Best ADU Builders in Los Angeles, New York, and Chicago: 2026 Guide

Affiliate Disclosure: Blueprint may earn a commission from partners linked in this guide. This doesn't affect our recommendations or editorial independence. We only feature builders with verified track records.

Quick Answer: The best ADU builders in 2026 vary by city. In Los Angeles, Villa Homes and US Modular lead the pack with full turnkey services. In New York, Regulus Construction handles the notoriously complex permitting landscape. Chicago's ADU market is newer but growing fast after the city lifted its 1957 ban in 2020. Expect to pay $150,000–$350,000+ depending on your city, unit size, and build type. Start by getting quotes from at least three licensed contractors in your metro area.

Accessory dwelling units are no longer a California curiosity. They've gone nationwide. And if you're in Los Angeles, New York, or Chicago — three of the largest and most complex housing markets in the country — finding the right ADU builder isn't just important. It's the difference between a smooth 8-month project and a 2-year nightmare.

The ADU construction market hit $8.4 billion in 2025, according to Freddie Mac's housing analysis, and projections put it north of $12 billion by 2028. The demand is real. But so are the headaches: permitting bottlenecks, contractor backlogs, and wildly different regulations across cities and states.

This guide breaks down the best ADU builders in each of these three metros, what they charge, how to vet them, and what you need to know before signing a contract. No fluff. Just the builders, the numbers, and the process.

Why These Three Cities? The ADU Landscape in LA, NYC, and Chicago

Each of these cities occupies a completely different place on the ADU adoption curve. Understanding where your city stands saves you months of confusion.

Los Angeles is the undisputed ADU capital of America. The city issued over 25,000 ADU permits between 2017 and 2025, more than any other municipality in the country. California's aggressive state legislation — AB 68, SB 9, AB 2221 — has systematically removed barriers. Single-family lots can now add up to two ADUs (one attached or detached, plus one junior ADU). The permitting process, while still bureaucratic, is at least well-documented. Dozens of experienced builders compete for your business, which means better pricing and faster timelines.

New York is the opposite story. ADU legalization only took effect in January 2024 under Local Law 156, and the city is still working out implementation details. The five boroughs each present unique zoning challenges. Basement conversions dominate the conversation, but detached ADUs are gaining traction in Queens and Staten Island. The contractor pool with genuine ADU expertise is smaller, which means you need to be pickier. Costs run 20–40% higher than the national average due to labor rates and regulatory complexity.

Chicago sits somewhere in between. The city reversed its 57-year ban on ADUs in 2020 with a pilot program covering five wards. By 2023, the program expanded citywide. But construction volume remains low — fewer than 300 ADU permits issued through 2025 — which means the builder ecosystem is still maturing. The upside? Chicago's lower labor and material costs make ADUs more financially accessible than in either LA or New York.

The common thread: all three cities are experiencing housing shortages that ADUs can partially address. Los Angeles needs an estimated 500,000+ housing units, New York's vacancy rate sits below 2%, and Chicago's affordable housing gap continues to widen in desirable neighborhoods. ADUs aren't a silver bullet, but they're one of the few solutions homeowners can actually control.

Before diving into specific builders, you should understand how much an ADU costs in 2026 — the numbers vary dramatically by market.

Best ADU Builders in Los Angeles (2026)

Los Angeles has the deepest bench of ADU contractors in the country. That's the good news. The bad news is that depth makes choosing one harder. Here are the builders that consistently deliver quality work on schedule and within budget.

Villa Homes

Villa Homes has become synonymous with ADU construction in Southern California. They offer a full turnkey experience — from architectural design and permitting to construction and final inspection. What sets Villa apart is their technology-forward approach: they use proprietary project management software that gives homeowners real-time visibility into construction progress, permitting status, and budget tracking.

Villa specializes in both detached ADUs and garage conversions across Los Angeles County. Their pricing typically starts around $180,000 for a studio unit and scales up to $350,000+ for larger two-bedroom designs. Timelines average 8–12 months from contract to move-in, which is competitive for the LA market. They handle all permitting directly, which is a significant value-add given LA's notoriously slow Department of Building and Safety.

