Whole tree architecture and design mostly uses trees that are not directly in demand for industrial processing, (diseased, fallen, invasive, wind-bent, young growth) and create amazing structures and objects with them.
Building with whole timber, as opposed to milling it down into ‘products’ has lots of advantages, ranging from increased fire resistance (seems paradoxical but true), low embodied energy and carbon sequestration. Whole Tree Architecture is headed by forester-architect Roald Gundersen, who has made a career out of working with these whole trees that are pruned as part of better forest management.
This farmhouse in Avalanche, Wisconsin, was built almost entirely from trees taken from within 500 yards of the house. The house features a slab on grade foundation with in-floor heating tubes to take advantage of the solar gain in the winter from its large southern exposure.The envelope is straw bale, but the structure is entirely “whole tree” with branching columns supporting it and framed with round wood poles under the second floor and roof. The attached solar greenhouse on the south side of the house adds heat in the winter and serves as a gray water recycling system to treat water from the kitchen and shower.
Aside from the marvelous eco-aesthetic of whole-tree homes, time, energy and money are saved by skipping the normal steps of processing raw wood into standard wooden structural sizes. Also, less carbon is released into the air and the naturally curved wood branches are stronger than their straight-and-narrow counterparts.
The process behind Whole Tree Architecture’s beautiful designs start with a walk in the forest with a building design in mind. The trees are individually selected for harvest. The trees selected are 10 inches or less in diameter and Often are chosen right on the owner’s site. The trees are peeled (debarked) and cured as they stand:
Each tree is chosen both for its structural and design integrity, and for the effect that its removal will have on the forest left standing around it. Often the selection will be based as much on thinning an overcrowded stand or managing an invasive species as it will on that tree being the nearest with a 10 inch diameter trunk.
Instead of clear-cutting this method allows for pick and choose. When the tree has been chosen the bark is peeled from it while it stands in the forest (allowing the waste products to go back to the forest floor). Then the tree is left to cure standing for several months, during which time it will loose up to 50 percent of its weight in water, making it easier and safer to move it out of the forest when it is needed for construction.
Whole trees selected in this way have a similar weight to strength ratio in compression and twice the strength of steel in tension. Whole trees are stronger than milled lumber because milling violates a tree’s concentric, continuous and spiraling fibers removing the strongest outer layers of the tree, which are naturally pre-tensioned to resist wind shear. Whole timber supports 50 percent more weight than than the largest piece of lumber milled from the same tree.
Besides the structural strength of these components, the integrity and form of the whole trees lends an organic and harmonious aesthetic that cannot be achieved with conventional materials.