Seattle’s First Net Carbon DADU

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What do you do when you need more space in your home but are reluctant to leave your neighborhood? This was the central question for the clients of our Net Carbon DADU project. They had outgrown their existing home, a modest 100 year old craftsman bungalow and worried that they would need to leave their well-loved neighborhood to find a home big enough for their increasing needs for space.

Living Shelter Architects explored the possibilities for our client to comfortably stay in their home. After going through several conventional design iterations for how to expand their space including an attic renovation and addition, we decided to explore a DADU concept as a possible way for them to add space and more fully embrace what their property had to offer.

What is a DADU?

DADU stands for detached accessory dwelling unit and is often referred to as a backyard cottage. Whereas an ADU (accessory dwelling unit) is located inside or attached to a single-family home, a DADU is a secondary unit on a single-family lot that is detached from the main residence.

Seattle’s First Net Carbon DADU

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To maximize their small lot, we designed a DADU that connected the main level of their existing home, across a deck, to the main level of the new cottage, where we programed flex space that includes a small kitchen. Down a flight of stairs from there, we set a guest bedroom/workshop and full bath below grade.

All of this design was layered with deep sustainability through a close collaboration between Living Shelter and the contractor, Mighty House Construction. From the foundation, insulation, and waterproofing, to the floors, paints, and roof, nearly everything in this DADU was chosen because of its low environmental impact and high performance.

Another consultant on the project, Lucas Johnson of 475 High Performance Building Supply, estimates that this is, “Seattle’s first carbon-negative DADU.” We are hopeful, and we will discover for sure after one year of occupancy, whether or not we achieved the goal to be carbon-neutral.

This experience exemplifies what a good architectural project can have: great communication and collaborative design, flexible and creative clients, and highly skilled builders. We hope the DADU adds another 100 years to the life of this home.

Our net carbon DADU has received some fantastic attention lately. In October 2018, this project was selected for the Green Building Slam presentations. And in April 2018, the DADU was one of our projects on the The Northwest Green Home Tour.