So we pulled numbers from the ADU work we've done in Phoenix, ran the math on projects we've built, and wrote this page. Real Phoenix ADU cost ranges. The six things that actually move the cost. The honest math we'd walk you through if you sat down with us.
No "starting at" numbers. No fine print. Just the answers we wish more ADU contractors would put in writing.
Most homeowners who find this page have been thinking about an ADU or casita for a while. Not casually. The kind of thinking where you've walked the back of the property more than once, sketched something out, run the numbers on what your aging parent's care could cost versus what their own space on your lot could cost instead, or wondered what your guest house could rent for the eight months a year it would otherwise sit empty.
You are not just curious. You are here because the math is starting to make sense.
You have probably seen numbers by now. Maybe from a neighbor who built something a few years back, maybe from a contractor who threw out a per-square-foot number that had very little to do with your lot, your existing house, or what you actually want to build. Maybe from a turnkey ADU company whose price sounded great until you read the fine print on what wasn't included. None of those numbers felt quite right, and none of them came with an explanation.
This page is the explanation.
We built it because the question of what an ADU costs in Phoenix deserves a real answer. Not a range so wide it tells you nothing. Not a per-square-foot number borrowed from new construction pricing that ignores the foundation, the utility runs, the permit reality, and the fact that ADU costs in Phoenix vary considerably by city ordinance, by lot, and by whether you are building detached, attached, or converting an existing structure. What you will find here is real data, plain language, and enough context to make a decision that fits your property and your plans.
Scroll through at your own pace. The estimator is waiting at the bottom when you are ready.
You've been thinking about an ADU for a while. Maybe you got a quote a few years back and filed it away. Now you're back, and the number feels different.
If it feels more expensive than it used to...
Guest house or casita conversion
$80k–$150k
national average
Detached guest house or new ADU
$150k–$300k
national average
Conversion or attached ADU
$150k–$275k
Phoenix area
Detached new build ADU
$300k–$600k+
Phoenix area
+75 to 100%
ADU costs in Phoenix have risen significantly since 2019.
Understanding why that happened and what you can do about it is exactly what this page is for.
2019 figures: Remodeling Magazine Cost vs. Value Report and NAHB Cost of Constructing a Home Survey (addition and new-construction data used as the closest national proxies for pre-HB 2720 ADU costs, scaled to the typical ADU footprint). Current figures: Phoenix metro area, based on NAHB Cost of Constructing a Home Survey (2025), Verisk Q1 2025 Repair and Remodel Index, Harvard Joint Center for Housing Studies, and Hochuli ADU and addition-with-kitchenette project data. 2024 passage of Arizona HB 2720 raised the regulatory and code floor for ADU construction across the state, which contributes to the gap between 2019 and current figures. All figures reflect full ADU scope including foundation (where applicable), utility extensions, kitchen, bathroom, and finishes. Scope, lot conditions, city ordinance, and finish level significantly affect final cost. Last updated December 2026. This page is reviewed and updated annually.
A lot has changed in the last six years, and not all of it in the direction you're hoping for. Before we get into specifics, take a look at what the data actually shows.
Phoenix home value increase
+75%
2019 to 2025
ADU construction cost increase
+60%
2019 to 2025, Phoenix area
Did pandemic prices come back down?
They didn't.
this is the new floor
Home value data: S&P Case-Shiller Phoenix Home Price Index / Zillow Phoenix Metro. ADU construction cost data: NAHB Cost of Constructing a Home Survey (2019–2025 editions), Verisk Q1 2025 Repair and Remodel Index, Harvard Joint Center for Housing Studies, Hochuli ADU and addition-with-kitchenette project data. ADU-specific construction cost line indexed using new-construction and addition cost data scaled to typical ADU footprint and scope; 2024 passage of HB 2720 raised the regulatory floor for ADU construction, contributing to the gap between 2019 baselines and current figures. Phoenix-area construction costs typically run 5–12% above national benchmarks. All figures indexed to 2019 = 0% baseline.
Let's talk about something most ADU contractors won't.
Prices went up. A lot. Between pandemic demand, material shortages, labor gaps, the 2025 tariffs on imported building materials, and the 2024 HB 2720 code-floor reset, what an ADU costs to build today looks very different from what a guest house cost in 2019. We're talking roughly 60% higher in the Phoenix area, with the gap widening further for ADUs that meet the full HB 2720 spec versus pre-2024 guest house construction.
That number deserves some context, though.
