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 [15][16][17][18][19][20]
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) | $150,000-$280,000 |
| Cost per Sq Ft | $200-$350 |
| Garage Conversion | $80,000-$150,000 |
| Prefab / Modular ADU (installed) | $155,000-$300,000 |
| City Permit & Plan Review | Valuation-based (PDD Fee Schedule, Ordinance G-7465, effective January 20, 2026, Table A): permit fee $703 on the first $50,000 plus $9 per $1,000 up to $200,000, then $2,053 plus $9 per $1,000; residential plan review is 80% of the permit fee when valuation exceeds $50,000 (100%, minimum $195, at or below); plot plan review $98; each extra utility meter $98. Examples: a $150,000 valuation is about $1,603 permit + $1,282 plan review + $98 = $2,983; $250,000 is about $2,503 + $2,002 + $98 = $4,603. Valuation is the higher of the city's square-foot valuation table or your contract price. Re-inspections after the first are $195 each |
| Impact Fees | Depends on where the lot is. Under the Development Impact Fee schedule effective June 23, 2025, the established city ('Balance of City') pays no fire, police, parks, library, arterial or storm-drain impact fees; the growth-area zones (Northwest, Deer Valley, Northeast, Paradise Ridge, Estrella, Laveen, Ahwatukee) charge a single-family dwelling roughly $12,000-$35,000 in total. Citywide the schedule lists per-dwelling water treatment ($4,387), wastewater treatment ($1,071) and water resource acquisition ($2,009, off-project) fees for a single-family unit on a meter up to 1 in. The schedule does not say whether an ADU on the house's existing meter is assessed, so email impactfees@phoenix.gov with your APN before budgeting; a 1% administrative charge applies to any gross fee |
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: 75% of the primary home's gross floor area (interior habitable area), and no more than 1,000 sq ft on a lot of 10,000 sq ft or less; on a lot over 10,000 sq ft, the lesser of 3,000 sq ft or 10% of net lot area (ZO 706.A.8). A garage, carport or attached shade structure built as part of a detached ADU does not count toward its floor area but does count toward lot coverage; owner-occupancy: Not required. Either the house or the ADU may be rented long-term (90-day or month-to-month leases) with no family or employment relationship (ARS 9-461.18.B.1-2). Only exception: to hold a short-term rental permit on a property whose ADU was finaled on or after September 14, 2024, the owner must attest and prove they live on the property (City Code Ch. 10 Art. XVI, effective April 4, 2026)).
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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 (Valuation-based (PDD Fee Schedule, Ordinance G-7465, effective January 20, 2026, Table A): permit fee $703 on the first $50,000 plus $9 per $1,000 up to $200,000, then $2,053 plus $9 per $1,000; residential plan review is 80% of the permit fee when valuation exceeds $50,000 (100%, minimum $195, at or below); plot plan review $98; each extra utility meter $98. Examples: a $150,000 valuation is about $1,603 permit + $1,282 plan review + $98 = $2,983; $250,000 is about $2,503 + $2,002 + $98 = $4,603. Valuation is the higher of the city's square-foot valuation table or your contract price. Re-inspections after the first are $195 each), plan check (Full residential plan review (no over-the-counter path for ADUs). Submit a plot plan with site-planning approval, floor plans, elevations, structural and energy-code documents per the Residential Plan Submittal Checklist, and note fire-rating requirements per IRC R302; no grading-and-drainage plan is required for an attached or detached ADU (TRT/DOC/00192). Extra reviews apply on hillside lots (slope over 1:10), historic properties and floodplain lots. State law bars the city from requiring a fire sprinkler or commercial-code compliance in an ADU (ARS 9-461.18.D)), and impact fees (Depends on where the lot is. Under the Development Impact Fee schedule effective June 23, 2025, the established city ('Balance of City') pays no fire, police, parks, library, arterial or storm-drain impact fees; the growth-area zones (Northwest, Deer Valley, Northeast, Paradise Ridge, Estrella, Laveen, Ahwatukee) charge a single-family dwelling roughly $12,000-$35,000 in total. Citywide the schedule lists per-dwelling water treatment ($4,387), wastewater treatment ($1,071) and water resource acquisition ($2,009, off-project) fees for a single-family unit on a meter up to 1 in. The schedule does not say whether an ADU on the house's existing meter is assessed, so email impactfees@phoenix.gov with your APN before budgeting; a 1% administrative charge applies to any gross fee) are included.
