PARADISE INN RENOVATIONMount Rainier National Park

PROJECT OVERVIEWOWNER: National Park ServiceLOCATION: Mount Rainier National Park, WACOMPLETED: April 2008SIZE: 42,000 square feet ARCHITECT: FFA Architecture

Received a 2010 Grand Award for Engineering Excellence from the American Council Of Engineering Companies Of Oregon

The renovation of the 42,000 square-foot Paradise Inn set a new precedent in structural engineering for extreme snow loads while carefully preserving the historic character of this revered cultural resource. The 121-guestroom inn perches among the clouds at the 5,400-foot elevation on Mount Rainier. Here, the annual average snowfall is 53 feet, and the area set a record for the most snowfall ever measured in the United States during the winter of 1971/72 with 93.5 feet. Design snow loads for this project exceeded 600 pounds per square foot. Recurring harsh winter conditions and the glaciating action from the snow field directly uphill from the inn had pushed this national public treasure toward collapse.

The log trusses in the Great Hall of inn’s lobby wing had deflected up to 9 inches out-of-plumb, and the crushing effect of drifting snow deflected the entire east wing out-of-plumb by as much as 8 inches. Preserving Paradise Inn’s historic qualities inspired an innovative approach that stabilized the building with post-tensioned concrete shear walls that were cleverly concealed within the existing stone

chimneys. Now completely covered by the original basalt stones, these structural cores support the historic masonry and serve as the primary lateral force resisting elements for the lobby and dining wings. In addition, the inn’s entire 3-story east wing was lifted from its rubble foundation, lowered back onto new concrete footings, and then pulled back nearly 8 inches into an upright condition.

Once the inn was closed for rehabilitation, the removal of architectural finishes exposed a myriad of unanticipated structural defects including extensive rot in the historic log trusses and numerous failed structural members resulting from the massive snow loads. Innovative solutions were devised at every turn to restore structural integrity while meeting the National Park Service’s meticulous requirements to retain the inn’s original character. Set in a magnificent locale that attracts two million visitors per year, Paradise Inn stands as an engineering prototype for extreme snow loads and creative structural solutions that will allow the public to enjoy the building’s historic charm for another century.

Paradise Inn

INNOVATIVE DESIGN

Determined to preserve this National Historic Landmark, the design team reinforced the 42,000-square-foot heavy timber frame structure to resist snow loads in excess of 600 pounds per square foot. Innovative solutions included reconstructing the three historic stone masonry chimneys around post tensioned concrete cores to act as bracing elements; restoring the Alaskan Yellow Cedar log trusses and columns that had been compromised by rot; and straightening the entire east wing which had deflected 8 inches out-of-plumb from lateral snow pressures.

Post-tensioned concrete chimney cores and shear walls were added to provide stability to the historic masonry chimneys and serve as the primary lateral force resisting elements for the lobby and dining wings. Each basalt stone was meticulously photographed and labeled during the chimneys’ deconstruction and returned to its exact position during reassembly, completely concealing the new state-of-the-art structural core. The new post-tensioned chimney systems, reinforced roof diaphragms, and cleverly concealed

drag elements at the ridge line and at roof transitions allowed the removal of four very intrusive concrete shear walls that were added in the Great Hall of the lobby wing during a previous 1980’s retrofit. The removal of these walls restored the historic integrity and original charm of the inn’s Great Hall.

During construction, extensive rot was discovered in many of the architecturally exposed Alaskan Yellow Cedar logs that comprised the lobby and dining room trusses and columns. Most of the original columns were founded on large basalt stones and had deteriorated significantly at their bearing locations. The rustic log framing of the inn helps to define the visitor experience at Paradise and, as such, retaining these elements was a top priority from a historic preservation standpoint. KPFF worked hand-in-hand with the architect and National Park Service to create a number of custom epoxy repairs for these members and specified treatments that preserved these key elements in-place.

