ADU Construction - Seattle, WA

ADU Construction - Seattle, WA

The extra living space you need from an accessory dwelling unit contractor you can trust

At Northlight Custom Builders, we specialize in building accessory dwelling units (ADUs). Whether you’re looking for extra space for aging in place family members, home office space, or even a small apartment, ADUs are the perfect solution. ADUs are self-contained living spaces that can be built beside your existing home or on top of it, whatever works best for you. We understand that accessory dwelling units are a big investment, so we will work diligently within your budget guidelines without sacrificing quality. Our team will provide accurate estimates and consult with you on how to make your ADU as affordable as possible without compromising its long-term value or structural integrity. If you’re ready to make your accessory dwelling unit dreams a reality, get in touch with Northlight Custom Builders today. We look forward to helping you create the extra living space you need and deserve.

Choose Your Trusted Local General Contractor

We’re proud to have served clients throughout Northern Washington for over 26 years. Our accessory dwelling units are crafted with the same attention to detail as every other project we take on and we always strive for 100% customer satisfaction. We’re not done until you’re completely satisfied with your ADU! Our construction team will create an ADU that meets all local zoning and building code requirements. We'll work with you every step of the way, from designing a layout to choosing materials and finishes to ensure your accessory dwelling unit looks great and is built to last. Our experienced professionals are fully licensed, insured, and bonded, and we guarantee our work for your peace of mind.

Who We Are

Northlight Custom Builders is a family-owned and operated business that has been serving the needs of homeowners in Northern Washington for over 26 years. We're a custom home builder and home remodeler with a reputation for quality, integrity, and customer satisfaction. We're not happy until our clients are completely satisfied with their new home or remodeling project, and we'll go the extra mile to make sure you get exactly what you want.

Tony Collins
The Benefits of Building an ADU

The Benefits of Building an accessory Dwelling Unit (ADU)

ADUs offer a variety of benefits for homeowners, renters, and the community at large. They are a great way to increase the livable space on your property while simultaneously increasing the value of your home.

Some of the key benefits of accessory dwelling units include:

  • Extra living space: ADUs provide an extra bedroom, office space, or even a separate living unit for family members who might be aging in place.
  • Increased rental income: ADUs can provide a secondary source of income by renting out the unit to tenants.
  • Increase your property value: Adding an ADU to your existing property can help increase your property value for later resale.

Contact Us Today!

If you're looking for a general contractor in Northern Washington who specializes in accessory dwelling units, look no further than Northlight Custom Builders. We're proud to have served clients throughout Northern Washington for over 26 years, and our accessory dwelling units are crafted with the same attention to detail as every other project we take on. Get in touch with us today and let's start planning your accessory dwelling unit! We look forward to helping you create the extra living space you need and deserve.

What Makes Us Different

What Makes Us Different?

At Northlight Custom Builders, we believe that your home should be uniquely tailored to your individual lifestyle and needs. That's why we offer fully customizable homes and remodeling services. Whether you're looking for a brand new home or just need some updating done, we can work with you to create a design that's perfect for your taste.

Diverse Customization Options

Our accessory dwelling units come in a variety of sizes and styles. We can help you create a detached ADU in your backyard or opt for an attached ADU built on top of or beside your existing home. Our team will work with you to design the perfect accessory dwelling unit that fits into your lifestyle and budget.

Excellent Craftsmanship

At Northlight Custom Builders, we take pride in our craftsmanship. Our experienced and accredited professionals use only the highest quality materials and products to ensure your accessory dwelling unit stands up to the test of time and looks great. We guarantee our work so you can have peace of mind knowing that your accessory dwelling unit will be safely built by an experienced professional who takes pride in their work.

Contact Us Today

We believe that accessory dwelling units are a great way to add extra living space and value to your home. Whether you're looking for an extra bedroom, office space, or even a separate apartment, we can design and build the ADU of your dreams. Get in touch with Northlight Custom Builders today to learn more about accessory dwelling units and how they can meet your needs. We look forward to helping you create the accessory dwelling unit of your dreams!



