Phoenix ADU + Casita Construction

Arizona's HB 2720 quietly rewrote Phoenix ADU rules on January 1, 2025 — turning what used to be a 12-month zoning fight into a by-right permit. If you own a single-family lot inside Phoenix city limits, you can now build a casita without begging a design-review board, proving you live on-site, or watching your HOA sandbag you for a year. Here's what actually changed, what didn't, and what Baily checks before matching you with a contractor who won't waste your monsoon season.

What Arizona HB 2720 actually unlocked

Before January 1, 2025, building an ADU in Phoenix meant running a gauntlet. You needed to prove owner-occupancy (you had to live in either the main house or the ADU), fight through design-review discretion that could reject your plans on aesthetic grounds, and navigate minimum-lot-size thresholds that quietly disqualified most infill parcels. A typical Arcadia or Encanto ADU pre-2025 took 9–14 months from concept to permit.

HB 2720 forces every Arizona city over 75,000 people — Phoenix obviously qualifies — to permit at least one ADU per single-family residential lot by-right. That phrase is load-bearing. By-right means the city cannot deny your application on discretionary grounds if you meet the objective standards.¹

Phoenix's Ordinance G-7262, adopted December 2024, is the city's HB 2720 implementation. Here's the post-2025 framework:²

What Phoenix can still require:

• 5-foot side and rear setbacks (HB 2720 caps setbacks at what the underlying SFR zone already requires — Phoenix kept its existing 5-ft minimums)
• A 60-day plan-review clock (more on this below)
• HP overlay district design guidelines (historic neighborhoods like Willo, F.Q. Story, Coronado, Roosevelt retain design-review discretion — this is a real carve-out, not a loophole)
• Objective height and size caps: max 1 story above principal dwelling OR 20 feet (whichever is less), max 1,000 sq ft OR 75% of principal dwelling floor area (whichever is less)

What Phoenix can no longer block:

• Owner-occupancy requirements (gone — you can rent both units, long-term)
• Minimum-lot-size increases above the current SFR zone baseline
• Design-review discretion outside HP overlays (your stucco color is your business)
• Parking minimums beyond what the underlying zone requires for the principal dwelling

One genuine gotcha: if your lot sits inside a pre-2015 PUD (Planned Unit Development) with recorded guest-house provisions, those PUD rules grandfather. Arcadia Proper has a handful. Baily checks the PUD overlay on every match before you quote a contractor.

The 60-day PDD plan-review clock

Phoenix's Planning & Development Department runs two lanes through the SHAPE PHX portal: Self-Certification Program and standard plan review.³

Self-certification is the fast lane. If your ADU is under 1,000 sq ft, single-story, and designed by an Arizona-licensed architect or engineer who signs off on code compliance, you skip full plan review. Turnaround is typically 2–4 weeks from complete submittal. The architect/engineer accepts liability for the certification — which is why most homeowners route this through their GC's design partner rather than freelancing it.

Standard plan review is the default path: 6–10 weeks under the 60-day statutory clock Phoenix adopted in G-7262. The clock pauses when PDD kicks back a correction letter (which happens on ~40% of first submittals, usually for energy-code Manual J sizing or stucco wall-assembly specs).

SHAPE PHX walkthrough: create an account at shapephx.phoenix.gov, pick "Residential ADU," upload site plan + floor plan + elevations + structural + MEP, pay the plan-check fee (roughly $800–$1,400 for a typical casita), and you're in queue. The portal shows your status in real time — no more calling PDD and sitting on hold.

ROC license classes that matter for your ADU

Arizona's Registrar of Contractors (ROC) is the CSLB-equivalent. For a Phoenix ADU, the license class that matters is B-3 General Residential Contractor — the dominant whole-home + ADU class. A B-3 holder can self-perform or sub framing, MEP, stucco, roofing, and finishes on residential structures up to and including your ADU.⁴

If your ADU touches a pool deck, pool equipment pad, or pool plumbing (common for backyard casitas in Paradise Valley and Scottsdale-adjacent Phoenix lots), the contractor — or their sub — needs CR-6 Swimming Pools on top of the B-3. A B-3 alone cannot legally pull a pool-adjacent permit.

