Thinking About Building an ADU? Here's What Spokane Homeowners Should Know

Accessory dwelling units have quietly become one of the most talked-about home improvement projects in Spokane. Part of that is state policy catching up with demand, Washington passed legislation requiring cities to allow more of them, and part of it is simple math: a lot of Spokane households are trying to solve for aging parents, adult kids who can't find an affordable place of their own, or a mortgage payment that could use some help. If you're weighing an ADU Spokane project for your own property, here's what you actually need to know before you call a contractor.

What Is an ADU, Exactly?

An accessory dwelling unit is a smaller, self-contained living space on the same lot as your main home. It has its own kitchen, bathroom, sleeping area, and entrance; it's a complete, independent home, just smaller. There are generally three flavors:

• Detached ADU — A standalone structure in the backyard, separate from the main house
• Attached ADU — Built onto or within the existing home, sharing a wall but with a separate entrance and no shared living space
• Junior ADU (JADU) — A smaller conversion, often within the footprint of the existing home, such as a converted garage or basement

Accessory dwelling units Spokane homeowners are building today run the full range, from converted garages to fully custom backyard cottages.

Aging Parents: A Built-In Solution for Nearby Care

One of the biggest drivers of ADU interest in Spokane is families trying to keep aging parents close without moving them into a facility. A backyard unit lets a parent maintain independence, their own space, their own routine, while family is right there if something goes wrong. It also sidesteps a hard reality of Spokane's senior housing market: assisted living and memory care can be expensive, and quality options often have waitlists. An ADU keeps a parent in the family orbit on your terms and your timeline.

Caregivers: Housing the Help You Need

For families managing a loved one with more significant care needs, an ADU can house a live-in caregiver instead of a family member. This is common with older adults who need daily support but want to stay in their own home rather than relocate. It also works in reverse, some homeowners build an ADU specifically so they can live in the smaller unit themselves while renting out or handing off the main house, simplifying their own care situation as they age.

Adult Children: A Bridge, Not a Basement Bedroom Forever

Spokane's cost of living is more affordable than coastal Washington, but it's still tough for a lot of young adults to save for a first home or even cover market rent on their own. An ADU gives adult children a genuinely separate space, like privacy, a real front door, room to build savings, without the awkwardness of sharing a bathroom with mom and dad. It's a popular option for households doing multigenerational housing Spokane style: several generations on one property, but each with their own footprint.

Rental Income: The Other Big Draw

Not every ADU is about family. A lot of Spokane homeowners are building units purely as rental income. Local one-bedroom ADUs are commonly renting in the neighborhood of $1,000–$1,450 per month, with two-bedroom units often higher, which can meaningfully offset a mortgage payment or fund the construction cost over time. A few things worth knowing if income is your main goal:

• Washington's statewide ADU law removed owner-occupancy requirements in most cases, though some local jurisdictions still have their own rules, confirm with your specific city or county before you plan around renting out both units.
• Short-term rental platforms like Airbnb may be restricted or prohibited for ADUs even where long-term renting is allowed, since cities retain the authority to limit short-term rental use.
• Spokane's rental market has historically had low vacancy, which is a point in favor of steady long-term rental demand for a well-located unit.

Spokane Regulations: What's Changed and What to Check

ADU rules in Spokane have shifted substantially in the past couple of years, driven largely by Washington's House Bill 1337, which requires cities and counties within urban growth areas to allow at least two ADUs per residential lot, in any combination of attached, detached, or converted structures. Spokane's compliance deadline for this law passed in mid-2025, so local code has already been updated to reflect it.

A few regulatory basics to know, though exact numbers vary by jurisdiction and can change:

• Size limits: The City of Spokane generally caps detached ADUs around 800 square feet (or a percentage of the primary home's size, whichever is smaller), while state law sets a floor that cities can't require ADUs to be smaller than 1,000 square feet in many cases, the two rules interact, so your exact allowable size depends on your parcel and zoning.
• Setbacks and height: Detached units typically face front, side, and rear setback requirements, along with height limits, often somewhere in the high teens to low twenties in feet, depending on jurisdiction.
• Parking: Many Spokane-area jurisdictions have relaxed or eliminated additional parking requirements for ADUs in recent years, though this still varies by location.
• Permitting: Expect a review timeline of roughly two to two and a half months and permit fees in the low thousands of dollars, on top of construction costs.
• Jurisdiction matters: Rules differ between the City of Spokane, Spokane Valley, and unincorporated Spokane County, so the first step in any ADU project is confirming exactly which jurisdiction governs your parcel.

Because this area of code has been moving fast, don't rely on anything you read online, including this post, as final. Confirm current setback, size, and permitting requirements directly with your city or county planning department before you finalize a design.

Property Value: What an ADU Actually Does for Resale

An ADU is one of the few home improvement projects that can pay for itself twice, once through rental income or family use while you own the home, and again through added resale value. Buyers increasingly search for properties with existing income potential or built-in flexibility for aging parents or adult children, which can widen your buyer pool at resale, similar to how single-level and multigenerational-friendly features have become more sought-after in Spokane's current market.

That said, ADUs aren't free money. Detached construction in Spokane commonly runs somewhere in the six-figure range, and a poorly designed or poorly located unit won't add value proportional to its cost. Talk to a local agent about how comparable ADU-equipped properties have actually sold in your neighborhood before you assume the math works in your favor.

Getting Started

If you're seriously considering an ADU, the practical first steps are:

1. Confirm your jurisdiction and zoning — city of Spokane, Spokane Valley, or unincorporated county, since each has its own current rules.
2. Talk to your local planning department before you commit to a design, to confirm size, setback, and parking requirements for your specific lot.
3. Decide your primary goal — family housing, caregiver space, or rental income, since that will shape everything from layout to whether you need a full kitchen or a kitchenette.
4. Get a realistic cost estimate from a local contractor, and compare it honestly against what the unit will save or earn you over time.

Final Thoughts

Between recent state legislation opening up ADU rules and the very real pressures of caring for aging parents, housing adult children, or simply needing extra income, it's no surprise ADUs have become one of the most active conversations in Spokane real estate right now. The regulations are more permissive than they used to be, but they're also genuinely local and still evolving — so the right first move is a phone call to your city or county planning office, not a shovel in the ground.

Considering an ADU and want to know how it could affect your property's value, or looking for a property with existing ADU potential? Reach out, we can walk you through what's realistic for your specific lot.