Your home's value also went up. A lot. Phoenix homeowners have seen roughly 75% appreciation since 2019. So the lot you're considering adding an ADU to has grown considerably in value, which means the project you've been weighing is going up against an asset worth significantly more than it was when you first started thinking about it.
We're not going to tell you the timing is perfect. We're going to tell you the numbers are real, and you deserve to see them before making a decision this big.
Data last updated: December 2026. This page is reviewed and updated annually.
None of them are going away anytime soon.
There aren't enough skilled tradespeople in Phoenix to meet demand, and we've seen this firsthand on every project we've built since 2021. An ADU touches every trade in the building, and skilled labor in all of those categories has gone up roughly 20% since 2019. Wages went up because they had to, and they're staying up. This is the biggest single piece of the cost increase, and it isn't a Phoenix problem; it's a national one.
Lumber, copper, steel, drywall, concrete. Most everything that touches an ADU jumped during the pandemic and never came back to where it was. ADUs are particularly exposed because you're often building structure from scratch: foundation, framing, sheathing, roofing. That's where the material cost increases hit hardest. When materials cost more, your ADU costs more, end of story.
The 2025 tariffs on Canadian lumber, imported cabinetry, and finish materials have been baked into manufacturer pricing. For ADUs specifically, this hurts twice: once on the structural framing package, and again on the cabinets, fixtures, and trim that go into a unit small enough that every finish choice is visible. Sub-Zero, Wolf, and most appliance lines have all repriced significantly since 2020 as well.
This is the cost most ADU prospects don't see coming. A detached ADU on a Phoenix lot almost always needs the sewer line extended from the main house, a new electric service run from the panel or a separate meter set, sometimes a separate gas meter, and water tap or capacity fees from the city. On the right lot, this is $15k. On a difficult lot or a project that needs full utility separation for rental compliance, it can run $50k or more. Conversion paths (garage or existing structure) carry far less utility burden, which is part of why they're cheaper.
Arizona's 2024 HB 2720 set a statewide floor for ADU approval, but every Phoenix-area city still has its own ordinance layered on top. Setbacks, lot coverage, owner-occupancy, parking requirements, short-term rental rules. Paradise Valley is exempt from HB 2720 entirely. Scottsdale and Phoenix have different approaches to detached versus attached. The compliance work (survey, engineering revisions, plan reviews, sometimes multiple rounds with the city) has real cost. We cover the city-by-city detail in our Phoenix ADU rules guide.
Phoenix has added hundreds of thousands of residents over the past six years. The pool of qualified contractors who can actually pull ADU permits, manage a small structural project from foundation to finish, and integrate the work cleanly into a livable lot hasn't kept pace. We don't take more work than we can complete well, which means our schedule fills up earlier in the year than it used to. The question worth asking is what you're paying for, not just what you're paying.
Nobody walks into an ADU project hoping to spend more than they have to. And while a lot of what drives costs up is completely out of your hands, some of it is not. Here are the levers we work through with every ADU client.
The single biggest cost saver on an ADU project. A 300 square foot garage conversion with a kitchenette and a 3/4 bath can land around $165k. A detached new-build ADU at the same scope and finish level will run nearly double. The foundation, the envelope, the roof are already there in a conversion. You are paying for interior reconfiguration, utility upgrades, kitchenette and bath, and finishes. If your property has a structure that could be converted (garage, workshop, pool house), that path is almost always the cheaper way to a finished ADU.
A kitchenette (sink, small refrigerator, microwave, two-burner cooktop, limited cabinetry) versus a full kitchen (range, oven, dishwasher, full cabinet run, larger refrigerator) is a difference of $25k or more at any finish level. If the ADU is for a guest, a short-term rental, or an aging parent who eats most meals in the main house, a kitchenette is usually plenty. Full kitchens earn their place when the ADU is a true second household, a long-term rental marketed as a one-bedroom, or family use that requires full cooking independence. Most prospects assume they need a full kitchen and find out later they didn't.
If your property allows it, an attached ADU is meaningfully less expensive than a detached new build. Attached means lower foundation cost, shorter utility runs, often a shared roof line, and easier permitting in some cities. A 450 square foot attached ADU with a kitchenette and full bath can land around $225k. The detached equivalent will be closer to $325k. Detached has its own value (privacy, true separation, easier rental positioning), but if cost is the driver and your lot can accommodate it, attached is the lever to pull.