What Baily verifies per match, before you ever talk to the contractor:

1. Active ROC license (lookup at roc.az.gov — takes 15 seconds, nobody does it)
2. $15,000+ bond posted (minimum for B-3; some carry $30K–$50K on larger books)
3. Residential Recovery Fund eligibility — Arizona's homeowner-protection fund pays up to $30K per claim if the contractor defaults. Only ROC-licensed residential work qualifies. Unlicensed builds are not covered, full stop.
4. No open disciplinary actions in the ROC complaint database

The "handyman my cousin recommended" path bypasses all four. That's not Baily's lane.

Cost ranges — what a Phoenix ADU actually runs

Phoenix ADU pricing in 2025, real numbers from closed projects:

• New-build detached ADU (600–900 sq ft): $180,000–$350,000 all-in (design + permit + construction). The spread depends on finish level, foundation type (post-tension slab vs conventional), and whether you're running new utilities or extending from the main house.
• Detached garage conversion: $120,000–$220,000. Cheapest legal path. Existing slab, existing walls, existing roof — you're primarily adding MEP, insulation, a kitchen, a bathroom, and meeting egress.
• Attached ADU / junior ADU (bump-out off main house): $160,000–$280,000. Shares utility runs with the principal dwelling; cheaper MEP, trickier structural.

Why monsoon timing matters. Phoenix's monsoon season runs June 15 – September 30. PDD inspection backlogs swell 2–3x during monsoon because framing and stucco inspections stall out on rain days (and dust-storm days — haboobs are real). A project that breaks ground in March will finish drywall before monsoon hits. A project that breaks ground in May will sit open-frame in August watching water pond in the footings. Good GCs price this in. Bad ones don't.

HOA design-review comfort zone. Even though HB 2720 killed city-level design review outside HP overlays, your HOA retains exterior-materials authority (more below). That means your $300K ADU can still be forced to match the principal dwelling's stucco color and roof tile — which is fine, but only if your GC specs it from day one rather than change-ordering in month four.

HOA-check: the hidden gate

Roughly 60% of Phoenix metro single-family homes sit inside an HOA. HB 2720 did not override HOAs — it overrode the city. Two Arizona statutes govern what your HOA can and cannot do to your ADU:⁵

ARS §33-1817 lets HOAs regulate exterior paint colors, roofing materials, landscape, and driveway surfacing. This is broad. An HOA can require you to match existing stucco color within a Sherwin-Williams chip range, require tile roofing over shingle, require desert-adapted xeriscape, and require decomposed granite vs. concrete for the ADU's walkway.

ARS §33-1816 protects solar. Your HOA cannot block rooftop PV on the ADU, though they can regulate mounting aesthetics within "reasonable" bounds.

What your HOA cannot do post-HB 2720: deny the ADU itself, impose owner-occupancy covenants that conflict with state law, or require minimum lot sizes above the city baseline.

AskBaily surfaces the HOA architectural-review gate before any city permit pulls. That order matters. Homeowners who skip this step routinely eat 3–8 week delays when the HOA ARC kicks back stucco specs after PDD has already approved plans. Order of operations: HOA ARC approval → final construction docs → SHAPE PHX submittal → permit → build.

Garage conversion — the most common ADU path

If you have a detached garage (or an attached garage you're willing to give up), this is the cleanest HB 2720 path in Phoenix. You're not adding building footprint, you're not fighting stormwater calcs, and your existing foundation is already permitted.

Conversion requirements that trip up first-time owners:

• Plumbing stubbing: the existing slab must be cut for DWV (drain-waste-vent) and supply. If the original slab was poured without a vapor barrier (common in pre-1980 Phoenix garages), you may need slab remediation before finish floor.
• Electrical: ADU needs its own subpanel sized for kitchen + HVAC + laundry — typically 100A feeder from the main service. Many older Phoenix garages run a 60A sub that won't pass.
• Mini-split vs central: Mini-splits (ductless) are the default for Phoenix garage conversions — no ductwork retrofit, higher SEER, zoned cooling. A single 18,000-BTU head covers ~600 sq ft at Phoenix design-day loads. Central-air extensions from the main house rarely pencil.
• Egress window: any room used for sleeping needs a code-compliant egress window (5.7 sq ft clear opening, max 44-in sill height). Garage door openings don't count.
• Stucco repair: Phoenix's IRC amendment R703.6 requires three-coat hard-coat stucco over a two-layer Grade D weather-resistive barrier — not single-layer Tyvek. If your GC proposes one-coat synthetic or single-ply WRB, that's a correction letter waiting to happen.⁶