US Modular Inc.

US Modular takes a different approach: factory-built modular ADUs that are manufactured off-site and craned into position. This method dramatically reduces on-site construction time. Where a traditional stick-built ADU might take 6–8 months of on-site work, US Modular can complete the on-site phase in as little as 4–6 weeks.

Their modular units start around $160,000 for a one-bedroom and go up to $300,000+ for custom configurations. The tradeoff is less design flexibility compared to site-built options, but their standard floor plans are well-thought-out and cover most homeowner needs. They're particularly strong for homeowners who want minimal disruption to their daily routine during construction.

For a deeper comparison between prefab and custom builds, check out our ADU vs. tiny home breakdown.

AP Remodeling Inc.

AP Remodeling has built a strong reputation as one of LA's top ADU-focused general contractors. They specialize in ground-up ADU construction and garage conversions, with a portfolio that spans Los Angeles, the San Fernando Valley, and the Westside. Their Yelp and Houzz reviews consistently land in the 4.8–5.0 range.

What makes AP Remodeling stand out is their attention to finish quality. Many ADU builders treat accessory units as budget construction — lower-grade finishes, basic fixtures, minimal landscaping. AP treats each ADU like a custom home build, which shows in the final product. Pricing runs $200–$350 per square foot depending on complexity and finishes.

Go ADU Construction

Go ADU is a specialist — they do ADUs and nothing else. That singular focus means they've streamlined their process in ways general contractors can't match. They handle garage conversions, detached new construction, attached ADUs, and junior ADUs (JADUs). Their website features a cost calculator that gives homeowners a rough estimate before the first phone call, which is a nice transparency touch.

Go ADU's sweet spot is the 400–800 square foot range, with most projects coming in between $170,000 and $280,000. They assign a dedicated project manager to each build, and their average permit-to-completion timeline runs 7–10 months.

CALI ADU

With 20+ years of construction experience and over 100 ADU projects completed, CALI ADU brings deep institutional knowledge to the table. They serve all of Los Angeles County and have particular strength in navigating the permitting process for hillside lots and properties in historic preservation overlay zones — two scenarios that trip up less experienced builders.

AFFILIATE_CTA: Ready to compare ADU builders in Los Angeles? Get free quotes from top-rated local contractors and save thousands on your project.

Best ADU Builders in New York (2026)

New York's ADU market is younger and more complex than LA's. The regulatory framework is still evolving, and the construction environment — tight lots, older homes, union labor requirements in some areas — adds layers of difficulty. These builders have proven they can navigate it.

Regulus Construction

Regulus Construction has positioned itself as one of New York's go-to ADU contractors since legalization. Based in Brooklyn, they serve all five boroughs with a focus on basement ADU conversions and detached backyard units in Queens and Staten Island.

Regulus brings something critical to the NYC market: deep familiarity with the Department of Buildings (DOB) process. New York's permitting system is labyrinthine. Regulus has dedicated permit expediters on staff and relationships with DOB examiners that can shave weeks off the approval timeline. Their projects typically start at $220,000 and can exceed $400,000 for larger units in Manhattan-adjacent areas.

Their specialty is basement conversions that comply with Local Law 156 requirements — including minimum ceiling heights, egress windows, waterproofing standards, and separate utility metering. These conversions are the most common ADU type in NYC, accounting for roughly 65% of all ADU applications in the city's first year of legalization.

Bolster

Bolster isn't an ADU-only builder, but their renovation expertise across New York City makes them a strong contender for ADU projects. They use a transparent pricing model — no change orders, guaranteed maximum price — which addresses one of the biggest pain points in NYC construction. Their technology platform provides detailed cost breakdowns before construction begins.

Bolster's ADU projects typically run $250–$450 per square foot, reflecting New York's higher labor and material costs. They're best suited for homeowners who want a premium finish and are willing to pay for predictability.

MaxHaus Construction

MaxHaus specializes in modular and prefab ADUs tailored for New York's tight urban lots. Their pre-engineered units can be customized within a range of configurations and are manufactured in their facility before being transported and assembled on-site. For homeowners in Queens or Staten Island with sufficient backyard space, MaxHaus offers one of the fastest paths from contract to occupancy — typically 5–7 months total.

