When space starts to feel tight, multigenerational living becomes a reality, or the idea of rental income becomes appealing—many homeowners start asking, “Should we build an ADU?”
Accessory Dwelling Units (ADUs) are transforming how families use their homes, offering flexibility, long-term value, and lifestyle freedom. But like any significant remodeling project, building an ADU comes with key decisions, from zoning and cost to use and design.
At MacCoy Home Solutions, we specialize in custom remodeling projects that reflect the way our clients truly live. Whether you’re in Edmonds, Lynnwood, or another part of Snohomish or North King County, here’s what to know before you commit to building an ADU.
What Is an ADU—and Why Are So Many Homeowners Building One?
An Accessory Dwelling Unit (ADU) is a small, fully functional home located on the same lot as your primary residence. It can be:
- Attached, like a basement conversion or garage apartment.
- Detached (DADU), like a backyard cottage or above-garage studio.
Each includes a kitchen, bathroom, and sleeping area. In short, it’s a self-contained space for living, working, or renting.
Why are they becoming so popular?
- Housing Flexibility: Perfect for extended family, aging parents, or college-aged kids returning home.
- Rental Income: Many homeowners offset their mortgage or generate steady income by renting out the unit.
- Property Value: Homes with ADUs can command higher resale prices, especially in competitive markets like Edmonds and Kirkland.
- Lifestyle Expansion: ADUs offer a quiet workspace, art studio, or private retreat—without leaving home.
A 2023 report from Freddie Mac estimates over 1.4 million homes in the U.S. now include ADUs, and that number is climbing due to housing shortages and changing family dynamics.
Is Your Property a Good Fit for an ADU?
Before you start drafting blueprints, it’s important to determine if your property can legally and practically support an ADU. Zoning and site conditions vary by city—but here are the basics we evaluate for each project in areas like Edmonds, Mountlake Terrace, and Woodinville:
Zoning & Regulations
- Most single-family zones now allow for one ADU and sometimes one DADU.
- Cities like Edmonds and Lynnwood have adopted more ADU-friendly codes in recent years.
Lot Size & Setbacks
- Detached units often need to meet minimum lot size, height restrictions, and setback requirements.
- On sloped or wooded lots, special grading or permitting may be needed.
Utilities
- Can your current systems (water, sewer, electric) support another dwelling?
- If not, trenching and connection upgrades may be required.
Parking & Access
- Some jurisdictions require off-street parking for ADUs.
- Others waive this if the property is near transit or in an urban growth area.
We highly recommend a property feasibility assessment before any design work begins, ensuring the project is viable before investing more time or money.
What’s Your Long-Term Goal for the ADU?
One of the biggest advantages of an ADU is its versatility. But to make smart design and investment choices, it helps to define how you plan to use the unit:
Multigenerational Living
ADUs offer independence and privacy for aging parents, adult children, or live-in caregivers. Consider accessibility features like no-step entries, wider doorways, or universal design.
Home Office or Studio
Tired of Zoom calls from the kitchen table? An ADU can serve as a detached, quiet workspace—or even a space for therapy sessions, fitness training, or a creative studio.
Rental Property
ADUs can generate passive income as long-term rentals or short-term Airbnb units. In Edmonds and Kirkland, local ordinances allow ADU rentals with minimal red tape.
Future Downsizing
Build the ADU for a family member now, and downsize into it later when your children take over the main home.
By clarifying your intent, we can help you design a space that meets today’s needs while planning for future chapters.
What Does It Really Cost to Build an ADU?
The cost to build an ADU in Edmonds or Lynnwood generally ranges from $250,000 to $500,000+, depending on scope, size, level of customization, and site conditions.
Key cost factors include:
- Site Conditions: Sloped terrain or tight spaces increase excavation and access costs.
- Permitting Fees: Local government fees, impact fees, and architectural reviews.
- Design & Finish Level: Luxury materials, tile work, cabinetry, and appliance upgrades.
- Labor & Supply Chain: Skilled labor and materials are currently in high demand.
We always recommend budgeting at least a 10% contingency for design upgrades or unexpected issues (like water damage or poor soil conditions)—a buffer that gives you peace of mind as the project unfolds.
If financing is a concern, know that you have options. MacCoy Home Solutions works with local mortgage professionals who help homeowners use tools like:
- Home Equity Lines of Credit (HELOCs)
- Cash-out refinancing
- Renovation or construction loans
Financing your ADU is often more accessible than people think—and the rental income potential can help cover the investment over time.
What to Expect from the Design and Construction Process
Building an ADU is not a weekend project—it’s a full construction timeline. Here’s how we guide families from concept to completion:
Discovery & Feasibility
We begin with a free Rough Order of Magnitude (ROM) estimate to help you gauge the potential scope and cost of your project as we learn more about your goals. For more complex remodels—such as those requiring feasibility assessments, structural considerations, or site-specific permitting insights—our team also offers in-depth consultation services to ensure a well-informed planning process.
Design & Planning
Every great remodel starts with a thoughtful plan—and the right design partner. While MacCoy Home Solutions does not offer in-house design services, we collaborate closely with skilled independent designers to bring your vision to life. Whether you already have a designer or need a recommendation, we’ll help build the right team for your project.
We support the design process with tools like dream boards and 3D renderings to help you visualize your space before construction begins, ensuring your remodel reflects your style, meets code requirements, and stays within budget.
Permits & Documentation
Navigating permitting and documentation can be one of the most complex parts of a remodeling project—but you don’t have to go it alone. While MacCoy Home Solutions doesn’t manage permitting in-house, we work closely with trusted professionals who specialize in site surveys, engineering, and permitting support.
Whether your project is in Edmonds, Lake Stevens, or anywhere in between, we’ll connect you with the right experts and ensure their work aligns seamlessly with our build process. Our goal is to make your project as smooth and stress-free as possible—from first plans to final walkthrough.
Construction
Our team works cleanly, efficiently, and respectfully. We install protective dust barriers, manage trades, and use tools like BuilderTrend to keep you updated daily with photos, logs, and messages.
Final Walkthrough & Warranty
Every ADU includes a 12-month craftsmanship warranty.
It’s a streamlined process—but never rushed. Your comfort and clarity matter as much as the finished space.
Final Thoughts: Building an ADU With Peace of Mind
At MacCoy Home Solutions, we believe an ADU should improve your life—not just add square footage. That’s why we bring a collaborative, transparent, and personalized approach to every project.
Whether you want to keep family close, boost your income, or future-proof your property, we’re here to guide you—with ethics, craftsmanship, and calm communication every step of the way.
Ready to Build an ADU in Edmonds?
Let’s talk about your goals and see if your property is a good fit for an ADU.
Schedule an ADU consult this summer »
Your next chapter starts with the right space—and the right partner.
FAQs About Building an ADU
How long does it take to build an ADU?
Most projects take between 9 to 12 months, including design, permitting, and construction. Permitting timelines vary by city, and custom finishes may extend the schedule.
Can I rent out my ADU?
Yes. Most local jurisdictions in Snohomish and King County—including Edmonds—allow you to rent out an ADU either long-term or short-term (depending on local rules).
What’s the difference between an ADU and a DADU?
An ADU can be attached to the main home (like a basement unit). A DADU is a Detached Accessory Dwelling Unit, typically built in your backyard. We can help you determine the right fit for your property.
