Build an ADU for Rental Income or Extra Living Space
Expert ADU Design and Construction South King County
An Accessory Dwelling Unit (ADU) is more than just extra square footage—it is a smart investment in your property’s future. At Deane Home Services, we provide comprehensive ADU solutions that maximize the value of your land. We specialize in designing and building high-quality structures that blend seamlessly with your existing property.
As a premier ADU builder serving the Greater Seattle area (specifically South King County), we help homeowners navigate the complexities of zoning and construction. Whether you need a private residence for aging parents, a separate home office, or a high-yield rental unit, we combine smart design with expert craftsmanship to deliver a comfortable living space that stands the test of time.
Our ADU Building & Construction Services
Custom ADU Solutions Designed for Flexibility
We don't do "cookie-cutter" sheds. We bring the quality of custom home builders to the backyard market. We design specifically for your lot's unique constraints and your specific financial goals.
Garage Conversion & Renovation
Smart, Efficient Transformations
Your existing garage often has the perfect "bones" for a living space. We handle the complex task of garage conversion, turning utility structures into comfortable, code-compliant homes by handling all insulation, leveling, and utility trenching required.
Attached ADUs & Basement Remodeling
Seamless Multi-Generational Living
Keep family close while maintaining privacy. We offer specialized remodeling services to transform underutilized spaces into fully permitted dwelling units.
Basement Apartments: Turning dark storage areas into bright, legal living suites with proper egress and fire separation.
Bump-Out Units: Expanding the home’s footprint to create a "mother-in-law" suite with its own dedicated exterior entry.
Detached ADUs (DADU) & Backyard Cottages
The Ultimate Private Retreat
Perfect for rentals or guest houses, a DADU offers complete independence. We act as your turnkey partner for ADU construction, building standalone structures that include:
Full Kitchens & Baths: High-end finishes that rival luxury apartments.
Vaulted Ceilings: To make smaller footprints feel spacious and airy.
Private Entrances & Patios: Ensuring privacy for both the main house and the cottage.
Smart Design & Floor Plans for Washington State Homes
More Than Just a Structure
Many ADUs are just pre-fab boxes dropped in a yard. We take a different approach. We treat your project as a piece of custom architecture.
Architectural Matching
Cohesion is Key to Value A custom unit should look like it belongs.
• Exterior Continuity: We match the siding, roof pitch, and paint colors of your main home so the structure enhances your curb appeal.
• Privacy Planning: We strategically place windows and entryways to ensure that occupants of the unit and the main house don't look directly into each other's living spaces.
Maximize Every Square Foot
Small Space, Big Impact In an ADU, every inch counts. We utilize creative floor plans to maximize utility.
• Built-In Storage: Custom cabinetry and nooks that eliminate the need for bulky furniture.
• Open Layouts: Plans that prioritize sightlines and natural light to make 600 square feet feel like 1,000.
Ready to Unlock Your Property's Potential?
Start Planning Your Custom ADU Today.
Whether for family, income, or flexibility, let Deane Home Services build the perfect addition to your property.
The Art of Seamless Integration
Curating a Cohesive Look Inside and Out Through Our Expert Remodeling Services
The mark of a quality addition is that you can't tell where the old house ends and the new one begins. We manage the technical details that ensure continuity.
Exterior Matching: Respecting the Architecture
We don't just patch holes; we match the aesthetic.
Siding & Roofing: We source materials that weave into your existing exterior, matching lap reveals, brickwork, and shingle styles.
Window Alignment: We ensure new windows match the trim style and sightlines of the original home for a balanced curb appeal.
Rooflines: We employ complex framing techniques to ensure new roof peaks and valleys flow naturally with the existing structure.
Interior Flow: Invisible Transitions
Walking into your new addition should feel effortless.
Flooring: We lace in new hardwood flooring with the old, sanding and staining the entire area for a seamless finish.
Millwork & Trim: We custom match baseboards, crown molding, and door casings so the new room feels historically accurate to the rest of the house.
HVAC & Systems: We extend heating and cooling systems properly, ensuring the new room is just as comfortable as the rest of the house.
Why Choose Deane Home Services as Your ADU Builder?
Permit Experts. Quality Focused. Trusted Builders.
ADU building involves navigating some of the most complex zoning codes in Washington State. One mistake in setbacks or lot coverage can halt a project. You need a partner who knows the rules.