Why Baily matches 1 GC, not 12

Phoenix has roughly 400 actively-licensed B-3 residential general contractors. Of those, maybe 80 have real ADU portfolios — meaning 5+ closed Phoenix ADU projects in the last 24 months, clean ROC record, and a bond posture that matches project size.

Baily filters for:

• Active ROC B-3 (and CR-6 if pool-adjacent)
• Minimum $15K bond, prefer $30K+
• Zero open ROC complaints in the last 18 months
• Maricopa County Hispanic Chamber of Commerce membership preferred (not required) — local-network depth shows up in subcontractor availability during monsoon crunch
• HB 2720 familiarity confirmed in intake (some GCs still quote pre-2025 timelines)

You get one match. One quote. One contractor who's read your HOA CC&Rs before they walk your lot. Angi sends your phone number to twelve strangers. Baily sends your scope to one vetted GC.

Frequently Asked Questions

Does my Phoenix neighborhood allow an ADU after HB 2720? Yes, if your lot is zoned single-family residential (R1-6, R1-8, R1-10, R1-14, R1-18, R1-35, S-1, RE-24, RE-35). HB 2720 made ADUs by-right citywide effective January 1, 2025, and Phoenix's Ordinance G-7262 implemented it December 2024. Real exceptions: HP overlay districts (Willo, Coronado, F.Q. Story, Roosevelt, and ~10 others) retain design-guideline discretion, which adds 4–8 weeks and can require specific materials. Pre-2015 PUDs with recorded guest-house provisions grandfather under prior rules. Baily checks both overlays on every match.

Can my HOA block my ADU? No on the ADU itself — state law preempts HOA prohibitions after HB 2720. Yes on exterior materials, colors, roofing, landscape, and driveway surfacing per ARS §33-1817. Practical effect: your HOA cannot deny the permit, but they can force your ADU to match the principal dwelling's stucco color, tile roof, and xeriscape standards. Solar panels on the ADU roof are protected by ARS §33-1816. Always clear HOA architectural review before SHAPE PHX submittal.

What's the difference between a casita and an ADU in Phoenix? Practically interchangeable now post-HB 2720. "Casita" is the colloquial Southwestern term, "ADU" (accessory dwelling unit) is the code-defined term Phoenix uses in G-7262. Historically Phoenix used "guest house" for pre-2015 stock, which had stricter owner-occupancy and no-kitchen requirements. Modern ADUs/casitas have full kitchens, full bathrooms, separate utilities (optional), and are legally rentable long-term. Short-term rentals (Airbnb, under 30 days) are separately regulated by Phoenix STR ordinance — check that before planning Airbnb income.

How long does a Phoenix ADU permit take? Self-certification track through SHAPE PHX: 2–4 weeks typical from complete submittal to issued permit, if your plans are signed by an Arizona-licensed architect or engineer accepting code-compliance liability. Full plan review: 6–10 weeks under Phoenix's 60-day statutory clock, with the clock pausing on correction letters. Add 4–8 weeks for HP overlay design review if you're in a historic district. Add 2–4 weeks for HOA ARC review (run in parallel, not serial). Realistic concept-to-permit for a typical Phoenix casita: 3–4 months. Concept-to-move-in: 9–14 months.

What's the cheapest Phoenix ADU path? Converting a detached garage: $120,000–$220,000 vs. $180,000–$350,000 for new build. You're reusing foundation, walls, and roof — spending primarily on MEP, insulation, kitchen, bath, egress, and stucco repair. Key caveat: the existing garage slab must be inspectable for frost-free depth (less of an issue in Phoenix) and moisture barrier. Pre-1980 Phoenix garages often lack a vapor barrier under the slab, which can force slab remediation before finish floor — a $8K–$15K line item that kills the budget advantage if it surfaces mid-build. A pre-construction slab moisture test ($400–$600) is worth every dollar.