Loblolly House

Loblolly House

This was the most exceptional project submitted for the BIM Awards this year, judging by the fact that it won the BIM Award citations for both of the categories in which it was submitted: Creating Stellar Architecture Using BIM, which recognizes outstanding quality of architectural design achieved through the use of BIM; and Outstanding Design for Fabrication Using BIM, which looks at how BIM enabled fabrication rules and techniques to be incorporated into the design. The jury was unanimous in the agreement that the Loblolly House deserved the award for both categories, even though it was a highly unusual decision. To put it simply, none of the other entries in these two categories came close to the standards demonstrated by the Loblolly House project. Once the jury deliberations were completed and the winning firms' identities were disclosed, it didn't come as a huge surprise to find that the Loblolly House was a project by the firm, KieranTimberlake Associates, famous for their work on prefabrication that is captured in their seminal book, "Refabricating Architecture." Some of the firm's preliminary explorations with using BIM for more efficient and effective modular design and offsite fabrication processes were described in this AECbytes article published in February 2006: BIM Symposium at the University of Minnesota. Evidently, the firm has come a long way since then in its use of BIM.

The Loblolly House, completed in 2006, is a single family residence of 1,800 SF located on Taylors Island, Maryland. It was named after the tall pine trees that characterize its site on the Chesapeake Bay, and the design concept was focused on fusing the natural elements surrounding it to its architectural form. The house is composed entirely of off-site fabricated elements and ready-made components, assembled from the platform up in less than six weeks. An aluminum scaffold system provides both the structural frame and the means to connect other elements and components to it with the sole aid of a wrench. The idea was to enable not just swift assembly at the site, but also speedy and whole disassembly in the future, allowing the parts of the building to be relocated and reassembled in new ways instead of being wasted. Figure 1 shows some exterior and interior views of the project after completion. The exposed scaffold detail can be seen in the top right image.

Larger image

Figure 1. Some views of the completed Loblolly House project. (© Barry Halkin, KieranTimberlake Associates)

A desire to better understand the building and its elements led to the application of BIM as a tool for the design, development, fabrication, and assembly of the Loblolly House. Each component was modeled to accurately illustrate its building materials and finishes, and this information was subsequently used by the contractor to precisely fabricate the parts in the shop. As a means to improve the fabrication method, the model was incorporated with additional parameters dictated by manufacturing limitations and other restrictions. It was the BIM methodology that made the simultaneous off-site fabrication of this project possible. Without the geometric and dimensional certainty afforded by the closure of the parametric model, parts could not have been assembled in advance to the required tolerances. In addition to the benefits of designing in 3D, BIM enabled more efficient structural and mechanical coordination, better management of parts and schedules for procurement, a clearer approach to assembly sequencing, as well as a way to control fabrication and decrease assembly and construction tolerances. Virtual construction of the model allowed the team to refine the design prior to its assembly on site and detect and resolve conflicts before they they caused delays, wasted resources, and increased cost. The virtual model became the sole source of information from which all details, schedules, part lists, and fabrication drawings were derived and it was used to collaborate with the fabricators and engineers instead of drawings. Figure 2 shows some views of the BIM model of the Loblolly House.

Larger image

Figure 2. The top image shows the full 3D view of the Loblolly House BIM model, while the lower images show an exterior stair detail and a connector detail. (© KieranTimberlake Associates)

Some more specific examples of the design and construction of the Loblolly House using BIM are captured in the following sequence of images. Figure 3 shows how the model was used as a tool to help design the cedar rain screen panels that form the facade. The pattern of the rain screen was actually composed over a photograph of the forest, and the wall panels were then developed and refined within the virtual model. Figure 4 shows the components of the structural aluminum frame created with embedded data such as manufacturer and distributor information, model name, size of profile, length, and cost. Since these components were first assembled virtually in the model, the project team was able to accurately catalog sizes and quantities and submit an order via e-mail using the list derived from the model. As the model developed and the number of components increased, the challenges of assembly and sequencing become more apparent. The BIM model was used to develop a sequencing schedule, shown in Figure 5, which clearly defined the assembly strategies for each day, reducing wasted time and avoiding possible conflicts.

Larger image

Figure 3. The wall panels developed and refined within the virtual model. The lower sequence of images shows the same panels fabricated off-site being delivered and installed on the site. (© Barry Halkin, KieranTimberlake Associates)

Larger image

Figure 4. The model of the structural aluminum frame, showing details of the frame and connectors as well as the data embedded within a component. The lower images show the aluminum components being fabricated at a factory and subsequently assembled on site. (© Barry Halkin, KieranTimberlake Associates)

Figure 5. The sequencing schedule for the onsite assembly of the Loblolly House. (© KieranTimberlake Associates)

Peter Aaron/Esto

The outer layer on the façade of the Loblolly House is a bifold polycarbonate hangar door that doubles as a sunshade when locked in the open position. The translucent polycarbonate has many of the same thermal properties as glass, but it weighs less and keeps out the glare of direct sunlight.