Trusted Junior ADU & Interior Conversion for Upland Homeowners
Our Junior ADU & Interior Conversion in Upland typically runs $85,000-$175,000 all-in, drawings through final inspection, with most projects permitted within 8-14 weeks and construction lasting 3-5 months. Ellery ADU Studio has designed, permitted, and built 900+ ADUs since 2015, the year California’s statewide ADU laws began reshaping how Upland homeowners add rentable square footage. Every project starts with a written price before any work begins, per Haven Standard Clause 1. Call (840) 212-3065 to review your floor plan and receive your line-item quote.
Upland’s 1902 founding left a stock of historic homes with large main houses, detached garages, and underutilized basements that the current zoning code treats favorably for Junior ADUs. The city’s location at the foot of the San Gabriel Mountains means many properties slope, creating natural daylight opportunities for basement conversions that flatter terrain cannot match. We’ve worked on Euclid Avenue’s Craftsman bungalows, the Foothill Boulevard corridor’s mid-century ranch homes, and the newer subdivisions north of 16th Street where attached addition ADUs fit neatly against existing structures. Each site demands a permit set that accounts for Upland’s specific fire separation requirements, utility connection rules, and the San Bernardino County flood zone overlays that affect some Foothill-facing properties.
Our home page outlines the full design-build model; this page covers only Junior ADU and interior conversion work in Upland and surrounding San Bernardino County cities.
What Our Junior ADU & Interior Conversion Service Includes
Basement ADU
A basement ADU converts below-grade space into a separate dwelling unit with its own kitchen, bathroom, sleeping area, and exterior entrance. In Upland, this option suits homes on sloped lots common north of Foothill Boulevard, where walk-out basements already have daylight and ventilation potential. Ellery ADU Studio Upland produces a full permit set addressing the California Building Code’s emergency egress window requirements, ceiling height minimums, and moisture barrier specifications that San Bernardino County inspectors enforce strictly. We price basement ADUs in Upland at $95,000-$155,000 all-in, depending on whether the existing slab needs reinforcement and how far the sewer lateral must extend to reach the main house connection.
Above-Garage ADU
An above-garage ADU adds a second story over an existing or rebuilt garage structure, creating a detached unit without consuming additional yard space. Upland’s typical 7,500-square-foot lots in the historic district often lack room for ground-level expansion, making vertical construction the only viable path to a detached rental unit. Ellery ADU Studio Upland engineers these for the lateral loads of a second residential floor, specifies fire-rated assemblies where the garage remains active below, and coordinates with Southern California Edison for separate electric meter installation. Our above-garage ADUs in Upland run $110,000-$175,000, with the wide range reflecting whether the existing foundation and framing can carry the load or require complete replacement.
Room-to-ADU Conversion
A room-to-ADU conversion reconfigures existing interior square footage, typically a large bedroom, den, or unused wing, into a self-contained Junior ADU with efficiency kitchen and separate exterior access. This is often the fastest-permitted path in Upland, as it triggers Junior ADU rather than full ADU standards, reducing parking and setback requirements. Ellery ADU Studio Upland verifies that the proposed space meets the 500-square-foot maximum for JADUs under state law, designs the wet wall routing for plumbing, and ensures the unit has independent climate control per Upland’s energy code amendments. Room-to-ADU conversions in Upland typically cost $85,000-$125,000, with price driven by how far the existing plumbing rough-in sits from the new kitchen and bath location.
Attached Addition ADU
An attached addition ADU extends the primary residence with new construction that shares a wall and meets fire separation standards for a distinct dwelling unit. Upland’s R-1 and R-2 zones permit these where setbacks allow, and we’ve built them along the rear property lines of homes in the San Antonio Heights area where larger lots accommodate rear additions without variance. Ellery ADU Studio Upland produces structural calculations for the shared wall, specifies James Hardie siding to match existing exteriors, and pulls the full permit set including Title 24 energy compliance documentation. Attached additions in Upland range $120,000-$165,000, with foundation type, roof tie-in complexity, and utility trenching length as the main variables.