Pricing starts around $200,000 for a 400-square-foot studio and scales up based on size and customization. They handle all structural engineering, which is particularly important in New York where soil conditions and foundation requirements vary significantly by borough.

Brooklyn ADU Partners

A newer entrant focused exclusively on ADU construction in Brooklyn and surrounding areas. They've completed roughly 40 projects since 2024 and have developed standardized floor plans specifically designed for Brooklyn's typical lot sizes (20×100 and 25×100 configurations). Their standardization keeps costs lower than fully custom builds — most projects come in between $190,000 and $320,000.

Understanding ADU utility connections is especially important in New York, where sewer and water tie-ins can add $15,000–$30,000 to your project depending on the borough.

AFFILIATE_CTA: Planning an ADU in New York? Connect with pre-vetted NYC contractors who understand Local Law 156 requirements and DOB permitting.

Best ADU Builders in Chicago (2026)

Chicago's ADU market is the newest of the three, but it's catching up fast. The city's 2020 pilot program and subsequent citywide expansion have created a small but growing pool of experienced builders. Here's who's leading the charge.

Airoom Architects & Builders

Airoom is one of Chicago's largest design-build firms, and they've aggressively moved into the ADU space since the city's program launched. Their integrated architecture and construction model means you get a single point of contact from concept through completion. They're particularly strong for coach house conversions — Chicago's term for the detached structures that sit behind many of the city's older homes.

Airoom's ADU projects typically range from $150,000 to $280,000, significantly less than comparable units in LA or New York. Their design team creates custom plans that work within Chicago's specific zoning requirements, including the lot coverage and setback rules that trip up out-of-market builders.

Chicago Bungalow Association Partners

The Chicago Bungalow Association has partnered with several vetted contractors to offer ADU construction services specifically for owners of Chicago's 80,000+ bungalow-style homes. These partnerships streamline the process for bungalow owners who want to add a backyard ADU or convert an existing coach house.

The association's partner contractors offer standardized pricing and floor plans designed for Chicago's typical bungalow lot (30×125 feet). Most projects through this program cost between $130,000 and $220,000, making them among the most affordable ADU options in any major city. The program also connects homeowners with financing options through local credit unions.

Greenline Construction Group

Greenline focuses on sustainable, energy-efficient ADU construction. Every unit they build meets or exceeds Chicago's energy code requirements and typically includes high-efficiency HVAC, enhanced insulation, and optional solar panel integration. For homeowners planning to rent out their ADU as a short-term rental, the lower utility costs Greenline delivers can significantly improve your rental margins.

Their pricing runs $180–$280 per square foot, which is on the higher end for Chicago but reflects the premium materials and energy systems included. Most projects complete in 6–9 months — faster than either coast.

Urban Dwelling Solutions

A smaller firm that has carved out a niche in affordable ADU construction across Chicago's South and West Side neighborhoods. They work closely with the city's ADU program and have experience navigating the specific requirements for projects in the pilot wards. Their focus on affordability makes them a strong option for homeowners with tighter budgets — basic units start around $110,000 for a 400-square-foot studio.

How to Choose the Right ADU Builder: A Decision Framework

Picking a builder isn't just about price. It's about fit — your budget, your timeline, your tolerance for involvement, and your specific property conditions. Here's a framework that works regardless of which city you're in.

Licensing and Insurance

This is non-negotiable. Every ADU builder you consider should hold a current general contractor license in your state. In California, that's a Class B license from the CSLB (Contractors State License Board). In New York, builders need a Home Improvement Contractor license. In Illinois, it varies by municipality but Chicago requires a General Contractor license through the Department of Buildings.

Beyond licensing, verify that they carry:

General liability insurance (minimum $1 million per occurrence)
Workers' compensation insurance for all employees
Builder's risk insurance covering the structure during construction
Professional liability insurance if they're also providing design services

Ask for certificates of insurance. Call the insurance carrier to verify the policy is current. This takes 15 minutes and can save you from catastrophic liability.