Northlight is dedicated to bringing highly knowledgeable and skilled teams to your project. We are one of a few home builders in the state of Washington that holds the Certified Builder accreditation from the Business Industry Association of Washington (BIAW). What stands a BIAW builder apart from any other? “A Certified Builder is proven, accountable, and vetted by one of the largest home building associations in the country.”

In addition to BIAW, our team maintains multiple accreditations and certifications that hold us accountable for exceptional craftsmanship and demonstrate our above-and-beyond performance for customers.


  • National Association of the Remodeling Industry
  • Master Builders Association of King and Snohomish Counties
  • BuilderTrend
  • National Association of Home Builders
  • Edmonds Chamber of Commerce


say about our services

William B. 2/18/2024

This has been a fantastic process front to back. From the first meeting to the final product was delivered we were fully satisfied. The team really listened to what we wanted for the space and met every request. We love the final result. I would also like to commend Autumn. She was amazing. Kept us fully informed about what was going to happen and was always cheerful and willing to spend time talking to us about the project. I would ... continue reading

Kurt N. 11/18/2023

NorthLight Custom Builders is the real deal, and exceeded all our expectations for our bonus room remodel. Tony and his team operate by creating a project plan and detailed estimate before they begin, so there are no surprises or delays. This exercise outlines all of the tasks and milestones from start to finish. In every instance, NorthLight was on time, on spec and complete. All of their workers are professionals in their trade producing ... continue reading

Joe Cross Real Estate 10/11/2023

We used Northlight for a project to open up our loft space and to also install a coffee bar. Craig was awesome and did great work, detailed and thorough. Sean also found the most awesome fold-out staircase for our loft access, which has been an absolute game changer for our home!

The ADU Building Process

  • Show Answer Step 1: Let’s talk about your project
  • Once our consultation meetings are complete, we’ll present a Design Agreement for review and approval. The Design Agreement will include renderings, detailed plans such as architectural drawings and elevations; that will all be used in the Construction phase of the project. We’ll also introduce you to our selection of products such as cabinetry, tile, flooring, fixtures and more - allowing you to personalize your home exactly how you want it.
  • When the Design Agreement is signed, we will begin to dig into the details of your project. We will take precise measurements, check on needed permits, talk with subcontractors and start the process of making your selections. Whether you are remodeling a kitchen, bathroom, a whole home addition, or adding a new space; you will have selections to make for your flooring, light fixtures, cabinetry, paint colors, and more. For some this is a fun process, for others it can be overwhelming. Whichever camp you fall into, we are here for you. We have in-house design specialists that will help you every step of the way. Whether you just need someone to bounce ideas off, or if you want us to meet you at the store and help you pick out the best fixtures, flooring and more that will be functional and beautiful in your new space; we are here for you!
    Once you have your selections made, we will incorporate those into a project rendering for you. This will allow you to visually see how your space design and selections will look prior to work beginning.
  • The construction process begins with laying the foundation and then moves on to framing, insulation, siding, and other finishing touches. Throughout the process, our team of experienced professionals will ensure that your accessory dwelling unit is built to last - all while maintaining the highest quality standards and workmanship.
  • Once construction is complete, we'll conduct a final inspection to make sure everything meets local zoning and building codes. We'll also make sure that your accessory dwelling unit looks great and functions properly.
    After the final inspection is complete, you can move into your accessory dwelling unit and start enjoying all of its benefits! Your ADU will be a beautiful and functional new living space to use and enjoy.

Step 6: Enjoy your brand new home!

At the completion of your Design-Build remodeling project, we’ll do a final walkthrough with you to ensure everything is up to Northlight Custom Builders standards! Once complete, you can rest assured knowing that your Design-Build project is covered by our industry-leading warranty for our workmanship. We will also provide you with maintenance tips for any new surfaces in your home.

Other Home Construction Services We Provide

General Contracting Services for Every Home Construction Need

As a design to build general contractor, we are both expert home remodelers and custom home builders! This makes us uniquely suited to handle accessory dwelling unit construction and all other types of home improvement projects. In addition to ADU construction, we also provide:

Get started on your ADU today!

At Northlight Custom Builders, we understand the importance of accessory dwelling units and are committed to providing quality services for all of our ADU building projects. Contact us today for more information about accessory dwelling unit construction - and get started on creating your dream accessory dwelling unit!

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