Interior JADU
An interior JADU, distinct from a full room-to-ADU conversion, operates within the strictest Junior ADU parameters: maximum 500 square feet, contained entirely within the existing footprint, with owner-occupancy required in either the primary unit or the JADU. Upland’s code compliance team reviews these for adequate light and ventilation, and for clear documentation that the JADU will not be separately conveyed. Ellery ADU Studio Upland prepares the owner-occupancy affidavit, the deed restriction for county recording, and the HCD-compliant kitchen layout that satisfies Upland’s building official. Interior JADUs are our most price-predictable Upland projects, typically $85,000-$115,000 with variance driven by electrical panel capacity and HVAC zoning requirements.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Brands We Service for Junior ADU & Interior Conversion
Ellery ADU Studio specifies and coordinates prefab and modular systems within our single-contract design-build model. For Abodu units, we’ve completed site prep and utility tie-ins on three Upland-area projects where the client’s lot geometry favored a factory-built module delivered to a prepared foundation. We handle the structural connection details, the California HCD insignia verification, and the final inspection coordination that turns a delivered box into a permitted dwelling. With James Hardie fiber-cement siding, we specify the HardieZone system appropriate to Upland’s inland climate zone, matching existing home exteriors on attached addition ADUs and ensuring the 30-year substrate warranty transfers to the owner. We’ve also coordinated Tuff Shed structures for studio and office JADUs where the client’s priority was speed and the Upland planning department approved the engineered plans under expedited review.
Whether your project involves Abodu, James Hardie, Tuff Shed, or any other manufacturer, we integrate the brand’s specifications into our permit set and construction contract. The single-contract model means no gap between what the brand’s engineer drew and what our crew builds. If you already have a quote from a prefab supplier, we offer a Free Second Opinion to verify that site prep, utility extension, and permit fees are fully accounted for.
Signs You Need Junior ADU & Interior Conversion Right Now
- Your adult child needs housing but cannot afford Upland’s rental market. A JADU keeps family on the property without the friction of shared living space. We’ve converted ground-floor bedrooms in Upland’s north-end subdivisions for exactly this purpose, with the parent retaining the main house and the JADU generating no rental income but preserving family stability. The permit set includes the owner-occupancy documentation Upland requires.
- You have 400-500 square feet of unused interior space with no current purpose. A formal dining room used twice yearly, a basement storing items worth less than the square footage’s rental value, or a garage housing a car that sits on the driveway. These are the raw material of a JADU. Ellery ADU Studio Upland assesses whether the space meets ceiling height, egress, and ventilation minimums before you commit to design fees.
- Your property tax assessment is rising and you need income to cover it. Upland’s home values have appreciated substantially since 2015, and Proposition 13 limits only the assessed value of existing structures. A JADU adds rental income without triggering full reassessment of the primary residence. Our permit set includes the tax parcel documentation that clarifies this distinction for your records.
- You’ve received a code violation notice for an unpermitted conversion already in place. Upland’s code enforcement division actively inspects rental listings and neighborhood complaints. An unpermitted kitchenette or separate entrance can trigger red-tagging and tenant displacement. We produce as-built drawings, structural verification, and the full permit set to bring existing work into compliance, often without demolition.
- Your sewer lateral or electrical service is at capacity and you’re facing a major utility upgrade anyway. The marginal cost of sizing that upgrade for a future JADU is far lower than returning to trench or re-panel later. We coordinate with Southern California Edison and the Cucamonga Valley Water District on timing, so your utility work serves both the primary residence and the planned unit.
Our Junior ADU & Interior Conversion Process - Step by Step
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Site feasibility and zoning verification. We visit your Upland property, measure existing conditions with laser distance meters, and verify your parcel’s zone, General Plan designation, and any overlay districts within 48 hours. You receive a written feasibility memo stating what type of JADU or interior conversion the property allows, what exceptions apply, and what constraints we see. This step costs nothing and carries no obligation.
