ADU Builders in Phoenix, AZ (2026)

An ADU builder in Phoenix is a licensed contractor who designs and constructs accessory dwelling units — detached backyard units, garage conversions, attached additions, and junior ADUs (JADUs). Because an ADU is a complete second dwelling, the builder coordinates foundation, framing, plumbing, electrical, and HVAC work and pulls it through Phoenix's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in Arizona.

What ADU Builders Cost in Phoenix ^[5]^[6]

Based on our Phoenix cost data, expect the following ranges from local ADU builders. Quotes for the same scope typically vary 20-40% between contractors, so getting at least three bids is the single best way to control cost.

New Detached ADU (all-in)	$120,000-$240,000
Cost per Sq Ft	$135-$270
Garage Conversion	$60,000-$140,000
Prefab / Modular ADU (installed)	$85,000-$200,000
City Permit & Plan Review	$2,500-$4,200
Impact Fees	$900-$1,600

For a full line-item breakdown, see our Phoenix ADU cost guide. To confirm what you're allowed to build before you hire, review the Phoenix ADU rules (max detached size: 1,000 sq ft on lots up to 10,000 sq ft (75% of primary dwelling, whichever is less); on lots over 10,000 sq ft, the lesser of 3,000 sq ft or 10% of net lot area; owner-occupancy: Not required for long-term rental; owner must reside on-site only if an ADU built on/after Sept 14, 2024 is used as a short-term/vacation rental).

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How to Vet an ADU Builder in Phoenix

License: Confirm a current contractor's license in Arizona and that it's in good standing. Ask for the license number and verify it with the state board.
ADU-specific experience: Ask how many ADUs they've completed in or near Phoenix and request addresses or photos. ADU permitting and setbacks differ from a kitchen remodel.
Portfolio & references: Get references from recent ADU clients and, if possible, visit a finished unit.
Insurance: Verify general liability and workers' compensation coverage. Ask for a certificate of insurance.
Written, detailed bid: Insist on an itemized, fixed-price or clearly-scoped bid — not a verbal estimate. It should state whether permits ($2,500-$4,200), plan check (2-3 weeks), and impact fees ($900-$1,600) are included.
Permit handling: Confirm they manage Phoenix's permit process ("Building permit", typically 60-90 days) and who is responsible if revisions are required.
Payment schedule: Avoid large upfront payments. A reasonable schedule ties payments to completed milestones.

Questions to Ask Before You Hire

How many ADUs have you built in Phoenix in the last two years?
Is your bid fixed-price, and what would trigger a change order?
Are permits, plan check, and utility connection fees included?
What's a realistic timeline, including permit review (60-90 days) and construction?
Who is my point of contact and how are delays communicated?
What warranty do you provide on workmanship?
Can you share three recent Arizona ADU client references?

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Frequently Asked Questions

How much do ADU builders charge in Phoenix?

ADU builders in Phoenix typically quote $120,000-$240,000 for a new detached unit, or about $135-$270 per square foot, including design, permitting, and construction. A garage conversion runs $60,000-$140,000 and a prefab/modular ADU averages $85,000-$200,000. Add city permit and plan-review fees of $2,500-$4,200 plus impact fees of $900-$1,600. Quotes for the same scope commonly vary 20-40% between builders, so collect at least three bids.

How do I find a good ADU builder in Phoenix?

Look for a licensed contractor with completed ADU projects in Phoenix specifically — ADUs involve local zoning, setback rules, and utility connections that general remodelers may not have handled. Verify the license, ask for an ADU-specific portfolio and references, confirm they carry liability and workers' comp insurance, and get a written fixed-price or detailed bid. Submit a request below and we'll forward it to local ADU builders serving Phoenix for free quotes.

Do ADU builders in Phoenix handle permits?

Most full-service ADU builders manage the permit process for you. In Phoenix the approval process is "Building permit" with a typical review timeline of 60-90 days. Confirm in writing whether permit fees, plan check (2-3 weeks), and impact fees are included in the bid or billed separately.

How long does it take to build an ADU in Phoenix?

Plan for the permit review (60-90 days in Phoenix) plus construction. Most detached ADUs take 4-8 months of construction after permits are issued; garage conversions and prefab units are often faster. Ask each builder for a realistic schedule and what could delay it.

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Build Cost	$120,000-$240,000
Garage Conv.	$60,000-$140,000
Permit Fees	$2,500-$4,200
Timeline	60-90 days
1BR Rent	$1,250-$1,700/mo

What ADU Builders Cost in Phoenix [5][6]