• Square Footage
  • Location
    Seattle, WA
  • Contractor
    Francis Build
  • Structural Engineer
    Todd Perbix
  • Photography
    Mark Woods Philip Newton
  • Press

Originally deemed an “un-buildable” steep slope lot, Treehouse was built with naïve optimism and determination to defy the odds.

Utilizing modest materials and an economical building approach, the result is an inventive home that lives amongst the trees in Seattle’s Central District.

Read More


In 1999, the owners discovered an “un-buildable” steep slope lot while searching the internet for cheap land in Seattle. At first attracted by the price, the owners quickly realized that the lot was adjacent to the park where their community p-patch was located. With a favorable soils report, understanding neighbors and naïve optimism, the vacant land seemed too good to pass up. The “Treehouse” was completed in 2009.


The primary design objectives were three: 1) respond to and resolve site access and topography challenges to make the “un-buildable” lot buildable; 2) design a house that captured the qualities of living in the trees: framed views of the forest, filtered light from above, protected as in a bird nest; 3) design a cost effective and resource efficient green building.


Site challenges were the source of fundamental design solutions. The auger-cast pile and steel frame foundation system grew out of the necessity of using a crane to reach the site. The radius of the crane determined the extent of foundations, generated the form of the steel trusses, and ultimately preserved the existing topography.

Space defines the experience of living in the trees. The design investigates how enclosure opens to / retreats from the forest. A central skylight is a hearth that brings light into the building and anchors overlapping volumes that frame views of forest and sky.

The project was realized with a “materials in the room” mindset, with the hope of making good space economically and improving a small corner of the world.


  • Small size – utilizing a compact 24’ x 30’, the house maximizes light and space rather than expensive materials and detailing
  • SIPS panels and BIBS insulation create an efficient envelope
  • Heat Recovery Ventilator (HRV)
  • Passive cooling via stack effect at operable skylight
  • Water conserving fixtures
  • Future PV/Solar thermal capability