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Schematic design and written price. Based on the feasibility memo, we produce two schematic floor plans with square footage, window placement, and wet wall locations. Each schematic carries a line-item written price covering design, permitting, and construction through final inspection. Haven Standard Clause 1 requires this price before you sign; no estimate, no allowance, no “to be determined.” You choose the schematic that fits your budget and goals.
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Permit set production and submission. Our drafters produce the full construction document set: architectural plans, structural calculations, Title 24 energy compliance, and the Upland-specific forms for JADU owner-occupancy affidavit and deed restriction. We submit to Upland’s Community Development Department and track the plan check cycle, responding to corrections without change orders unless you modify the scope. Typical Upland plan check for JADUs runs 4-6 weeks.
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Construction with documented photo record. Our crews work from the permitted drawings, not field decisions. Every site visit generates timestamped, geotagged photographs uploaded to your project portal: demolition progress, rough plumbing pressure tests, electrical panel load calculations, insulation placement, and final finish. You receive this record at project close, not a summary. The 365-Day Done Right Promise applies from the date of final inspection certificate.
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Final inspection and occupancy. We schedule Upland building, fire, and health inspections, correct any punch-list items, and deliver your certificate of occupancy, the recorded deed restriction for JADUs, and the complete as-built drawing set. Your written warranty, Haven Standard Clause 7, activates at this point. The project is not considered complete until you have these documents in hand.
How Much Does Junior ADU & Interior Conversion Cost in Upland?
How much Junior ADU & Interior Conversion costs in Upland depends on project type, existing conditions, and utility infrastructure. These ranges reflect our 2024-2025 project data for San Bernardino County inland cities:
| Project Type | Typical Range (All-In) | Main Price Drivers |
|---|---|---|
| Interior JADU (existing space) | $85,000-$115,000 | Electrical panel upgrade, HVAC zoning, wet wall distance |
| Room-to-ADU conversion | $85,000-$125,000 | Plumbing rough-in location, egress window installation |
| Basement ADU | $95,000-$155,000 | Slab reinforcement, moisture mitigation, sewer lateral extension |
| Attached addition ADU | $120,000-$165,000 | Foundation type, roof tie-in complexity, utility trenching |
| Above-garage ADU | $110,000-$175,000 | Existing structure capacity, fire separation, stair access |
What moves a project to the high end of its range: electrical service upgrades from 100A to 200A, sewer lateral replacement under Upland’s older streets, foundation work on pre-1950 structures with unreinforced masonry, and fire sprinkler requirements triggered by specific lot configurations. What keeps costs controlled: existing space with adequate ceiling height, proximity of plumbing to the proposed kitchen and bath, and electrical panels with spare breaker capacity.
Every Ellery ADU Studio Upland quote is a written price before any work begins. Haven Standard Clause 1 prohibits verbal estimates or “allowance” line items that shift risk to the homeowner. Clause 5, No Surprises, locks the scope at contract signing. If we encounter concealed conditions, we document them with photographs, explain the impact, and seek your written approval before any cost adjustment. The free estimate includes a complete permit fee schedule based on Upland’s current fee schedule, not a placeholder.
To avoid overpaying: obtain at least one competing written quote and bring it to us for a Free Second Opinion. We will identify line items that appear low (permit fees underestimated, no contingency for Title 24 compliance) or high (unnecessary structural work, premium finishes without value justification). This service costs nothing and has no obligation attached.
Junior ADU & Interior Conversion Near Upland - Our Service Area
Ellery ADU Studio Upland serves homeowners throughout the inland San Bernardino and western Riverside County corridor. We maintain active permit relationships with Montclair, Rancho Cucamonga, Ontario, Pomona, Chino, Fontana, Eastvale, Diamond Bar, Chino Hills, Corona, and Anaheim. Typical initial site visits in Upland, Montclair, and Rancho Cucamonga occur within 3-5 business days of your call. For Ontario, Pomona, and Chino, we batch site visits twice weekly. Corona and Anaheim projects coordinate through our Orange County permit liaison. Every project receives the same written price guarantee, documented photo record, and 365-Day Done Right Promise regardless of city.