A common mistake we see prospects make is wanting the ADU to be a showpiece when the use case calls for something more practical. A long-term rental needs durable finishes, easy-clean surfaces, and mechanicals chosen for low maintenance. A family member's space wants comfort and warmth, not designer everything. A short-term rental benefits from one or two visual moments (a great tile shower, a feature wall) and otherwise practical choices. Designer-grade finishes in every category add $40k to $80k to the project and often do not match the way the space will actually get used. Spending where it matters and saving where it does not is one of the most important conversations we have in design.
If you are weighing an ADU alongside other remodel work on the main house, phasing can save real money. Build the ADU first and use it as a construction-period rental or family lodging while you do the main house remodel later. Or do the main house first and use the equity gain to fund the ADU. The trade off is you are disrupted twice instead of once, but for plenty of clients the cash flow benefit and the sequencing flexibility outweigh the disruption.
Most prospects come in asking about a larger ADU than they need. They anchor on what the lot can accommodate rather than what the use case calls for, and the difference between "comfortable for the use case" and "as big as we can fit" is often 200 to 400 square feet of space that costs real money to build and finish but doesn't add usable function. A right-sized smaller ADU built well is a better project than a larger one stretched thin on finishes to hit a target cost. Walk through the actual use case during design (who lives or stays there, how often, what they need to function) and the square footage almost always lands lower than the starting wish list. That conversation is one of the most valuable things our design phase does for prospects who are willing to have it.
Content last updated: December 2026. This page is reviewed and updated annually.
Every ADU is different. These three profiles give you a realistic starting point based on path, size, finish level, and use case. Most ADU projects we build or would build fall somewhere within these ranges.
The Essential ADU is the right project for prospects who have an existing structure to convert or the lot for a modest attached unit. Garage conversion with a kitchenette and three-quarter bath. Small attached addition built to function as a guest suite, casita, or compact one-bed rental. Semi-custom cabinetry, durable surfaces, mid-grade fixtures, and the same attention to detail we bring to every project we build. The homeowner who chooses this path has a clear use case (aging parent, adult child, guest space, modest rental), is not interested in building larger than they need, and wants the unit to feel like a finished, livable space the day it is done.
View Project Gallery →
The Premium ADU is the most common ADU project we see prospects seriously planning. Mid-size attached unit with full kitchen and full bath, or smaller detached new build with full systems and finishes matched to the main house. Custom or semi-custom cabinetry, designer tile, expanded shower, upgraded fixtures, and a finish level that positions the ADU as a true second residence rather than an entry-level guest space. This is the tier most long-term family use, serious rental positioning, and primary-residence-quality projects land in. The homeowner who chooses this path has thought carefully about the use case and is investing in something that will serve that use case for decades.
View Project Gallery →
The All-In ADU is a freestanding, fully appointed second residence. Detached new build, larger footprint, full custom cabinetry, premium natural stone, designer everything, often with smart-home wiring and architectural details that tie the ADU into the main house and the property as a cohesive whole. The kind of ADU that earns top-of-market rental rates, hosts visiting family in comfort that rivals the main house, or functions as a true downsizing option for owners who want to stay on the property they love. Often paired with landscape work that integrates the unit into the broader lot.
View Project Gallery →
My wife and I purchased a home in Paradise Valley that was perfect for our family but seriously outdated. We wanted to redo the kitchen, all of the bathrooms, the laundry room, and the flooring throughout, and we were overwhelmed by how much work that was. Calling Hochuli was the best thing we ever did. They made the process easy from start to finish and handled everything for us. We will definitely be using the Hochuli's again for our next big project.
This is our second remodel with Lorrie and Scott. We added 900 square feet, redid the kitchen and flooring, changed the floor plan, and they coordinated seamlessly with our pool builder doing the backyard at the same time. It turned out better than we could have imagined.
I was anxious about remodeling my Scottsdale home since I'd never taken on a project that size and had no idea what to expect. That changed once I connected with Scott and his team. They explained the entire process, from planning to what daily life during construction would actually feel like. They completed a full remodel of my 4,000 square foot home, including the kitchen, four bathrooms, plus new flooring and paint throughout. The initial investment ended up being higher than I first anticipated, but I was actively involved in the design decisions, so that was on me. I don't regret it at all and confidently recommend the Hochuli team to friends and family.
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A $250,000 ADU over 20 years.
Per month. For the space that lets your family live the way you want to live.
Here is a thought experiment. Take a Premium ADU. Call it $250,000. Most clients who build an ADU at this level intend to keep it on the property for at least 20 years afterward, often longer. That is not us guessing. That is what they tell us when we ask why they are building one in the first place.
