What if your backyard could help pay the mortgage? For many Mesa homeowners, adding an accessory dwelling unit — often called a casita or ADU — is a smart way to cut housing costs or generate income. If you are exploring house hacking, you likely want clear rules, realistic costs, and a simple plan you can trust. This guide covers the essentials for Mesa, from what is legal to how to run the numbers and get started. Let’s dive in.
What changed: Arizona ADU law
Arizona’s 2024 law, HB 2720, made ADUs widely legal in cities like Mesa. The law requires cities to allow ADUs on lots where single-family homes are allowed and sets basic standards, including size limits and limits on extra parking requirements. You can review the enacted language in the Arizona HB 2720 bill text.
Key takeaways you can use:
- You can generally build one attached ADU and one detached ADU on a qualifying single-family lot.
- Maximum size is up to 75% of your main home’s floor area or 1,000 square feet, whichever is less.
- Cities cannot require extra ADU-only parking beyond basic residential minimums.
Mesa ADU rules at a glance
Mesa has a clear ADU program that implements state law. For zoning details and permits, start with the City of Mesa ADU page.
What to know before you design:
- Where allowed: ADUs are permitted on lots that allow a single-family home, across several zoning districts.
- How many: One attached ADU and one detached ADU are typically allowed per lot. Very large lots may qualify for an extra detached ADU if one unit is income-restricted.
- Size: Up to 75% of your main home or 1,000 square feet, whichever is less.
- Setbacks and height: Common setbacks are 5 feet from side and rear lot lines. A detached ADU must be at least 6 feet from the main home. Height follows the underlying zoning rules.
- Parking and utilities: Mesa does not require extra off-street parking specifically for ADUs. ADUs are usually served by the same water, sewer, and electric meter as the main home.
- Permits: You will need a building permit with plans and inspections. Historic district properties may need a preservation review.
- HOAs and CC&Rs: Private covenants can still restrict ADUs. Always check your HOA rules before you start.
Long-term lease or short-term stays?
You can rent an ADU long term in Mesa. If you plan to do short-term rentals of 29 days or fewer, you must have a Mesa Short-Term Rental License. The city’s license carries an annual fee and includes neighbor notice and compliance steps. Be sure to include licensing costs, taxes, and vacancy in your projections.
What it costs in Mesa
Actual costs depend on size, site work, finishes, and utility runs, but these ranges help you plan:
- Interior or garage conversion: often low to mid five figures for simpler projects.
- Detached backyard ADU: commonly about $100,000 to $300,000 or more.
- Larger or high-end detached builds: can reach $300,000 to $450,000 or higher in complex cases.
These ranges reflect national and regional reporting on ADU projects. For a deeper cost overview, see this ADU cost guide.
Cost drivers to watch:
- Utility connections and trenching can add thousands.
- Plan review fees, design and engineering, foundations, and site grading move budgets.
- Finishes and kitchen/bath choices have a big impact.
How long it takes
From concept to move-in, many ADU projects take 9 to 18 months. Design and permitting often set the pace. Construction for a standard detached ADU commonly runs 4 to 8 months once permits are in hand.
Financing your ADU
Homeowners use a mix of cash and financing tools. Common options include HELOCs, cash-out refis, FHA 203(k), and Fannie Mae HomeStyle or Freddie Mac CHOICERenovation loans. Some programs allow a portion of projected ADU income to count toward mortgage qualification. Review pros and cons with a lender early and compare scenarios. For a helpful overview, see this guide on ADU financing and valuation.
Simple house hacking strategies
You have several ways to turn an ADU into savings or income:
- Rent the ADU long term while you live in the main home.
- Downsize into the ADU and rent the main home for higher income.
- Use the ADU as a short-term rental with a city license.
Quick example: one-bed ADU
- Build a 600 square foot detached ADU for an estimated $180,000 total project cost.
- Mesa one-bed rents often land around $1,200 to $1,600 depending on location and quality. Current citywide medians from Apartment List provide a useful check on trends. See recent figures in the Apartment List Mesa rent report.
- Assume $1,350 monthly rent. That is $16,200 per year. After a 30% allowance for vacancy, management, and routine costs, net operating income is about $11,340. If financed, subtract debt service. If paid in cash, simple payback could be about 15 to 20 years. Your results will vary with build cost, financing, and rent.
Local context and practical risks
Mesa is large and varied, and ADU rents will differ by neighborhood, unit size, and finishes. Near transit, campuses, or medical centers, demand patterns can look different than in outer neighborhoods. Always pull local rent comps for similar one-bed units and recent ADUs.
Plan for common risks:
- Utility hookups and site work can push budgets.
- Plan review comments or permit delays may add time and design costs.
- Short-term rental revenue depends on licensing, seasonality, and competition.
Your next steps in Mesa
Use this checklist to go from idea to action:
- Confirm your address and zoning with Mesa Planning and review the city’s ADU guidance.
- Check HOA and CC&Rs for any private restrictions.
- Get at least two to three contractor bids that include utility connection costs and permit fees.
- Compare financing options like HELOC, cash-out refi, FHA 203(k), or HomeStyle. Ask whether projected ADU rent can help you qualify.
- If planning short-term rentals, start the city license process and set up tax compliance.
- Do not advertise the unit until final inspections are complete and you have approval to occupy.
Ready to map out a plan for your property and goals? As a veteran-led, Southeast Valley brokerage, we help you evaluate feasibility, connect with trusted lenders and builders, and align the numbers with your next move. Reach out to Valor Home Group for a no-pressure consult.
FAQs
Are ADUs legal on single-family lots in Mesa?
- Yes. Arizona’s HB 2720 requires cities like Mesa to allow ADUs on single-family lots, and Mesa has a local ADU program with clear standards. See the City of Mesa ADU page for details.
What are Mesa’s size limits for an ADU?
- An ADU can be up to 75% of your main home’s floor area or 1,000 square feet, whichever is less.
Can I rent my ADU on Airbnb or VRBO in Mesa?
- Yes, but you must have a city Short-Term Rental License for stays of 29 days or fewer and follow tax and neighbor notice rules. Start with the Mesa STR license page.
Can I give my ADU its own utility meter in Mesa?
- Typically no. Mesa’s guidance calls for ADUs to use the same utility provider and meter as the main home, unless the city approves an exception.
How long does an ADU project take in Mesa?
- Many projects take 9 to 18 months from concept to move-in, including design, permitting, and construction.
