RBA’s Huestis Hall Basement Expansion and Renovation project at the University of Oregon “topped out” recently with the completion of the at-grade exit stair enclosure for a portion of the underground science complex.
The renovation itself is a complete overhaul of the basement research facilities within the boundary of the original Huestis Hall footprint. The program also now pushes beyond that original boundary by having captured over 3000sf of additional area for the project excavated out of bedrock earlier this year at the south edge of the site. About 90% of the project is underground and it’s being run in several phases each with its own major structural component making “topping out” (the traditional celebration of the completion of the last major piece of structure) a bit anticlimactic. So the general contractor, Lewis Crutcher Lewis (LCL), decided instead to celebrate the success of its subcontractors after the completion of the most visible portion of the structure and program: the new exit stair enclosure at the edge of the Science Green.
Although admittedly not the most important program element of the project, the stair addresses major issues with the previous basement egress. And the completion of the stair enclosure represents quite an achievement for the contractors. The enclosure was designed to have a minimal presence at the edge of the Science Green to satisfy campus open-space goals. The transparency of the enclosure is due primarily to the use of single, butt-glazed, ultra-clear glass. Looking straight through the enclosure there is no perceptible tint or color to the glass. The single-glazed all-glass enclosure meant however that the stair would need to be unconditioned. To reduce the chance for temperature spikes a custom ventilation detail at the storefront head and sill was employed to allow the enclosure the ability to breathe. The transparency of the enclosure is coupled with an unbelievably thin structure. The flat roof is a ½” sheet of steel welded in sequence such that the force embedded in the welds helps to counteract the plate’s deflection. The steel sheet sits on a shallow perimeter beam held aloft by six round cantilevered columns. A myriad of subcontractors came together to successfully coordinate the fabrication of these custom details. It’s a credit to LCL and their subs that it was so well executed.
At a recent RBA staff tour of the project, we got to see the enclosure close up as well as explore the rest of the project. The extensive phasing of the project is to allow the continued operation of the existing core facilities at the heart of the project site. These operations will sequentially shift outwards in future phases as the contractor play musical chairs around ongoing activities. The phasing complexity was very evident in the basement where portions of the project are ready for occupancy and others starkly reflect the makeshift appearance of temporary systems. All phases of the project are expected to be complete by March 2013.