Cast Architecture: ADU and Backyard Cottage Design in Seattle
Cast Architecture has been involved in the accessory dwelling unit (ADU) space in Seattle since the city first considered backyard cottages citywide in 2009. As advocates for abundant and affordable housing choices, they have built up considerable experience in designing detached ADUs (DADUs), tiny homes, small houses, and studios across the region.
Their work as an accessory dwelling unit builder is grounded in a broader perspective on housing policy. They view modest infill housing — such as backyard cottages and DADUs — as a practical strategy to address the housing crisis, climate change, and inequities in access to housing opportunities. In their view, more efficient land use is essential, and ADUs represent a meaningful way for individual property owners to contribute new housing while building generational wealth.
Pre-Approved DADU Designs
One of Cast Architecture's notable contributions to the backyard cottage builder space is their Cedar Cottage design. This design is one of seven cottage designs pre-approved by the City of Seattle, and it also carries pre-approval from the City of Kirkland. Pre-approved plans can simplify and speed up the permitting process for homeowners looking to add a detached ADU to their property.
To date, Cast Architecture has designed over 80 ADUs and small homes. Among these projects are:
- Widner Cottage — winner of the AIA Seattle Home of the Month and recognized as Best Small House by Fine Homebuilding magazine
- Lichtenstein Studio — recipient of the Reader's Choice Award from Fine Homebuilding magazine
- Cedar Cottage — awarded the AIA Seattle Home of Distinction in 2022
A Focus on Practical, Infill Housing Solutions
Cast Architecture's approach to ADU design reflects a commitment to making housing options accessible to as many people as possible. Their portfolio spans a range of small-scale residential projects, including granny flats, studios, and detached backyard cottages — all designed with an eye toward livability and efficient use of space.
For homeowners in the Seattle area considering adding an accessory dwelling unit to their property, Cast Architecture offers design experience backed by years of advocacy and a track record of recognized projects. Further details about their backyard cottage designs can be found at castcottages.com.