Serving Upland, CA - Our Local Coverage Area
We’re based in the Upland area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked Questions - Junior ADU & Interior Conversion in Upland
A Junior ADU is a specific California housing type: maximum 500 square feet, contained within the existing primary residence footprint, with owner-occupancy required in either the main unit or the JADU. A full ADU can be up to 1,200 square feet, detached or attached, with no owner-occupancy requirement. In Upland, JADUs face faster permitting and fewer parking and setback rules, making them the practical choice for homeowners who plan to remain on-site.
Most Upland JADU projects move from contract signing to certificate of occupancy in 5-8 months. Design and permitting typically consume 2-3 months, with Upland’s plan check averaging 4-6 weeks for complete JADU submittals. Construction runs 3-5 months depending on weather, material lead times, and inspection scheduling. Ellery ADU Studio Upland does not promise specific completion dates, but we do commit to weekly progress updates and a documented photo record that shows where your project stands. Call (840) 212-3065 for a timeline based on your specific property conditions.
Interior JADUs in Upland typically cost $85,000-$115,000 all-in, from initial drawings through final inspection. Room-to-ADU conversions run $85,000-$125,000, while basement and above-garage projects range higher due to structural and utility work. Every project receives a written price before any work begins, per Haven Standard Clause 1. Call (840) 212-3065 for your line-item quote; estimates are free and carry no obligation.
Yes. Ellery ADU Studio specifies and coordinates prefab systems from Abodu, Cover, Dvele, Mighty Buildings, Boxabl, Plant Prefab, Tuff Shed, and James Hardie within our single-contract model. For JADUs specifically, we’ve used Tuff Shed studio structures where Upland’s planning department approved expedited review, and James Hardie siding systems on attached additions requiring climate-appropriate exterior matching. The brand’s engineering integrates into our permit set; there is no separate contractor managing the prefab relationship. If you have a quote from a prefab supplier, bring it for our Free Second Opinion.
We offer a Free Second Opinion on any written estimate already in hand. Nadia Ellery or a senior project manager will review the scope line by line, identify omissions or inflated allowances, and explain how our written price compares. This service costs nothing and creates no obligation. Many homeowners discover that competing quotes omit permit fees, utility connection costs, or Title 24 compliance work that our all-in pricing includes from the start.
Every project is backed by our 365-Day Done Right Promise: if the finished JADU is not built to the permitted drawings, we make it right, in writing, before construction begins. This is Haven Standard Clause 7. The promise covers workmanship, material installation, and compliance with the approved permit set. It does not cover owner-caused damage or normal wear, but it does ensure that what we build matches what we designed and you approved. You receive the written warranty at final inspection, not upon request.
Gather your property’s assessor parcel number, any existing floor plans or surveys, and a rough idea of your budget range. If you have a written quote from another firm, bring that for our Free Second Opinion. We do not need you to clear furniture or provide access to crawl spaces for the initial feasibility visit. Our laser measurements and zoning verification happen in one appointment, and you receive the written feasibility memo within 48 hours. Call (840) 212-3065 to schedule; a live person answers 24/7.
Schedule Your Junior ADU & Interior Conversion Service in Upland Today
Call (840) 212-3065 to schedule your free feasibility visit and receive a written, line-item price before any work begins. Nadia Ellery and the team at Ellery ADU Studio Upland answer calls live, 24 hours a day. Your estimate includes a complete permit fee schedule, a documented photo record commitment, and the 365-Day Done Right Promise in writing. There is no obligation, no deposit required to receive your quote, and no “call for pricing” - Haven Standard Clause 1 guarantees the price appears on the page and in your hand before you decide.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Upland since 2015.