Valley and adjacent communities, including Diamond Bar, CA to the south, Chino Hills, CA to the southwest, Chino, CA to the west, and Rowland Heights, CA to the northwest. Each city carries its own permit timelines and utility coordination requirements, which we document during the initial site evaluation.
Serving Pomona, CA - Our Local Coverage Area
We’re based in the Pomona 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 Pomona
Initial plan check typically runs 6-10 weeks for complete submittals, with corrections adding 2-4 weeks per cycle. We minimize cycles by submitting photo-documented existing conditions and pre-negotiated variance language where lot coverage is tight.
California law limits HOA prohibition of ADUs, but some Pomona associations impose design guidelines or parking requirements that affect layout; we review CC&Rs during the permit set phase and flag constraints before construction.
Yes - we document every visit with timestamped photos sent to your account, and our background-checked, uniformed crews carry license verification you can confirm with Pomona Building & Safety directly.
Call (657) 366-5740 to schedule your free estimate. Every project receives a written price before work starts, a documented photo record on every visit, and the 365-Day Done Right Promise backed in writing under The Haven Standard.
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 Pomona Customers Say
"Garage conversion finished on the drawings and close to the schedule. They were honest that the sewer connection was the unknown, and it was."
- Arjun D."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.