The east wing had deflected out-of-plumb as much as 8 inches to the north and many localized areas of the wing were on the verge of collapse. Straightening the east wing required the positioning of four temporary 70-foot long steel wide-flange beams lengthwise under the basement level floor framing. These beams were supported on timber crib piles spaced at approximately 8 feet on center. Shoring lines were added over the top of these beams between each floor level, continuous to the top floor framing. Once these elements were in place, the east wing was raised clear of its rubble foundation by incrementally jacking the wide flange beams up off the crib piles. New foundations were poured, and the east wing was lowered, leveled and reconnected to its new foundation.

To pull the structure plumb, cross cabling was installed at each level above the basement at approximately 8 feet on center along the length of the building, and all existing shear walls were removed. The cables were then tensioned in sequence from one end of the building to the other and the building was allowed to creep slightly over the course of several days. As the cables began to relax, they were re-tensioned, repeating the process for many cycles lasting several weeks.

Although the visual impact of this procedure would have required time lapse photography to fully appreciate, at times the audio was truly remarkable. The structure creaked and groaned under the tension of the cables with the occasional unannounced “POP” that would take everyone by surprise. Ultimately, the upper levels of the east wing were pulled approximately 8 inches to the south, into vertical alignment with the lower levels. Once upright, the east wing received new wood shear walls and floor diaphragms to ensure its correct upright posture for years to come.

HISTORIC SENSITIVITY

Paradise Inn stands today as a structural engineering marvel. It is a testament to how creative design solutions can be integrated into an existing structural system in a historically sensitive manner; even when faced with the brutal climatic conditions and extreme loading criteria that are inherent with a location on the upper slopes of Mount Rainier.

Preserving the lodge’s historic qualities required new ways of thinking about structural solutions. In fact, standard practices during a renovation 20 years prior added four visually obtrusive concrete shear walls in the Great Hall of the lobby wing which significantly altered this open space and detracted from the building’s historic character. This project showcases multiple unique and inventive strategies for engineers to adopt and adapt as they seek to invisibly brace or repair historic structures or support any building that must withstand extreme snow loads. The engineers’ use of post-tensioned concrete cores in the chimneys as the primary lateral force resisting elements and the state-

of-the-art treatment that brought the east wing back into alignment are engineering coups. The complex process of restoring dry-rot damaged and structurally compromised but historically important log trusses viable load-carrying elements also advances engineering practices.

Thanks to public media, there is a recent resurgence of interest in our national parks. Mt. Rainier National Park is distinguished as North America’s fifth oldest national park. Because of the inn’s vast popularity, the public will immediately recognize that critical behind-the-scenes changes have taken place. Shear walls no longer obstruct the view across the Great Hall. The wood floors are now level, and the east wing stands straight. These improvements send a clear message that the building is safer. Because the structural elements supporting these changes are invisible and only enhance the building and its historic qualities, Paradise Inn is a powerful public testament to engineering excellence.

Photo by Jeremy Bitterman

THE STRUCTURAL TEAM

A proactive approach and willingness to achieve the client’s vision are what make Adam such a valuable team member. He has worked with a wide range of building types for new and renovated structures. He draws upon this project diversity and his versatility to produce new concepts that inform the design. He is responsible for structural analysis and design, detailing, production and construction services. He assists the structural principal-in-charge with project schedules and budgets, reviews testing and quality control reports for compliance, performs site visits, and reviews all preliminary drawings. Since coming to KPFF in 2001, Adam has found a sense of reward in coming up with a great idea and working with the project team to turn it into reality.

Adam Nawrot, PE, SEStructural Engineer

As founding principal of the KPFF Portland office, Art has over 35 years of professional engineering experience in the analysis and design of complex structural framing systems. His willingness to tackle any issue on a project has honed his problem-solving abilities beyond the realm of structural components. Art’s portfolio highlights his initiative to work out the finer details and retain architectural aesthetics in a safe and purposeful manner. He enjoys working on projects that are meaningful to the community. As structural principal, he excels participating in the evaluation of existing structures and the selection of the structural systems. Art will also provide internal peer review of documents at key milestones.

Art Johnson, PE, SEPrincipal | Structural Engineer