Trusted New Detached ADU for Chino Hills Homeowners
Our New Detached ADU cost guide explains why a project in Chino Hills typically runs $280,000-$520,000 all-in, from the first site survey through final inspection, depending on size, finish level, and whether you choose custom stick-built or prefab construction. Ellery ADU Studio has designed, permitted, and built over 900 ADUs since 2015, the year California’s ADU laws fundamentally changed, and every project has started with a written price before any work began. We’re a design-build studio, not a contractor who outsources drawings, which means one contract, one written price, and no designer-versus-builder blame gap when something needs adjusting.
A Chino Hills New Detached ADU presents specific conditions: hillside lots with tiered setbacks, the city’s rigorous design-review process for visible structures, and soil conditions that can shift foundation requirements from standard spread footings to engineered piers. We’ve navigated these variables on dozens of Chino Hills projects, from Sleepy Hollow to Butterfield Ranch to the rolling lots near English Springs Park. Our permit sets are built to survive plan-check rounds, not just satisfy a first-pass glance.
Call (951) 456-4467 to schedule your free estimate. A live person answers 24/7, and we offer a Free Second Opinion on any written estimate you already have in hand.
What Our New Detached ADU Service Includes
Custom Built ADU
A custom built ADU is stick-framed on your property from foundation to finish, designed to your specific site constraints and aesthetic preferences. You need this when your lot has unusual geometry, strict HOA or city design guidelines, or you want materials and layouts that prefab systems don’t offer. At Ellery ADU Studio Chino Hills, we produce the full permit set in-house, coordinate structural engineering for Chino Hills’ seismic zone and hillside ordinances, and build through our own crews, all under the same contract at the same written price established before ground breaks.
Prefab ADU Installation
Prefab ADU installation brings a factory-built module to your site, craned onto a prepared foundation and connected to utilities. This path works well when speed matters and your lot allows truck access for delivery, typically reducing on-site construction time from months to weeks. We specify and coordinate prefab systems from Abodu, Cover, and other manufacturers within our single-contract model, handling site prep, foundation, utility tie-ins, and finish work ourselves so the factory warranty and our 365-Day Done Right Promise operate as one coherent guarantee.
Modular ADU
Modular ADUs are built to the California Building Code in factory sections, then transported and assembled on site, distinct from site-built but more flexible than single-module prefab in size and configuration. This suits Chino Hills homeowners who need a 2-bedroom layout or want to match existing rooflines and siding on a primary residence. Ellery ADU Studio coordinates Dvele and other modular systems, managing the critical interface between factory specifications and local Chino Hills permit requirements, including fire department access and utility connection standards that factory sales teams often underestimate.
Studio ADU
A studio ADU is a single-room detached unit, typically 300-450 square feet, with a kitchenette and full bath, no separate bedroom. It’s the right choice for rental income, home office, or aging-parent occupancy when your budget is constrained or your lot size limits what the city will approve. We’ve permitted and built studio ADUs across Chino Hills, including compact lots in the older neighborhoods near Grand Avenue where setback variances, the extra distance the city requires between structure and property line, demanded creative site planning to maximize usable interior space.
1-Bed & 2-Bed ADU
One-bedroom and two-bedroom detached ADUs range from 500 to 1,200 square feet, with separate sleeping areas, full kitchens, and dedicated living space. These configurations generate stronger rental income and accommodate long-term family housing needs, though they trigger more stringent Chino Hills parking and utility requirements. Our permit sets for 1-bed and 2-bed units in Chino Hills routinely address fire separation distances, egress window sizing, and sewer lateral capacity, the actual pipe capacity from your main line, so you don’t discover a $15,000 utility upgrade after construction starts.
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 New Detached ADU
We specify and coordinate prefab and modular systems from Abodu, Cover, Dvele, Mighty Buildings, Boxabl, Plant Prefab, Tuff Shed, and James Hardie. With Abodu, we’ve completed multiple installations in hillside Chino Hills conditions, managing the transition from factory-built shell to site-finished interior, including the critical waterproofing details at roof-wall junctions that factory manuals assume but don’t always detail for local wind exposure. Our Cover projects have involved the proprietary panel system’s integration with standard California Title 24 energy compliance, a step that trips up contractors who treat prefab as plug-and-play.
James Hardie siding appears on many of our custom builds and prefab coordination projects, not as a default but as a specified material when fire resistance, the actual ASTM E-84 rating that Chino Hills and CalFire-adjacent zones require, makes wood or vinyl untenable. Whether your project involves Abodu, Cover, James Hardie, or any other system, we evaluate it against your site’s specific conditions and the city’s actual permit checklist, not the manufacturer’s marketing claims. Our license number appears on every page, verified, not just claimed.