Track Record and References

Ask for references from completed ADU projects — not general remodeling, not commercial work, specifically ADUs. The permitting, design constraints, and construction techniques for ADUs differ enough from standard residential work that general construction experience isn't sufficient.

Request at least three references and actually call them. Ask about:

Was the project completed on time and on budget?
How did the builder handle unexpected issues?
Would you hire them again?
What was the permit timeline?

Contract Structure

The two main contract types for ADU construction are fixed-price and cost-plus. Fixed-price gives you budget certainty but builders pad their estimates to account for unknowns. Cost-plus (where you pay actual costs plus a percentage markup) can be cheaper if the project goes smoothly, but exposes you to overruns.

For most homeowners, a guaranteed maximum price (GMP) contract offers the best balance. The builder commits to a ceiling price, and any savings below that amount are split between you and the builder. This aligns incentives.

Timeline Commitments

Get specific timeline commitments in writing, broken into phases:

Design and engineering: 4–8 weeks
Permitting: 6–16 weeks (highly variable by city)
Construction: 12–32 weeks depending on build type
Inspections and close-out: 2–4 weeks

Include liquidated damages in your contract — a daily penalty if the builder exceeds the agreed timeline without valid cause. This is standard in commercial construction and perfectly reasonable for ADU projects.

Our complete ADU guide covers the full process from planning through move-in.

ADU Costs by City: What to Actually Budget in 2026

Cost is where the three cities diverge most dramatically. Here's what real projects are costing in 2026, based on permit data and builder quotes.

Los Angeles

LA's ADU costs have stabilized after years of increases. The average all-in cost for a detached ADU in Los Angeles County sits at approximately $225,000–$325,000 for a 500–800 square foot unit. That includes design, permitting, site work, construction, and basic landscaping.

Key cost factors specific to LA:

Hillside lots add $30,000–$80,000 for retaining walls, special foundations, and engineering
Seismic requirements are baked into standard construction costs but can increase for older properties requiring foundation upgrades
Solar panel mandates under California's Title 24 energy code add $8,000–$15,000
Garage conversions run 30–40% less than new detached construction, typically $120,000–$200,000

The average cost per square foot in LA is $300–$450, depending on finishes. Budget-conscious homeowners who stick with standard finishes and straightforward lot conditions can hit the lower end. Custom kitchens, high-end bathrooms, and complex sites push toward the top.

New York

New York is the most expensive ADU market of the three. Basement conversions average $150,000–$280,000, depending on the scope of work required to meet Local Law 156 standards. Many basements need waterproofing, structural reinforcement, and complete utility separation — none of which comes cheap with NYC labor rates.

Detached ADUs in the outer boroughs run $280,000–$450,000+ for a comparable unit. Contributing factors include:

Union labor requirements in certain areas increase costs 15–25%
Utility connections are more expensive due to aging infrastructure and Con Edison/National Grid requirements
Soil conditions in parts of Queens and Staten Island require engineered foundations
DOB expediting fees add $5,000–$15,000 for professional permit management

Cost per square foot in NYC ranges from $350–$550, making it roughly 20–30% more expensive than Los Angeles.

Chicago

Chicago is the value play. ADU construction costs average $150,000–$250,000 for a 500–750 square foot detached unit or coach house conversion. The city's lower labor costs, more affordable materials, and less complex permitting process all contribute to the savings.

Cost factors specific to Chicago:

Coach house conversions can be particularly economical if the existing structure is sound — $80,000–$180,000 depending on condition
Weather-related construction limitations (Chicago's winters) can extend timelines and add costs if construction spans November through March
Alley access (common in Chicago) simplifies material delivery and equipment access, reducing site costs
Energy efficiency requirements add $10,000–$20,000 for insulation, windows, and HVAC upgrades suited to Chicago's climate

Cost per square foot in Chicago ranges from $200–$350, making it the most affordable of the three metros.

For a state-by-state breakdown beyond these three cities, see our ADU cost guide.

AFFILIATE_CTA: Get accurate ADU cost estimates for your specific property. Request free, no-obligation quotes from licensed builders in your area.

