The roof over the Alaska Center for the Performing Arts had been plagued with leaks since its construction. The embossed metal shakes used to cover the roof were not appropriate for the Anchorage climate. Compounding the problem, phenolic foam insulation was used to insulate the roof. In the presence of water, the foam becomes corrosive. The roof deck was supported (off the structural concrete roof deck) with light-gauge metal joists, which were corroding away due to the water in the phenolic insulation.
The team of EEIS Consulting Engineers, Inc. (EEIS) and Kumin Associates was charged with designing a new roof system and preparing the structural calculations and the working drawings for repair of the roof. Because of budget constraints, only the south face of the roof could be repaired during Phase I. A vapor retarder, metal joists, rigid insulation, stainless steel metal roof panels, and snow guards were installed. The parapets at the base of the roof slope were armored; the gutters and valleys were reconstructed and reflashed; and new glycol heat trace was installed. EEIS and Kumin Associates designed the repair of the remaining portions of the roof in Phase II 3 years later. EEIS conducted site investigations, prepared the structural calculations and roof details, and worked with Kumin Associates to develop working drawings and construction documents for the repair.
EEIS designed a new roof system to replace the existing roof system, which was leaking. The new design was lighter than the original system. Existing skylights were eliminated, which solved many problems with the existing roof. The project included designing a storage area for equipment used on the roof for snow removal. EEIS also prepared a formal snow removal program to keep snow loads on the roof at acceptable levels and restore the building to compliance with life safety code. The facility remained operational and impact on patients was minimal during the reroofing.
EEIS provided architectural/life safety design, structural engineering, and construction support for a retrofit of the Nome City Hall roof. The existing roof was leaking and had condensation problems at the eaves. The existing metal roof was replaced with a new standing metal roof and new flashings. Retrofit of the 41- by 82 foot roof area included a utility tether, vent penetrations, and tie downs for boiler flue support and existing braces.
EEIS assessed a roof damaged by snow overload, made measurements, and produced drawings for repair. An unusually heavy snowfall had resulted in drifting where the building roof changed elevation. A heavy snowdrift caused the roof purlins to fail over an area of about 1,600 square feet and also caused damage to the supporting frames. The damaged purlins and support frames were replaced over a 3,200-square-foot area. The metal roof deck and the replaced purlins were upgraded to comply with the current International Building Code (IBC).
Several additions had been made to the Romig/West school over the years, and the roofing systems for the additions were in fair to poor condition. The goal of the project was to remove the existing systems and replace them with a new roof system that was better insulated and easier to maintain. EEIS reviewed record drawings and conducted on-site surveys of existing roofs to confirm “as-built” conditions. EEIS developed a report on roof condition with recommendations for replacement and then designed new roofs for the buildings. Deliverables included design drawings and as-built drawings at the conclusion of the project.
The Unalaska High School building roof was leaking. The building also needed interior remodeling. The school was a prefabricated steel building with interior wood partitions and several additions. EEIS provided structural engineering design for the remodel and consulted to determine the cause of the leaks. EEIS located the cause of the leaks and provided details to correct the problems. The roof had not been designed for the snow loads of 100 to 150 pounds per square foot that it was experiencing. EEIS designed details to strengthen the existing roof structure. One challenge overcome by EEIS was having to redesign some connections after demolition exposed conditions that were different from those on the as-built drawings. EEIS also provided construction-support services.
Leaks from the roof had been reported at isolated areas during periods of high wind and rain. EEIS investigated the issues and the condition of the existing roof and provided options for repair or replacement of the damaged areas. Existing roof materials, assemblies, and code issues were addressed, and recommendations were presented to the owner .
EEIS evaluated the flat membrane covered portion of the gymnasium (10,980 square feet) and high school (37,360 square feet) roofs and made recommendations for new roof systems to eliminate the drainage and leak problems with those roofs. The recommendations included adding roof drains and installing tapered insulation. The evaluation included a schematic-level cost estimate for the new roof system.
A four-story building originally constructed as condominiums or apartments had been converted into a halfway facility that housed several hundred people. The population overloaded the existing ventilation systems and caused high levels of humidity in the facility. In the winter, moisture in the air condensed and froze in the roof cavity. During warm spells in the winter, the ice melted and caused massive leaks into the building, sometimes resulting in collapse of the ceilings. Building deficiencies included many improperly sealed penetrations from the building interior into the attic and roof cavity ventilation insufficient to vent the humid air that leaked into it. EEIS evaluated the roof and designed improvements, including adding ventilation for the roof cavity, sealing the roof cavity from the upper floors, and installing new more powerful exhaust fans for the kitchens and baths.
Working for the contractor, EEIS provided layout/life safety design and structural engineering to vent the existing roof and install a new roof system. This fast-track project required great attention to detail and overall logistical planning. EEIS began design in July 1989 and obtained a Certificate of Occupancy for the facility during the first part of January 1990. EEIS also handled the application for the building permit.
EEIS provided drawings and specifications to convert a failing unvented "hot" roof system to a vented roof system. The existing plywood roof deck and fiberglass batt insulation were removed. Damaged decayed roof rafters were replaced. The cavity between the rafters was filled with sprayed-in-place insulation, which left 2 inches of space above the insulation to vent the roof. New plywood deck, ice and water shield, and asphalt shingles completed the repairs to the roof.