Seattle DADU Construction
Seattle DADU construction adds value, rental income, and flexible living space to your property.
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Building a DADU in Seattle, WA
Detached accessory dwelling units (DADU) are small, standalone houses built behind your main home. They allow you to maintain your privacy and all the square footage in your main house while creating extra living space.
New Image Construction Management is an expert at building DADUs in the Seattle Area.
Pre-Designed DADU Floorplans
Anita DADU
Anna DADU
Ariana DADU
Ayva DADU
Diana DADU
Elena DADU
ESABELLA DADU
INNA DADU
JULYETTA DADU
LILY DADU
MARGO DADU
Milana DADU
PAISLEY DADU
Schooner DADU
SOFIYA DADU
STELLA DADU
VICTORIA DADU
Anita DADU
Anna DADU
Ariana DADU
Ayva DADU
Diana DADU
Elena DADU
ESABELLA DADU
INNA DADU
JULYETTA DADU
LILY DADU
MARGO DADU
Milana DADU
PAISLEY DADU
Schooner DADU
SOFIYA DADU
STELLA DADU
VICTORIA DADU
1103 Henderson DADU
820 Rose Street DADU
5409 37th Ave DADU
WHAT IS A BACKYARD COTTAGE?
A Backyard Cottage—commonly referred to as a DADU (Detached Accessory Dwelling Unit)—is a small, fully independent residential structure located on the same lot as a primary home. Unlike attached units or basement conversions, these cottages are physically separate and offer complete privacy for residents. They are ideal for multigenerational households, long-term rentals, or extended guest stays. You can explore a range of real-world examples in our completed project gallery.
In the Seattle Municipal Code, these units are defined as “Accessory Dwelling Units, detached.” The city recognizes a variety of terms for them, including mother-in-law apartments, granny flats, backyard homes, and carriage houses. To understand how they fit within zoning guidelines and permit rules, refer to the Seattle Department of Construction & Inspections (SDCI) ADU resource page.
Most cottages include a living space, kitchen, sleeping area, and bathroom, along with a private, lockable entrance. In some cases, Seattle allows these structures to be located in side yards in addition to rear setbacks. For a breakdown of placement, height, and setbacks based on current rules, review our post on Seattle’s DADU permitting and zoning standards.
If you’re planning a new build, we recommend exploring our design-ready floorplans like the Anna for single-level living or the Diana for two-story flexibility. These layouts are crafted to meet local code while maximizing livable space and property value.
WHAT IS A BACKYARD COTTAGE?
In the Seattle Municipal Code, these units are defined as “Accessory Dwelling Units, detached.” The city recognizes a variety of terms for them, including mother-in-law apartments, granny flats, backyard homes, and carriage houses. To understand how they fit within zoning guidelines and permit rules, refer to the Seattle Department of Construction & Inspections (SDCI) ADU resource page.
Most cottages include a living space, kitchen, sleeping area, and bathroom, along with a private, lockable entrance. In some cases, Seattle allows these structures to be located in side yards in addition to rear setbacks. For a breakdown of placement, height, and setbacks based on current rules, review our post on Seattle’s DADU permitting and zoning standards.
If you’re planning a new build, we recommend exploring our design-ready floorplans like the Anna for single-level living or the Diana for two-story flexibility. These layouts are crafted to meet local code while maximizing livable space and property value.
REASONS TO BUILD A DADU
Detached backyard cottages offer a smart and flexible way to increase housing options without disrupting the look or feel of established neighborhoods. Because of their compact size, these structures blend seamlessly into single-family lots while providing fully independent living spaces. As a result, they offer a practical solution for homeowners who want to expand their property’s use without pursuing major redevelopment.
One of the most common reasons to build a detached unit is to create a long-term or short-term rental opportunity. A DADU allows property owners to generate passive income from unused yard space—often helping offset mortgage payments or long-term renovation goals. You can view real-world examples of income-producing builds in our project showcase.
In addition to rental flexibility, these units are especially valuable for families accommodating aging parents, college-age children, or multigenerational living arrangements. With Seattle’s population aging and housing costs rising, DADUs present a thoughtful way to keep families close while preserving independence. Learn more about how these benefits align with broader trends in our post on Seattle’s evolving residential landscape.
From a community standpoint, DADUs help diversify housing types in a way that’s quiet, sustainable, and compatible with neighborhood character. They offer new living options in walkable areas with existing infrastructure—without the environmental impact of large-scale development. Seattle’s 2025 rule updates make them even more accessible, as detailed in our latest guide on regulatory changes supporting detached housing.
Whether you’re interested in rental income, housing flexibility, or future resale value, a detached unit can help meet personal and community goals alike. To explore available floorplans, visit our collection of customizable designs.
Who Can Build DADU?
Prior to the December 2009 legislation, Backyard Cottages were permitted only in Southeast Seattle, where they were authorized by legislation in 2006.
BUILDING Requirements
You can build a Backyard Cottage if you meet the following requirements:
- You are a homeowner.
- Your property is located in a single-family residential zone (SF 5000, SF 7200 or SF 9600 zoned area).
- Your lot is not in a Shoreline District.
- Your lot is at least 4,000 square feet in area.
- You or your property co-owner(s) will occupy either the main house or the Backyard Cottage as a permanent and principal residence.
- You or your property co-owner(s) plan to live in the main home or the Backyard Cottage for more than six months of each calendar year.
- You or your property co-owner(s) who live on the property have a 50 percent or greater interest in the property.
Who Can Build DADU?
Prior to the December 2009 legislation, Backyard Cottages were permitted only in Southeast Seattle, where they were authorized by legislation in 2006.
BUILDING Requirements
You can build a Backyard Cottage if you meet the following requirements:
- You are a homeowner.
- Your property is located in a single-family residential zone (SF 5000, SF 7200 or SF 9600 zoned area).
- Your lot is not in a Shoreline District.
- Your lot is at least 4,000 square feet in area.
- You or your property co-owner(s) will occupy either the main house or the Backyard Cottage as a permanent and principal residence.
- You or your property co-owner(s) plan to live in the main home or the Backyard Cottage for more than six months of each calendar year.
- You or your property co-owner(s) who live on the property have a 50 percent or greater interest in the property.
Additional Considerations
If your property is large enough for a Backyard Cottage there are a variety of other issues you will need to think about. Consider the following:
- Even if your lot is 4,000 square feet or greater, do you have extra space to spare?
- How will your lot and neighborhood look with a Backyard Cottage?
- How can the design of the Backyard Cottage maintain your privacy and that of your neighbors?
- Will you rent the unit? Who is your potential renter and how can you build the unit to meet the demands of your rental market?
- Do you have time to care for an additional unit?
- Converting a detached garage might save money. Can you convert an existing detached garage into a Backyard Cottage?
- Besides exterior and interior work, are you prepared for the cost and disruption of extending the sewer, water, and electrical connections?
- Do you want to have separate utility meters?
- How will your tenants access the Backyard Cottage? Can you use a side yard or alley for this purpose?
- Will you need to hire professionals to help you design and build the Backyard Cottage?