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Limb: Rethinking Heavy Timber Joinery through Analysis of Tree Crotches

Limb: Rethinking Heavy Timber Joinery through Analysis of Tree Crotches

LIMB reconsiders historic heavy timber construction across cultures to develop new joinery methods by focusing on the natural occurrence of branch bifurcation in different wood species. Because of its low value, often the crotch of a tree is not harvested for commercial purposes. This project uses this vital element to design connections that replace traditional mortise and tenon or steel connections.

By replacing the joint with a single piece of wood that purposely grew for bifurcation in nature, and by moving the structural connection away from where vertical and horizontal members come together, a stronger construction joint can be achieved. In the 17th century tree crotches were harvested for a variety of purposes from bracket systems in barn structures to structural joints in the construction of naval vessels (Encyclopédie Méthodique: Marine). In the 1960’s renown modern furniture designers such as Sam Maloof replaced two part mortise and tenon joints in their chairs with a singular bifurcated piece increasing connection strength and producing more sinuous form. More recently Whole Trees Architecture and Architectural Association program directors Martin Self and Emmanuel Vercruysse explored organic form aggregation using entire tree branches with bifurcations.

Our research sets itself apart by assuming a syntactical approach to design. We are not interested in unique form generation based on unique parts, something that is very well explored in the realm of digital fabrication, rather are constructing a reusable language of bifurcated joinery. There are a number of common natural angular occurrences in limb bifurcations and we have reduced those to a set of parts that can be “tuned” to develop diverse structural systems. The two types of crotches identified are: the “r” and “y” type. We have designed a digital fabrication workflow that extracts standardized milled parts from an inventory of salvaged material. The cataloguing of recurring angles and other physical properties inherent to different species of trees allows for further development of the structural possibilities of this system, which can be applied to nearly any type of tree bifurcation allowing for infinite combinations within the language of bifurcated timber joinery.

Project Team:

Steven Mankouche
Kasey Vliet
Peter von Buelow
Bob Allsop
Kevin Bukowski
Cody Gilman
Shaobo Niu
Omid Oliyan Torghabehi
Andrew Thompson
Benjamin Wichman