- Permit handling: Confirm they manage Phoenix's permit process ("By-right building permit; a code-compliant ADU needs no public hearing, variance or use permit (ARS 9-461.18 'permitted use'; ZO 608.E.2, 706.A). Order of work: 1) confirm zoning on My Community Map and lot size and building footprints on the Maricopa County Assessor record; 2) obtain site-planning approval of a scaled plot plan showing setbacks and lot coverage; 3) submit the residential plan set through the SHAPE PHX portal or at the Residential counter, 200 W. Washington St., 2nd floor (ADU submittals are logged in for full review, not over the counter); 4) pay permit fees; 5) inspections (602-495-0800) and final. A Section 307 use permit is needed only to exceed 15 ft inside a required yard or to place a detached ADU in front of the house. Separate address on request from Addressing Services (602-256-3127); one combined water meter service is the standard", typically Not published as a fixed ADU figure. Planning & Development posts a monthly Plan Review Turnaround Times report (goal vs. actual, by plan type) on its Reports, Data and Turnaround Times page; plan on at least one correction cycle. Phoenix builders' 2026 guides quote 6-12 months from design start to move-in for a detached casita and 4-6 months for a garage conversion) 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 (Not published as a fixed ADU figure. Planning & Development posts a monthly Plan Review Turnaround Times report (goal vs. actual, by plan type) on its Reports, Data and Turnaround Times page; plan on at least one correction cycle. Phoenix builders' 2026 guides quote 6-12 months from design start to move-in for a detached casita and 4-6 months for a garage conversion) 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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How much do ADU builders charge in Phoenix?
ADU builders in Phoenix typically quote $150,000-$280,000 for a new detached unit, or about $200-$350 per square foot, including design, permitting, and construction. A garage conversion runs $80,000-$150,000 and a prefab/modular ADU averages $155,000-$300,000. Add city permit and plan-review fees (Valuation-based (PDD Fee Schedule, Ordinance G-7465, effective January 20, 2026, Table A): permit fee $703 on the first $50,000 plus $9 per $1,000 up to $200,000, then $2,053 plus $9 per $1,000; residential plan review is 80% of the permit fee when valuation exceeds $50,000 (100%, minimum $195, at or below); plot plan review $98; each extra utility meter $98. Examples: a $150,000 valuation is about $1,603 permit + $1,282 plan review + $98 = $2,983; $250,000 is about $2,503 + $2,002 + $98 = $4,603. Valuation is the higher of the city's square-foot valuation table or your contract price. Re-inspections after the first are $195 each) plus impact fees of Depends on where the lot is. Under the Development Impact Fee schedule effective June 23, 2025, the established city ('Balance of City') pays no fire, police, parks, library, arterial or storm-drain impact fees; the growth-area zones (Northwest, Deer Valley, Northeast, Paradise Ridge, Estrella, Laveen, Ahwatukee) charge a single-family dwelling roughly $12,000-$35,000 in total. Citywide the schedule lists per-dwelling water treatment ($4,387), wastewater treatment ($1,071) and water resource acquisition ($2,009, off-project) fees for a single-family unit on a meter up to 1 in. The schedule does not say whether an ADU on the house's existing meter is assessed, so email impactfees@phoenix.gov with your APN before budgeting; a 1% administrative charge applies to any gross fee. 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 "By-right building permit; a code-compliant ADU needs no public hearing, variance or use permit (ARS 9-461.18 'permitted use'; ZO 608.E.2, 706.A). Order of work: 1) confirm zoning on My Community Map and lot size and building footprints on the Maricopa County Assessor record; 2) obtain site-planning approval of a scaled plot plan showing setbacks and lot coverage; 3) submit the residential plan set through the SHAPE PHX portal or at the Residential counter, 200 W. Washington St., 2nd floor (ADU submittals are logged in for full review, not over the counter); 4) pay permit fees; 5) inspections (602-495-0800) and final. A Section 307 use permit is needed only to exceed 15 ft inside a required yard or to place a detached ADU in front of the house. Separate address on request from Addressing Services (602-256-3127); one combined water meter service is the standard". Review time: not published as a fixed ADU figure. Planning & Development posts a monthly Plan Review Turnaround Times report (goal vs. actual, by plan type) on its Reports, Data and Turnaround Times page; plan on at least one correction cycle. Phoenix builders' 2026 guides quote 6-12 months from design start to move-in for a detached casita and 4-6 months for a garage conversion. Confirm in writing whether permit fees, plan check (Full residential plan review (no over-the-counter path for ADUs). Submit a plot plan with site-planning approval, floor plans, elevations, structural and energy-code documents per the Residential Plan Submittal Checklist, and note fire-rating requirements per IRC R302; no grading-and-drainage plan is required for an attached or detached ADU (TRT/DOC/00192). Extra reviews apply on hillside lots (slope over 1:10), historic properties and floodplain lots. State law bars the city from requiring a fire sprinkler or commercial-code compliance in an ADU (ARS 9-461.18.D)), 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 (Not published as a fixed ADU figure. Planning & Development posts a monthly Plan Review Turnaround Times report (goal vs. actual, by plan type) on its Reports, Data and Turnaround Times page; plan on at least one correction cycle. Phoenix builders' 2026 guides quote 6-12 months from design start to move-in for a detached casita and 4-6 months for a garage conversion 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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