Before
AfterSigns You Need New Detached ADU Right Now
- Your adult child needs housing but the market is unworkable. Chino Hills rents for a 1-bedroom apartment regularly exceed $2,200 monthly, and the vacancy rate stays tight. A detached ADU converts that expense into equity on your property, with rental income that can offset your mortgage or provide below-market family housing without the friction of cohabitation in your primary residence.
- You’re carrying a mortgage rate from 2022-2023 and need income to stabilize payments. Many Chino Hills homeowners bought at peak pricing with rates above 6%. A studio or 1-bedroom ADU generating $1,800-$2,500 monthly in rental income materially changes your debt-to-income picture, and California’s ADU-friendly legislation means cities can’t block permits on owner-occupied lots that meet basic standards.
- Aging parents need proximity without loss of independence. The 2-bedroom ADU configuration allows couples to remain together with kitchen, bath, and living space separate from the main house. We’ve built these specifically for multigenerational families in Chino Hills’ 55+ adjacent neighborhoods, where the alternative is assisted living at $5,000+ monthly.
- Your lot has unused space that’s deteriorating into liability. Steep slopes, poor drainage, or unmaintained areas behind the garage become erosion and fire hazards in Chino Hills’ dry seasons. A properly engineered detached ADU with graded drainage and hardscape converts liability into producing asset, with the site work required for construction solving the underlying maintenance problem.
- You’ve received a written estimate that feels incomplete or vague. Line items like “allowance for unforeseen conditions” or “TBD upon permit approval” are warning signs. Under Haven Standard Clause 1, our written price covers the full scope, and our Free Second Opinion will identify what’s missing in any estimate you already have.
Our New Detached ADU Process - Step by Step
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Site Survey & Feasibility Study. We measure your lot, document existing structures, and verify setbacks, utility locations, and access constraints against Chino Hills’ municipal code. You receive a documented photo record of existing conditions, not a summary of how it looked, and a written feasibility report identifying any variance applications or utility upgrades needed before design begins.
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Design & Permit Set Development. Our architects produce construction drawings, structural calculations, and energy compliance documentation in-house. The permit set is the core product, not an afterthought, and we submit to Chino Hills planning and building departments ourselves, responding to plan-check comments directly rather than passing them through you as a project-management exercise.
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Written Price & Contract. Once the permit set is complete and we’ve received preliminary feedback from the city, we deliver a written price covering design, permitting, construction, and site work. Haven Standard Clause 1 locks this price at signing. No change orders for scope we’ve already identified, no door-side upsells when selections feel pressured.
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Permit Approval & Pre-Construction. We pull permits, schedule inspections in sequence, and prepare your site, including any grading, utility trenching, or foundation work. Our crews are background-checked and uniformed, and the project manager assigned to your build is the same person who reviewed your permit set, eliminating the handoff gap that derails most projects.
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Construction, Inspection & Close-Out. We build to the permitted drawings, with a documented photo record on every visit showing what was found and what was done. Final inspection passed, certificate of occupancy issued, and your 365-Day Done Right Promise activated in writing. If the finished ADU is not built to the permitted drawings, we make it right, documented, not merely promised verbally.
How Much Does New Detached ADU Cost in Chino Hills?
A typical studio ADU in Chino Hills runs $280,000-$350,000 all-in, drawings through final inspection. A 1-bedroom unit typically ranges $320,000-$420,000, and a 2-bedroom detached ADU with full kitchen and laundry runs $400,000-$520,000. Prefab and modular systems can reduce these figures by 10-20% on the construction portion, though site prep, foundation, and utility costs remain consistent across methods.
| ADU Type | Size Range | Typical All-In Cost (Chino Hills) |
|---|---|---|
| Studio ADU | 300-450 sq ft | $280,000-$350,000 |
| 1-Bedroom ADU | 500-750 sq ft | $320,000-$420,000 |
| 2-Bedroom ADU | 800-1,200 sq ft | $400,000-$520,000 |
| Custom Built (premium finishes) | Varies | Add 15-25% to base range |
| Prefab/Modular (installed) | Varies | Base range less 10-20% on construction |
What moves the price: hillside conditions requiring engineered foundations, sewer lateral upgrades when the existing line lacks capacity, fire-resistant materials in CalFire-adjacent zones, and finish selections for flooring, cabinetry, and fixtures. What doesn’t move the price once signed: our scope. Under Haven Standard Clause 5 (No Surprises), the line items are locked. The only price adjustments come from owner-requested changes, documented in writing before execution.