The ADU is going to serve a purpose that touches your life every single day for the next two decades. The aging parent who needs their own space close to family. The adult child who is launching their career but cannot afford a separate home in this market. The guest suite that finally lets people visit comfortably. The rental that offsets a meaningful portion of the mortgage on the main house. The office or studio that gives you somewhere to close the door. Whatever the use, it is one you chose because the alternative was not working.
So let us actually do the math on what this investment costs per month for the next two decades.
$250,000 divided by 20 years divided by 12 months. That math sounds like a trick. It is not. It is just what happens when you spread a one-time investment across the actual life of the ADU.
The math changes further when you consider what a poorly executed ADU actually costs. A unit built on the lowest possible bid that develops roof leaks in five years, foundation problems in eight, or a tie-in that fails in twelve costs you twice. The structural repairs, the disruption, the contractor search all over again, plus the damage to the main house that the failed ADU caused. An ADU built right the first time by people who stand behind their work is not just a better ADU. It is a better investment.
The real question is not whether $250,000 is a lot of money. It is.
The real question is whether you would pay $1,042 a month for the next 20 years to have the space, the rental income, or the family proximity that has been the reason you have been thinking about an ADU in the first place.
Straight answers. No runaround.
Because every trade in the building shows up, and you are building most of them from scratch in a footprint small enough that every line item is visible. Foundation, framing, roofing, plumbing, electrical, HVAC, drywall, finish carpentry, tile, cabinetry, and finishes. An ADU is one of the most concentrated construction projects you can take on. The square footage is small but the work is dense, and unlike a remodel where the existing structure does most of the work for you, an ADU builds the envelope, the systems, and the interior from zero.
Add to that the fact that ADU construction is roughly 60% labor, and skilled labor in Phoenix has gone up about 20% since 2019. ADUs are not expensive because they are complicated to look at. They are expensive because of how many people, hours, and trades it takes to build a livable second residence, to code, on a lot that already has a finished home on it.
Use the Estimator ToolAlmost never. An attached ADU and a home addition with a full bathroom cost roughly the same, because the work is structurally similar. A detached ADU is meaningfully more expensive than an addition of the same square footage because you are building a foundation, an envelope, and a roof from scratch instead of tying into the existing house.
The fair comparison is not cost. It is what you actually need. If you need extra space inside the main house (a bigger primary suite, a family room, a home office), an addition is the right answer. If you need a separate, self-contained unit with its own kitchen and bath that can house a family member, generate rental income, or function as a guest residence, an ADU is the right answer even at a higher cost. The two are answers to different questions.
Yes, significantly. A garage conversion with a kitchenette and a 3/4 bath at a clean Essential finish can land around $165,000 on a typical Phoenix lot. The same scope built as a detached new structure is closer to double that. The reason is the shell: the foundation, framing, and roof of your garage already exist, and they meet code as a structure even if the interior does not. The conversion cost is interior reconfiguration, insulation, mechanical upgrades, the kitchenette and bath buildout, and finishes. The big-ticket items on detached new construction (footing, slab, framing, exterior envelope, roofing) are mostly skipped.
The constraints are real. Your garage has to be on a footprint that works for a livable unit, the local ordinance has to allow garage conversions (most Phoenix-area cities do), and you lose the garage itself, which usually means converting it into outdoor parking. If those three things work, conversion is the cheapest legitimate path to a finished ADU.
Most of the time, yes. Arizona's 2024 HB 2720 set a statewide floor requiring cities to allow ADUs on residential lots. Phoenix, Scottsdale, Tempe, Chandler, Gilbert, and Mesa all permit them, with city-specific rules on setbacks, lot coverage, owner-occupancy, and parking. Paradise Valley is exempt from HB 2720 entirely and has its own approval process, which is more restrictive but not impossible.
Whether your specific lot qualifies depends on lot size, setback distances, existing utility capacity, and whether the lot is in an HOA that has separate restrictions (see next question). We walk through the legal and lot-specific picture in detail in our Phoenix ADU rules guide, and we confirm lot-specific eligibility during the design phase before any construction commitment is made.
HB 2720 governs cities. It does not override HOAs. If your CC&Rs (the recorded covenants, conditions, and restrictions that govern most master-planned communities) prohibit ADUs, the city's allowance does not give you the right to build one. The HOA's restriction stands.