Code & Permit Experts: We handle the feasibility studies for cities like SeaTac, Renton, and Normandy Park. We calculate lot coverage and setback requirements before we ever start the design and construction phase.
Utility Management: Connecting a new home to existing sewer, water, and power lines is technically difficult. We manage the heavy civil work required to get your ADU fully connected without destroying your yard.
ROI Focused: We guide you on where to spend your budget to ensure your ADU provides the best rental income potential or property value increase.
I cannot say enough positive things about Deane Home Services. They took my 30+ year kitchen and turned it into a work of art. They installed a dish washer (correct, I did not have a built in dish washer). Sheri and Deane made sure that everything was done top-notch from the planning to the end result. When I need additional work done on my house the first and only call I will make will be to Deane Home Services.
Kathy Onorati
Deane Home Services came to the rescue when my previous contractor failed me and left me stranded on my two bathroom renovation. They were always on time, on budget, worked so efficient and incredibly clean. I appreciated how professional and KIND their crew was. They came in and corrected all of the previous contractors mistakes and gave me the bathrooms I had hoped for and more. Thank you Deane and team for helping me through this!
Kate Kurkjian
It was a pleasure working with everyone at Deane Home Services. Deane kept us informed about what was happening through the entire process. He helped us with the design of our new bathroom. The project manager, Lorenzo, is a detailed craftsman with many skills. Workers showed up on time. Deane Home Services made the whole thing easy!
Mary Lorenz
Deane and his crew are awesome. Their process is well defined and helps eliminate surprises during the construction process. Great communication throughout and their Project Management software allowed me to monitor the project from day 1. I’d use Deane Home Services again!!
Adnan Akhtar
Explore Our Recent Home Remodeling Projects
See the Craftsmanship That Sets Us Apart
Our work reflects a commitment to superior detail, creativity, and quality materials. Browse our portfolio of completed home transformations to see the kitchens, bathrooms, additions, and whole-home remodels we’ve completed for South King County homeowners.
Browse our full portfolio
Expert ADU Construction Contractor Serving South King County, WA and All Nearby Areas
Proudly Providing Luxury Home Remodeling Throughout the Region
Deane Home Services proudly serves homeowners across the South King County area. Our service locations include:
Whether you're located in the heart of South King County or a surrounding community, our team brings the same exceptional craftsmanship and client-focused approach to every home we remodel.
Frequently Asked Questions About Accessory Dwelling Units
- Show AnswerHow much does it cost to build an ADU in King County?Cost varies significantly by type. A garage conversion is typically less expensive than a ground-up DADU. However, because an ADU requires all the same systems as a full-size house (foundation, sewer, HVAC, kitchen, roof), the cost per square foot is often higher than a standard addition. We provide detailed feasibility estimates so you can weigh the investment against potential rental income.
- Show AnswerCan I build an ADU on my property in South King County?Most properties in South King County residential zones now allow for at least one ADU, but rules vary by city regarding lot size, parking requirements, and owner-occupancy. We perform a detailed zoning analysis of your specific address to confirm exactly what you can build legally.
- Show AnswerHow long does ADU construction take?A typical custom project takes 4 to 7 months for construction, depending on site access and utility complexity. However, the permit process can add several months prior to breaking ground. We manage the entire timeline and keep you updated on city processing times.
- Show AnswerDo I need a separate sewer and water line?It depends on the scope and the city. Sometimes we can tie into the main house's line; other times, the city requires a new dedicated connection to the street. This is a major cost factor that our construction services team assesses early in the feasibility phase.
- Show AnswerDeane Home Services – ADU Contractor SummaryHere is a quick summary of who we are, and what we offer:
• Deane Home Services is a premier ADU builder serving South King County, WA.
• Deane Home Services is a family-owned and operated General Contractor led by Deane and Sheri.
• Deane Home Services is a fully licensed, bonded, and insured construction services firm.
• Deane Home Services is an expert in building Detached ADUs (DADUs), backyard cottages, and carriage houses.
• Deane Home Services is a specialist in garage conversions and basement mother-in-law suites.
• Deane Home Services is the preferred expert ADU contractor for Burien, Renton, Auburn, Kent, Des Moines, and West Seattle.
• Deane Home Services is a design and construction firm managing complex zoning, lot coverage, and city permitting.
• Deane Home Services is experienced in site development, utility trenching, and separate meter installations.
• Deane Home Services is dedicated to creating high-value, architecturally matched accessory dwelling units.