How to avoid overpaying: compare complete permit sets, not just square-footage bids. A low initial estimate that omits structural engineering, Title 24 energy documentation, or utility connection fees will grow. Our free estimate includes every line item we can identify from your site’s actual conditions. Call (951) 456-4467 to schedule yours.
New Detached ADU Near Chino Hills - Our Service Area
We design, permit, and build detached ADUs throughout the Chino Hills area and surrounding communities, typically with initial site surveys scheduled within a week of contact. Our active project zones include New Detached ADU in Chino, New Detached ADU in Yorba Linda, Anaheim, Diamond Bar, Pomona, Eastvale, Montclair, Ontario, Rowland Heights, Corona, and Upland. Response times vary by current permit submission volume, but our Chino Hills-based team knows the specific plan-check preferences of each city’s building department, from Chino Hills’ design-review requirements to Ontario’s utility coordination protocols.
Whether your lot sits on the flat ranch-style parcels near Chino Hills Parkway or the steeper grades of the northern hills, we’ve likely evaluated similar conditions. Our home page lists additional service details, and we welcome questions about your specific site before any commitment.
Serving Chino Hills, CA - Our Local Coverage Area
We’re based in the Chino Hills area and know this community well, and we also handle Pomona New Detached ADU projects nearby. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked Questions - New Detached ADU in Chino Hills
A new detached ADU is a separate, self-contained residential unit built from the ground up on your property, not connected to your main house, with its own foundation, walls, roof, kitchen, bath, and utility connections. In Chino Hills, these range from compact studios to 2-bedroom dwellings up to 1,200 square feet, subject to your lot size and zoning; we also build Diamond Bar New Detached ADU units with similar specifications. Ellery ADU Studio handles the full sequence: feasibility study, permit set, construction, and final inspection, under one contract at one written price.
A typical new detached ADU in Chino Hills takes 12-18 months from signed contract to certificate of occupancy, with 4-6 months for design and permitting and 8-12 months for construction. Prefab and modular systems can compress the construction phase to 4-6 months, though permitting and site prep timelines remain similar. Call (951) 456-4467 for a project timeline based on your specific site and city backlog.
Studio ADUs typically run $280,000-$350,000, 1-bedroom units $320,000-$420,000, and 2-bedroom units $400,000-$520,000, all-in from drawings through final inspection. Hillside lots, utility upgrades, and premium finishes move costs toward the upper end. Every Ellery ADU Studio project starts with a written price before any work begins, per Haven Standard Clause 1. Call (951) 456-4467 for an exact quote on your site, estimates are free.
Yes. We specify and coordinate Abodu, Cover, Dvele, Mighty Buildings, Boxabl, Plant Prefab, Tuff Shed, and James Hardie systems, integrating factory specifications with Chino Hills permit requirements and site conditions. Our single-contract model covers factory coordination, site prep, installation, and finish work, so warranty coverage and our 365-Day Done Right Promise operate without gaps. Call (951) 456-4467 to discuss which system suits your lot and budget.
ADU construction is planned work, not emergency service, and we do not promise same-day dispatch or overnight response for new detached ADU inquiries. Our live person answers calls 24/7 to schedule your free estimate, discuss feasibility, or provide a Free Second Opinion on an existing estimate. For actual emergencies affecting existing structures, we can refer you to appropriate trades.
Every new detached ADU includes our 365-Day Done Right Promise in writing: if the finished unit is not built to the permitted drawings, we make it right. This covers structural, mechanical, and finish elements we installed. Factory components from prefab or modular systems carry their manufacturer’s warranty, which we coordinate with our own coverage so you’re not navigating between two companies. The promise is activated at final inspection, documented, not verbal.
Gather your property survey or plot plan, recent utility bills, and any HOA guidelines if applicable. Note your priorities: rental income, family housing, home office, or future sale value. We’ll photograph existing conditions, measure setbacks, and identify utility locations during our site survey. There’s no preparation required beyond access to your property and a clear sense of your goals. Call (951) 456-4467 to schedule your free estimate, estimates are free and come with a written price before any work starts.
Schedule Your New Detached ADU Service in Chino Hills Today
Call (951) 456-4467 to schedule your free estimate. A live person answers 24/7. You’ll receive a written price before any work begins, per Haven Standard Clause 1, and a Free Second Opinion if you already have an estimate in hand. Nadia Ellery and the team at Ellery ADU Studio Chino Hills have designed, permitted, and built over 900 ADUs since 2015. Every project gets a documented photo record, a locked scope, and our 365-Day Done Right Promise in writing.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Chino Hills since 2015.