THE KASUBA METHOD
The Kasuba Method of building curvilinear architectural walls links two up-to-date unrelated approaches: it uses the design principles inherent to tensile fabric structures and combines them with standard building materials. The method was successfully employed in two prototype structures, a guesthouse studio and kitchen.
The method differs from conventional approaches in that it bypasses the following practices: 1. Fabrication of disposable molds for casting reinforced concrete shells. 2. Fabrication of shaped metal or wooden ribs or grids onto which a skin of a material is affixed. 3. The use of computer design methods that replicate a sculpted curvature or simulate tensile surface configurations.
The Kasuba Method eliminates the above preliminary procedures at a considerable saving of expense by using a flexible membrane-in-tension as a guide upon which a durable hard surface is built up.This then is The Method.
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The step-by-step procedure, used in both prototype buildings, was as follows:
After the foundations were cast, the back wall of the kitchen and the arched wooden frames (drawing #1) were anchored to the foundations. Strips of a wire mesh 48" wide were then stretched between the frames (drawing #2). Tension, introduced by stretching the strips, transformed layers of the inert mesh into a tensile membrane, while tension flows between the edges of frames articulated the configuration of the membrane's surface. To control the thickness of spray-foam, units of pleated mesh were laid on top of the membrane and connected to it with hog-rings used in the upholstery business; a layer of felt-lined expanded metal lath, attached to the underside of the membrane, stopped the foam from seeping through. A local company sprayed the polyurethane foam, and as the foam hardened, the layers blended forming a solid shell. The whole exterior was then covered with expanded metal lath and stuccoed with fiberglass reinforced concrete, then waterproofed with two coats of 100% acrylic coating and clad with aluminum plates. The interior was plastered and painted. The shell is approximately 7 inches thick (drawing #3), with an energy conserving value of R-27.
The documentation of the whole procedure can be seen on /ShellDwellings.htm in New Mexico.
Because a membrane in tension finds equilibrium within itself, the resulting shell is structurally self-balancing, which accounts for its unique aesthetic as well. Depending on environmental conditions or scale-related requirements, the strength of such a shell can be increased by adding thickness to layers, by upgrading the materials, and/or by cables or rebars laid over the membrane.
The International Residential Code 2003, Section R104.11, based on the use of alternate materials, design and methods, provides a framework for obtaining a building permit.
November 2005, New Mexico
