What Is a Detached Accessory Dwelling Unit (DADU)?
A Detached Accessory Dwelling Unit (DADU) is a self-contained secondary residence located on a single-family property. These compact dwellings — sometimes referred to as granny flats, backyard cottages, or accessory dwelling units — include private entrances, full kitchens, bathrooms, and living spaces. DADUs can serve a range of purposes, from multigenerational living arrangements to rental income opportunities or more affordable housing options.
Greenpod Design is an ADU contractor based in Port Townsend, Washington, with over a decade of experience in small-footprint construction. Their work spans detached ADU building, Tiny Homes, and Modular construction, with a focus on energy efficiency and sustainable materials.
Greenpod's Approach to ADU Construction
Greenpod Design works to customize each accessory dwelling unit to suit the specific characteristics of a property. This includes considerations such as solar orientation, views, and topography. Their designs also incorporate Age-In-Place principles and full ADA compliance, making the spaces adaptable over time.
As an ADU builder, Greenpod uses SIP (Structural Insulated Panel) construction and sustainably sourced, non-toxic materials. This approach results in homes that are among the more energy-efficient options available — in many cases, the addition of solar panels would bring a Greenpod ADU to net-zero energy performance.
Their designs aim to balance spatial efficiency with livability, ensuring that even smaller floor plans feel functional and comfortable. Every aspect of the build is handled by Greenpod, simplifying the process for property owners.
ADU Rules and Regulations in Washington State
Building an ADU in Washington involves navigating local and state regulations. Here are some key points property owners should be aware of:
- HB 1337 (2023): Washington state law now requires jurisdictions within urban growth areas to allow up to two ADUs per lot, following each jurisdiction's next periodic update deadline.
- Types of ADUs: There are two primary categories — Attached ADUs (AADU) and Detached ADUs (DADU).
- Zoning: Up to two ADUs may be constructed in SF5000, SF7200, and SF9600 zones.
- Parking: Parking is no longer required for ADUs, though existing off-street parking spaces cannot be removed unless replaced elsewhere on the property.
- Owner occupancy: Property owners are not required to live on-site where an ADU is located.
- Size limits: In Seattle, a DADU is limited to 1,000 square feet of gross floor area in neighborhood residential zones, and 650 square feet in lowrise zones. State law allows ADUs up to 24 feet in height and 1,000 square feet in size.
- Minimum lot size: In Seattle, a minimum lot size of 3,200 square feet is required for a DADU in neighborhood residential zones.
Greenpod Design manages the full process for clients, from navigating permitting requirements to final construction. With their background as an experienced backyard cottage builder and granny flat builder, they are familiar with the regulatory landscape in Washington and work to make the process straightforward for property owners.
For those considering adding a DADU, in-law suite, or Casita to their property, Greenpod Design offers a practical combination of design expertise, sustainable building practices, and hands-on project management.