Photo Essay: Enchanting Tree Houses

"This was really a parameter-driven project," explains Lukasz Kos, a Toronto-based designer and cofounder of the architecture firm Testroom. "That is, I had to let the trees decide how the tree house would be."

At the base of the tree, a staircase rolls on casters upon two stone slabs, allowing occupants to enter and exit regardless of how much the tree house may be swaying or rocking in the wind. Solid plywood walls punctuated by a floor of red

PVC constitute the "opaque" base story, which is largely protected from the outside elements. "The idea was to have the tree house open up as it gained elevation," explains Kos. The second story is surrounded by a vertical lattice frame, allowing for breezes, air, and light to filter softly through walls while still establishing a visual perimeter between outside and inside space. At top, the tree house is completely penned in, a suspended patio with a ceiling of sky.