Permitting and Regulations: What Each City Requires

Permitting is where ADU projects go to die. Or at least to stall for months. Here's what you're facing in each city.

Los Angeles Permitting

California has done more than any other state to streamline ADU permitting. State law now requires cities to approve or deny ADU applications within 60 days of a complete submission. In practice, LA's processing times have improved significantly — many straightforward applications are approved within 30–45 days.

Key LA requirements:

Maximum size: 1,200 square feet for detached ADUs on single-family lots
Setbacks: 4 feet from side and rear property lines for new detached construction
Parking: No additional parking required (a major change from pre-2020 rules)
Owner occupancy: Not required for either the primary dwelling or the ADU
Impact fees: Waived for ADUs under 750 square feet
Design review: No discretionary review — ADUs are approved ministerially if they meet code

California's AB 2221 (effective 2025) further simplified the process by clarifying that cities cannot impose subjective design standards on ADUs. If your plans meet objective zoning and building code requirements, the city must approve them. Period.

New York Permitting

New York's ADU permitting process under Local Law 156 is more complex and still being refined. The key requirements:

Eligible areas: Currently limited to residential zones (R1–R5) in all five boroughs
Basement ADUs: Must have minimum 7-foot ceiling heights, two means of egress, and separate utility metering
Detached ADUs: Limited to rear yards with specific lot coverage and floor area ratio calculations
Owner occupancy: Required — the property owner must live in either the primary dwelling or the ADU
Parking: One off-street parking space may be required depending on the zoning district
Permit timeline: DOB is targeting 60-day reviews but actual processing times have averaged 90–120 days in the first year

The biggest challenge in NYC isn't the rules themselves — it's interpreting them. DOB examiners have inconsistently applied the new ADU provisions, leading to delays and resubmissions. Working with a builder who has existing relationships with DOB staff is worth its weight in gold.

Chicago Permitting

Chicago's ADU ordinance is relatively straightforward compared to LA and NYC:

Eligible properties: Lots zoned RS-1, RS-2, RS-3, RT-3.5, or RT-4 (covers most residential areas)
Maximum size: 700 square feet or 60% of the primary dwelling's footprint, whichever is less
Types allowed: Detached (backyard), attached, and conversions of existing structures (coach houses, garages)
Owner occupancy: Required for the primary dwelling
Parking: No additional parking required
Affordability requirement: In the pilot program, at least one unit (ADU or primary) must be rented at or below 60% of area median income. The citywide expansion has modified this requirement — check current rules.
Permit timeline: Typically 45–75 days through the Department of Buildings

Chicago's process benefits from being newer — the rules were written with modern ADU best practices in mind, avoiding many of the legacy complications that plague older regulatory frameworks.

Financing Your ADU: Options That Work in 2026

Building an ADU isn't cheap, and most homeowners don't have $200,000+ sitting in a savings account. Here are the financing options worth considering.

Home Equity Line of Credit (HELOC)

The most common ADU financing method. If you have significant equity in your home, a HELOC lets you borrow against it at relatively low interest rates. As of early 2026, HELOC rates average 7.5–9.5% depending on your credit profile and lender. The advantage is flexibility — you draw funds as needed during construction rather than taking a lump sum.

Construction Loans

Purpose-built for building projects, construction loans release funds in stages as construction milestones are hit. Rates run slightly higher than HELOCs — 8–10% in the current environment — but they convert to a standard mortgage after construction completes. This is often the best option for homeowners who plan to keep the ADU as a long-term rental.

Cash-Out Refinance

If interest rates have dropped since you locked in your primary mortgage (unlikely for those who bought in 2020–2021 at sub-3% rates, but relevant for more recent buyers), a cash-out refinance lets you tap equity while potentially improving your rate. Given current rate levels, this option only makes sense if your existing mortgage rate is above 7%.

ADU-Specific Lending Programs

Several California-specific programs deserve mention:

CalHFA ADU Grant Program: Provides up to $40,000 for pre-development costs (design, permits, soil testing) as a junior lien that's forgiven if affordability requirements are met
LA County ADU Accelerator: Offers pre-approved ADU plans and expedited permitting to reduce soft costs

New York and Chicago don't yet have comparable state or city-level ADU financing programs, though several are under legislative consideration as of 2026.

