Building an ADU in Scottsdale: A Complete 2025 Guide

Scottsdale, with its sun-drenched landscapes and luxury lifestyle, has long been a destination for those seeking a premium living experience. For homeowners, that experience is no longer limited to the main house. Thanks to recent changes in Arizona state law and local city ordinances, adding a chic, functional Accessory Dwelling Unit (ADU)—often called a casita or guest house—to your property has never been more straightforward. This is a game-changer for Scottsdale families looking for flexible living space, a source of rental income, or a private retreat for guests.

But navigating the new rules can feel daunting. That’s why we’ve created this complete 2025 guide. We'll walk you through Scottsdale’s specific regulations, from zoning eligibility to permit requirements, and show you how a foundation-built tiny home can transform your backyard and boost your property value.

Understanding Scottsdale's ADU Rules: What is Ordinance 4687?

For years, building a guest house in Scottsdale was a complex and often restrictive process. That all changed with Arizona House Bill 2720, a statewide mandate requiring cities with over 75,000 residents to streamline their ADU regulations. In response, the City of Scottsdale adopted Ordinance 4687, which officially went into effect to align local laws with the new state requirements.

This ordinance is the new playbook for homeowners. It lays out the specific casita rules for Scottsdale, defining what you can build, how large it can be, and where it can be placed. The goal was to increase housing flexibility while preserving the character of Scottsdale's beautiful neighborhoods. The result is a clear set of guidelines that empowers property owners to add incredible value and utility to their homes.

Step 1: Determining Your Property's ADU Eligibility (Size & Zoning)

Before you start dreaming of quartz countertops and walk-in showers, the first step is to confirm your property is eligible. Under the new rules, most single-family residential lots in Scottsdale now qualify for at least one ADU.

Zoning and Location

First, confirm your property is zoned as single-family residential. The new ordinance applies broadly to these lots. However, there are some key exceptions. For example, properties located within specific high-noise zones near Scottsdale Airport may be excluded from the new ADU allowances. For a detailed breakdown of zoning in your specific neighborhood, you can review the latest information on our comprehensive Scottsdale ADU resource page.

Size and Setbacks

Ordinance 4687 provides generous size limitations designed to accommodate a comfortable living space:

• Maximum Size: Your ADU can be up to 1,000 square feet or 75% of the gross floor area of your main house, whichever is less.
• Example: If your primary home is 2,500 sq. ft., 75% of that is 1,875 sq. ft. Since that exceeds the cap, your ADU is limited to 1,000 sq. ft. If your home is 1,200 sq. ft., 75% is 900 sq. ft., so your ADU can be up to 900 sq. ft.
• Minimum Setbacks: State law dramatically reduced setback requirements. Your new ADU only needs to be five feet from the rear and side property lines, opening up possibilities for lots of all shapes and sizes.

Step 2: Navigating Permits, Utilities, and Site Prep

Once you’ve confirmed eligibility, the next phase involves the practical logistics of planning and construction. While the new ordinance makes it easier to get approval, building a permanent structure still requires careful planning and adherence to city codes.

Building Permits

An ADU is a real home, and it requires a building permit just like any other residential construction project. You will need to submit detailed plans to the City of Scottsdale for review. These plans must demonstrate compliance with the International Residential Code (IRC), including standards for structural integrity, electrical, plumbing, and safety. This ensures your new guest house is built to the highest quality standards.

Utilities

Scottsdale's ordinance requires your ADU to have separately metered electrical and gas utilities. However, for water and sewer, you are typically allowed to connect to your main home’s existing lines. This provision saves homeowners significant costs and complexity, as it avoids the need for entirely new connections from the street.

Site Preparation

Preparing your backyard involves ensuring proper access for construction, grading the site for the foundation, and trenching for the utility lines. Working with an experienced builder like Clever Tiny Homes helps streamline this process, ensuring your site prep is done efficiently and correctly from the start.

Considering the investment? Many homeowners explore ADU financing in Arizona through options like a home equity line of credit (HELOC), a cash-out refinance, or a construction loan. Having a clear plan for permits and site prep is essential when speaking with lenders.

Step 3: Choosing the Right Foundation-Built Tiny Home Model

This is where your vision truly comes to life. The key to complying with Scottsdale law—and maximizing your investment—is choosing a high-quality, foundation-built tiny home. Unlike a Tiny Home on Wheels (THOW), which is legally considered an RV and cannot be lived in permanently in a Scottsdale backyard, a foundation-built ADU is a permanent home that adds lasting value to your property.

Clever Tiny Homes models are designed to meet the aesthetic and quality demands of the Scottsdale market. With features like:

• Open-concept floor plans and high ceilings that create a spacious feel.
• Massive windows that flood the interior with natural light and connect to the beautiful desert landscape.
-Premium finishes like quartz countertops, luxury vinyl plank flooring, and soft-close cabinetry.
• Spa-like bathrooms and full-sized appliances for a truly comfortable living experience.

Are you weighing the benefits of a permanent backyard structure against a more mobile solution? Our guide, Scottsdale Tiny Home: Backyard ADU vs. 55+ Resort?, explores the pros and cons of each lifestyle.

Factoring in HOAs: The Hidden Hurdle for ADU Construction

This is a critical point for many Scottsdale homeowners. While Arizona's state law and Scottsdale's Ordinance 4687 create a legal right to build an ADU, they do not override private restrictive covenants enforced by a Homeowner's Association (HOA). Many of Scottsdale's most desirable neighborhoods are governed by HOAs with strict rules about new construction.

Before you invest in plans or site work, you must:

1. Obtain a copy of your HOA’s Covenants, Conditions, and Restrictions (CC&Rs).
2. Carefully review the sections related to outbuildings, guest houses, or new construction.
3. Submit your plans to your HOA’s architectural review committee for approval.

Getting written approval from your HOA is a non-negotiable step in the process.

The Scottsdale Owner-Occupancy Rule for Short-Term Rentals

Scottsdale's ordinance includes an important provision to maintain neighborhood stability: an owner-occupancy requirement for short-term rentals (STRs). The rule is simple: if you plan to rent out either your main home or your new ADU on a short-term basis (like on Airbnb or Vrbo), the property owner must live on-site in the other unit.

This regulation prevents properties from becoming absentee-owned "party houses" and ensures a resident is always present. For homeowners, this makes an ADU a perfect "house hacking" opportunity—you can generate significant rental income from your backyard casita while continuing to enjoy your primary residence.

How a Clever Tiny Home ADU Maximizes Your Property Value

To build a guest house in Scottsdale, AZ, is to make a smart, future-focused investment. A beautifully designed, fully permitted ADU offers a powerful combination of lifestyle flexibility and financial return.

It can serve as a private home for aging parents, a launchpad for adult children, a dedicated home office, a creative studio, or a high-demand rental unit. In a market like Scottsdale, a 1,000-square-foot luxury casita with its own entrance and amenities can add substantial value to your property’s appraisal and overall appeal.

For seasonal residents who might not own land in Scottsdale, a luxury park model in a dedicated community offers another incredible pathway to small-footprint living. Discover more in our guide, Scottsdale Snowbirds: A Guide to Luxury Park Model Living.

The new era of ADUs in Scottsdale is here, and the possibilities are exciting. Ready to explore the potential for your property? Contact the Clever Tiny Homes team and review the latest Scottsdale ADU requirements with our local experts today.

Authoritative Resources:

• City of Scottsdale: Official Ordinance 4687 PDF
• Your Valley News: Scottsdale Council Passes ADU Ordinance
• Arizona Legislature: HB 2579 (Related Housing Bill)