ADUs in San Tan Valley: What Homeowners Need to Know Before Building a Casita or Guest House

San Tan Valley is one of Arizona's most exciting growth communities — and thanks to sweeping new state law, its homeowners now have powerful new rights to build accessory dwelling units (ADUs) on their properties.

Revival Contracting is here to help you use them.

What is an ADU — and why is San Tan Valley the perfect place to build one?
​An accessory dwelling unit (ADU) is a fully self-contained living space built on the same lot as your primary home. You may know it by another name: casita, guest house, in-law suite, granny flat, or backyard cottage.
Whatever you call it, an ADU comes with its own sleeping area, bathroom, kitchen, and separate entrance — making it a fully independent home that just happens to share your land.

San Tan Valley is uniquely well-suited for ADUs. Lots here tend to be larger than those in more built-out East Valley cities like Chandler or Tempe, giving homeowners the yard space to accommodate a detached casita with room to spare. The community also skews heavily toward multigenerational families — exactly the people an ADU serves best.

San Tan Valley & Pinal County ADU rules: what changed in 2025 and 2026
San Tan Valley is an unincorporated community in Pinal County, which means it falls under county zoning — not a city's. This distinction matters when it comes to ADUs, because the law that originally expanded ADU rights (HB 2720, passed in 2024) applied only to cities with populations over 75,000. San Tan Valley was not included at that time.

That changed with HB 2928, signed into law on May 23, 2025. This follow-up legislation extended essentially the same ADU rights to Arizona counties — including Pinal County. The Pinal County Board of Supervisors voted to update their Development Services Code ahead of the January 1, 2026 deadline, renaming "guest houses and casitas" as ADUs and aligning local rules with the new state standards.
PINAL COUNTY ADU RULES AT A GLANCE

• At least one attached and one detached ADU is permitted on any residentially zoned lot
• ADUs may not exceed 75% of your primary home's square footage, or 1,000 sq ft — whichever is smaller
• Minimum ADU size is 200 sq ft; must have a separate exterior entrance
• Side and rear setbacks cannot exceed 5 feet
• The county cannot require the ADU to match your home's exterior design, roof pitch, or finishing materials
• No additional parking required solely because of an ADU
• The ADU and primary home share a utility meter and a parcel address (but the ADU gets its own unit number for emergency access)
• If your ADU uses a septic system, the county may require it to be properly sized before construction begins
• Manufactured homes, mobile homes, and RVs generally cannot serve as ADUs (with limited exceptions for larger lots)
• HOA CC&Rs may still apply — check your community's governing documents

What kinds of ADUs can Revival Contracting build in San Tan Valley?
We design and construct every type of ADU for San Tan Valley homeowners. Every project is tailored to your lot, your budget, and your goals — no prefab templates, no one-size-fits-all approach.
MOST POPULAR

• Detached backyard casita
  
  • A freestanding structure in your backyard, completely separate from the main home. Perfect for multigenerational living, long-term rental income, or hosting extended guests in style.

ATTACHED ADDITION

• Home addition ADU
  
  • Expand your home's footprint with a connected suite that has its own private entrance. Ideal for aging parents who want independence without leaving the family property.

CONVERSION

• Garage conversion
  
  • Turn a seldom-used garage into a permitted, code-compliant apartment.
    
  • One of the most cost-effective ADU paths available, using existing structure and foundation.

INTERIOR

• Interior suite conversion
  
  • Repurpose large bonus rooms, over-garage spaces, or unused square footage into a fully independent living unit — no new foundation required.

The real reasons San Tan Valley homeowners are building ADUs right now
Multigenerational living. 

San Tan Valley has always attracted families who want to stay close across generations.
An ADU lets grandparents, adult children, or other relatives live right on the property with privacy and independence — no assisted living facility, no long commutes between households.

Long-term rental income. Under Arizona and Pinal County rules, your ADU can be rented to a tenant on a long-term lease (90 days or more). With demand for rental housing in the Southeast Valley consistently strong, a well-built casita can generate meaningful monthly income while adding permanent value to your home.

Property value. A permitted, professionally built ADU is a genuine asset on your property's appraisal. Buyers increasingly seek lots with ADU potential — and a finished unit means they're paying for the improvement, not the possibility.

Larger lots. San Tan Valley's acre and half-acre lots give you the room to build a proper detached casita without crowding your yard. You don't have to squeeze a tiny structure into a tight suburban lot.
Revival Contracting designs ADUs that feel like real homes — because they are.

What to watch out for: septic systems and HOAs
Two factors are particularly important for San Tan Valley ADU projects: septic systems and HOA rules.
Many properties in San Tan Valley are not connected to a municipal sewer and rely on septic systems instead. Pinal County can require that your septic system be properly evaluated and sized before an ADU is permitted. Revival Contracting works with licensed septic professionals to assess your system early in the planning process so there are no last-minute surprises.

If your neighborhood has a homeowners association, note that Arizona state law does not override HOA CC&Rs when it comes to ADUs. Your HOA may have its own rules about secondary structures, exterior appearance, or rental use. We recommend reviewing your CC&Rs before starting design — and our team is happy to help you interpret what's there.

The Revival Contracting process for San Tan Valley ADUs
We manage the full project lifecycle, so you never have to coordinate between separate designers, permit runners, and contractors.
Our team handles everything from first sketch to final inspection.

• Free on-site consultation and ADU feasibility evaluation for your specific Pinal County lot
• Custom architectural design aligned with county code and your HOA requirements
• Complete permit application, plan submission, and county coordination
• Septic system evaluation coordination when applicable
• Full licensed and insured construction: foundation, framing, electrical, plumbing, HVAC, and finishes
• Final inspection support and certificate of occupancy

Frequently asked questions: ADUs in San Tan Valley
Can I rent my ADU in San Tan Valley?
Yes — long-term rentals are permitted under Pinal County and state law. A long-term rental is defined as a lease of 90 days or more, or a month-to-month arrangement. Short-term vacation rental rules are governed separately by state law. Check with your HOA for any additional community-level restrictions.
Does my ADU need to match my house's exterior?
No. Under HB 2928, Pinal County cannot require your ADU to match the exterior design, roof pitch, or finishing materials of your primary home. You have flexibility in how your ADU looks, as long as it meets building code requirements.
What if my property uses a septic system?
Pinal County may require your septic system to be evaluated and properly sized before your ADU permit is issued. Revival Contracting coordinates this process for you early in the project so it doesn't delay your build.
How big can my ADU be in San Tan Valley?
Up to 1,000 square feet, or 75% of your primary home's gross floor area — whichever is smaller. The minimum allowed size is 200 square feet. On parcels of one acre or more, additional ADU options may be available if one unit qualifies as affordable housing.
How long does it take to build an ADU in San Tan Valley?
Most detached casitas take 4 to 7 months from permit approval to move-in, depending on size and complexity. Garage conversions and interior conversions are often faster. Contact Revival Contracting for an estimate based on your specific project.
Do I need my HOA's permission to build an ADU?
State law does not override HOA CC&Rs. If your community has a homeowners association, review your CC&Rs before proceeding. Revival Contracting helps clients navigate HOA requirements as part of our design and permitting process.

Ready to build an ADU on your San Tan Valley property?

Revival Contracting builds casitas, guest houses, and home additions across San Tan Valley and Pinal County.

Let's talk about what's possible on your lot — no obligation.
Get a free site consultation