20 k demographic
rural studio roundwood team
Project Type: Residential
Client: 20k demographic
Design group: Rural Studio Thesis/ Outreach Team "Roundwood"
Location: North Ward Street Greensboro, AL
The Rural Studio is a unique design build program based in the heart of west-central Alabama. The ongoing mission of the Rural Studio is to allow students to work within the context of the local culture and community in order to create pragmatic yet inspired architectural solutions. This philosophy advances the idea that students are able to improve themselves as well as their community through hard work, involvement, and an intimate connection to the people and places for which they design.
The 2007/2008 Thesis year at Rural Studio was charged with designing the “20K House”. This project is based on a government loan known as the Section 502 Mutual Self-Help Housing loan. This is a subsidized loan created to help those with extremely low incomes to reach the goal of home ownership.$20,000 dollars is the smallest loan amount provided through the 502 government program. Therefore the goal of the 20K house is to build a home for approximately $10,000 in materials and $10,000 in labor. This home provides the owner with an alternative to the prevalent trailer, which depreciates over time and leaves the client in a downward spiral of debt and destitution. The 20K house aspires to be warm, dry, safe, and hopefully a beautiful home for all those who qualify for the loan.
In addition to the 20K project, one team of four individuals was offered the opportunity to build with “Roundwood”. Roundwood is simply small diameter timber that has been cut by the local forestry department in order to create more space and encourage a healthier ecosystem within the forest. These timbers have a minimal monetary value and are often left on the forest floor to decay. The Rural Studio alongside the rural sociology department at Auburn University has received a 3-yeargrant in order to study the possible application of this material within rural communities. The goal set forth by our year was to use the timbers in their most raw form. This means the timbers would be used round and green without the aid of wood-misers or drying kilns. The roundwood house is the result of research and experimentation paralleled with the goal of creating an in expensive yet noble home.
Research and experimentation was the first step in finding an application for these small diameter timbers. Initially, several ideas were explored through mock-ups and trial procedures including bending, connecting, and protecting the wood. Several bending tests quickly demonstrated that loblolly pine, the primary species of wood used, was unstable and unpredictable. Structural applications for small bent pieces of wood seemed unlikely due its tendency to break without warning and a small bending radius. Further research proved that the wood was most structurally stable when used in tension and compression. Protecting the wood from exposure to the elements and drying-in the house was another primary concern that was addressed through experimentation. Some of the early tests included using laths with plaster, cob, and a concrete/mud mixture. Although the cob and concrete mixture showed promise, it was decided that plastering over the structure could be problematic due the tendency of the wood to shrink and twist.
Because research dictated the best use for the wood was in tension and compression, exploring the truss as a possibility for structural purposes became the next logical step. Several iterations were explored with a few variables in mind. The form should allow for the most efficient floor plan. The structural logic of the form should be paralleled with a strong spatial logic. The house should touch the ground in as few places as possible. And the form of the structure should allow for application of a protective skin.
debarking & treating
In order to ready the wood for construction, it went through several steps of preparation. The first and most arduous task was the debarking of the wood. This process involves thin draw blades that peeled the bark away from the timber. The next step was a light chemical treatment involving a boron based solution that protected the wood from fungal and insect attacks. This solution, known as BoraCare, was ideal treatment as it was an easy and nontoxic application process. Alternative treatment methods involved harsh chemicals and specialized knowledge and equipment. In preparation, long shallow trench was dug and lined with plastic sheeting. The Bora Care solution was diluted with water and poured in to a standard garden sprayer. As the Roundwood was sprayed the excess BoraCare would gather in the bottom of the ditch and soak further into the wood. The timbers were then stacked under a shed and left to air dry. After the Bora Care dried the wood could be sanded. Finally, holes were drilled through the log so that dowel-nut connections could be inserted.
Initially, it was decided flitch plates would be used to connect the different members of the truss. Unfortunately, one of the many properties of this species of the wood is its tendency to shrink and twist as it dries. Because we received the material straight from the forest, it would take several years for the wood to completely dry. Flitch plates would be ineffective due to the shrinking and twisting effect. With the help of Mark Knabe, a member of the USDA Forest Service, a simple connection was developed that would allow the wood to twist and shrink while remaining stable and structural. The connection consists of a standard ¼”thick steel pipe cut into 10” lengths. A dowel-nut connection previously inserted into the logs are then inserted into what has been coined the “Knabe connection” and tightened with a nut and washer. Further development allowed the connection to be used for a multitude of purposes. It became the structural connector for the truss as well as a way to support the roof and floor system. Steel plates welded inside the pipe provide attachment points for the roof and wall panels. These panels provide a protective and isolative barrier.
wall panel construction
After experimentation with primitive mud, cob, and plastering techniques proved unsuitable, it was decided that thin panels made out of standard building materials would act as the skin of the house. Because the Roundwood provides the structure of the house, the panels would need minimal support. The wall panels consisted of 2x4slaid in a 4ft. x 4ft. grid. Each panel was 8ft wide. A ½” layer of plywood would then be painted and applied to the 2x4s. This plywood layer stabilized the panels as they were moved into place and acted as the interior finish. Constructing the panels with the interior finish pre-applied avoided difficult finish work around the truss. Also, instead of butting the plywood sheets directly against one another, a ¼” reveal was left. This reveal reduced time spent on finish work and provided an interesting compositional element. The panels were then lifted into place and bolted to ¼” steel plates that protrude from the Knabe connections. Attaching the panels directly to the steel connections kept the skin separate from the Roundwood, thereby allowing the wood to twist and shrink without directly affecting the walls of the house. After the wall and roof panels were bolted into place, standard batt insulation was inserted followed by a radiant/vapor barrier. Combining the batt insulation and the radiant barrier increased the R value of these thin walls to R-27. Batons placed on top of the radiant barrier provided a necessary air gap between the barrier and the corrugated metal.