SIP Small Cottage Seattle WA

Location: Seattle, WA

Project Information

Project Type: Residential, Tiny House < 900 sq. ft.
Manufacturer: Premier Building Systems
Builder: TC Legend Homes
Design Professional: TC Legend Homes
Year Built: 2015


High Performance: No
HERS/EUI Index Score: 63
ACH50 - Blower Test Results:
CO2 lbs./sq.ft./year:

Awards/Certifications: DOE Zero Energy Ready Home, ENERGY STAR Certified, EPA Indoor AirPLUS

“We chose structural insulated panels (SIPs) for their excellent insulation values, airtightness, and ease of construction.”

Wanting to downsize, the owner of a large home in Seattle’s Sand Point neighborhood contacted TC Legend Homes about building a small cottage above her garage. Owner's plan was to move into a new detached accessory dwelling unit (DADU, as they are called in Seattle) and rent the larger home.

Owner was originally looking for an architect to draw up plans, but TC Legend Homes was able to handle the design work in house, saving money. In the process, we were able to save the original garage, reinforcing it and using it as a base for the cozy backyard cottage above.

The resulting structure combines old and new and beautifully captures the industrial aesthetic that owner wanted. Carefully finished dimensional fir lumber creates an inviting interior space, while also helping to cut costs. Our crew used exterior-grade fiber-cement siding panels for the tub surround, a method that not only saves money but creates a durable, waterproof surface reminiscent of stone or poured concrete. Small balconies open the living room up to the outdoors and give the elevated, energy-efficient home an almost a tree-house feel.


  • High-performance insulation system for enhanced quiet and confort
  • Comprehensive draft protection
  • Fresh air system for cleaner indoor air
  • High-efficiency comfort system
  • Energy-efficient appliances and advanced lighting technology for energy and water savings

“The owner … contacted us about building a small cottage above her garage. For the walls and roof … we chose structural insulated panels (SIPs) for their excellent insulation values, airtightness, and ease of construction. These locally made panels come precisely cut, allowing for fast construction, a strong, airtight shell, and practically zero jobsite waste.”

– Ted Clifton, builder, TC Legend Homes

DOE Link to this project: SIP Small Cottage Seattle WA

To explore other Zero Energy Ready Homes, visit the Department of Energy’s Tour of Zero page.

Affiliated Members

BASF Corporation

Houston, TX
Premier SIPS

Puyallup, WA


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