In practice, most older Phoenix neighborhoods do not have HOAs or have HOAs with weak ADU language. Newer master-planned communities (Verrado, Eastmark, parts of Estrella) are more likely to have explicit ADU restrictions. The check is simple: pull your CC&Rs (your title company has them, or your HOA management company can send them) and search for language on accessory dwelling units, guest houses, secondary structures, or rental restrictions. If the language is ambiguous, the HOA's board has interpretive authority. Our Phoenix ADU rules guide covers the HOA layer in more detail.
Long-term rentals are allowed in most Phoenix-area cities, with the caveat that some cities require owner-occupancy of either the main house or the ADU. Short-term rentals are more variable. Arizona state law generally allows short-term rentals, but cities have layered on registration, inspection, and operational requirements. Scottsdale, Sedona, and several other Arizona cities have tightened STR rules significantly in the past few years. Some HOAs prohibit STRs entirely regardless of city allowance.
Rental income is a real and meaningful financial consideration for many ADU prospects. We avoid making specific rental income projections on this page because occupancy varies by lot, by city, and by how the rental is marketed, and a projection that does not hold up creates a worse outcome than no projection. What we can say is that an attached ADU and a detached ADU command different rental rates, finish level affects rate significantly, and a Phoenix-area Premium ADU built for long-term rental can return a meaningful portion of its construction cost over a 20-year hold period. The honest number for your specific project comes from your specific lot, your city, and current local rental comps.
For a garage conversion or simple attached ADU at Essential finish: typically 4 to 6 months of construction. For a Premium attached or small detached new build: 6 to 9 months. For an All-In detached ADU with full custom finishes and significant utility extension work: 9 to 12 months.
Design adds 10 to 16 weeks before construction starts, depending on scope, lot complexity, and city permit timeline. Phoenix-area municipalities typically take 6 to 10 weeks to issue permits on ADU work, which is longer than remodel-only permits because structural drawings, utility plans, and site plans are required. The decisions made in design are what the next 30 to 50 years of the ADU depend on. We do not rush the design phase to start construction faster.
No. The main house stays fully functional throughout an ADU build. The construction noise is real but contained to the ADU footprint, which is typically in the backyard or attached to a single side of the house. The most disruptive phase is utility tie-in (sewer extension, electric service work, sometimes water tap), which can require short service interruptions to the main house that we schedule and communicate in advance.
For garage conversions, the construction zone is the converted garage itself, which usually means losing garage access during the build. For attached ADUs with a shared wall or doorway, plan on a few days of dust control where the addition meets the house. An ADU is one of the least disruptive major projects we build, which is part of why prospects with young families and aging parents to consider often prefer it to a whole-house remodel.
Content last updated: December 2026. This page is reviewed and updated annually.
That is exactly what the estimator is for.
We built it because the most common question we get before anything else is some version of "what is this going to cost?" The estimator will not give you a contract price. No tool can do that without knowing your specific lot, your specific path (detached, attached, conversion), and the choices you are going to make on kitchen, bath, finish level, and use. What it will give you is an honest preliminary range based on the things that actually drive ADU cost: path, size, kitchen scope, bathroom scope, lot conditions, finish level, primary use, and timeline.
It takes about two minutes. Your results show up immediately after you complete the final step. No salesperson waiting on the other end of the form.
Just a number you can actually use.
Ready to talk instead? Schedule a phone call with our team.
You came to this page with a question. We hope you are leaving with something more useful than a number. A real understanding of what goes into building an ADU, what it should cost in the Phoenix and Scottsdale market, and what to look for in the team you hire to build it.
Here is what we know after 25 years of design-build work in the greater Phoenix Metropolitan Area. The homeowners who end up happiest are the ones who went into the project informed, chose their contractor carefully, and trusted the people they hired to do what they said they would do. That is not a complicated formula. It is just harder to find than it should be.
The attached ADUs and additions with kitchenettes we have built across Phoenix and Scottsdale share every component of the detached units we build today. Foundation work, framing, the mechanical and electrical systems, the kitchen and bath buildouts, the finishes, the city permitting, the way it all integrates into a finished neighborhood lot. This is the work we have always done.
Building an ADU on a property you love is one of the most consequential decisions you will make as a homeowner. The unit you build becomes part of how your family lives, hosts, or earns for the next 20, 30, or 50 years. The contractor you pick to build it should be someone whose work will still be standing, watertight, and beautiful when your grandkids visit the home you raised your kids in.
We have been doing this since 2001. We would love to add your ADU to the list.