Return on Investment

The financial case for ADUs is strong across all three cities. In Los Angeles, a well-located ADU generates $1,800–$3,200/month in rental income depending on neighborhood and unit size. New York ADUs command $2,000–$3,500/month. Chicago rents are lower but so are construction costs — expect $1,200–$2,200/month for a well-finished unit.

At these rental rates, most ADUs achieve a full payback period of 8–15 years, after which they generate pure cash flow. And that doesn't account for the property value increase — studies consistently show ADUs boost property values by 20–35% of the ADU's construction cost.

If you're planning to maximize rental income, our guide on using your ADU as a short-term rental covers the Airbnb angle in detail.

AFFILIATE_CTA: Compare ADU financing options from top lenders. Check your rates in minutes without affecting your credit score.

How We Ranked

ADU-builder rankings combine:

Verifiable program attributes: state contractor license status, recorded build counts, prefab vs site-built specialization, factory-direct vs distributor model, and starting price tier (turnkey ADU under $200K vs $200K-400K vs $400K+).
Owner-reported outcomes: Google reviews from the past 24 months, r/ADU and r/RealEstate threads, BBB complaints, and state contractor-board records. We pay close attention to change-order pricing patterns and timeline overruns.
Direct verification: phone-call or website intake asking the same five questions (turnkey cost, permit-timeline expectation, financing partner, change-order pricing structure, warranty terms).

What we never accept: paid placement, kickback arrangements with builders, financing-partner kickbacks. Disclosure: we use affiliate links to ADU-planning tools (Cover, Multitaskr) — these never affect builder rankings.

Update cadence: builders re-verified each quarter. Email research@adubuildersfinder.com for corrections.

Frequently Asked Questions

How long does it take to build an ADU in Los Angeles, New York, or Chicago?

Timelines vary significantly by city. In Los Angeles, expect 8–14 months from design through move-in for a detached ADU, with permitting accounting for 1–3 months of that total. New York projects run longer — 12–18 months is typical due to DOB processing times and more complex construction logistics. Chicago falls in between at 8–12 months, benefiting from faster permitting but potentially impacted by weather-related construction delays during winter months.

Do I need to live on the property to build an ADU?

It depends on the city. Los Angeles does not require owner occupancy for either the primary dwelling or the ADU — you can build one on a rental property you own. New York requires the property owner to live in either the main house or the ADU. Chicago also requires owner occupancy of the primary dwelling. These rules can change, so verify current requirements with your city's planning department before starting the process.

Can I use my ADU as an Airbnb or short-term rental?

In Los Angeles, short-term rentals (stays under 30 days) are regulated under the Home Sharing Ordinance. You must register with the city and can only list a unit on short-term rental platforms if it's your primary residence — which effectively limits Airbnb use for ADUs unless you live in the ADU and rent out your main house. New York has similar restrictions under Local Law 18. Chicago allows short-term rentals with registration but has specific rules about units in residential buildings. Long-term rentals (30+ days) face fewer restrictions in all three cities.

What's the cheapest type of ADU to build?

Garage conversions and interior conversions (like finishing a basement in New York) are consistently the most affordable ADU types because they use an existing structure. In LA, garage conversions typically cost $120,000–$200,000. In NYC, basement conversions run $150,000–$280,000. In Chicago, coach house conversions start as low as $80,000 if the existing structure is in good condition. New detached construction is always more expensive due to foundation, framing, and utility connection costs.

How do I verify that an ADU builder is legitimate?

Start with license verification through your state's contractor licensing board: CSLB in California (cslb.ca.gov), the NYC Department of Consumer and Worker Protection for New York, and the Illinois Department of Financial and Professional Regulation for Chicago. Cross-reference with the Better Business Bureau, check Yelp and Google reviews for ADU-specific feedback, and ask the builder for at least three references from completed ADU projects. Finally, verify their insurance is current by requesting certificates and calling the insurance carrier directly.