Roof reconstruction helps stop leaks
A recent retrofit of World War II-era warehouses has created an economic asset for Port of Pasco, Wash. Completed last November, the project will boost employment and generate lease revenue for the city.
The warehouses are located in a 600-acre area known as Big Pasco Industrial Center (BPIC). They were built in 1942 as an inland staging center for lend-lease shipments to Russia during the war, and they were transferred to city ownership in 1959 by the U.S. General Services Administration.
When they originated, the wood buildings were classified as “temporary structures” but have withstood many decades beyond their war mission. However, much of the space in the warehouses had been unmarketable to manufacturing tenants in recent years because of obsolete features and chronic roof leaks. “The roofs just leaked and leaked and leaked,” says Jeff Bishop, director of properties and development for the city. “We kept losing tenants.” The buildings also had outdated lighting, electrical and fire protection systems.
Recurring leaks were attributed to the flat roofs that prevented proper drainage and aggravated the deterioration brought on by the passage of time, deferred maintenance and exposure to the elements. Repeated asphalt repairs also were placing too much stress on the buildings’ trusses. “Flat roofs just don’t work in this climate,” Bishop explains.
In 1996, the city hired local architecture and engineering firm MacTec-Meier Associates to investigate the possibility of salvaging and retrofitting the buildings. An economic analysis concluded that the cost to retrofit the space to code would run about half the amount of replacement construction.
The city decided to upgrade nine 43,000-square-foot bay sections. The necessary improvements included installing a 400-watt metal halide lighting system and 600-AMP electrical service; improving sprinklers; modifying firewalls; replacing the original flat, built-up roofs with standing seam metal roofs; and achieving compliance with Factory Mutual standards (building codes specific to industrial facilities).
Garco Construction, Spokane, Wash., served as the general contractor and completed construction after about a year of work, Bishop says. The old roof, underlying wood deck and purlins were stripped away to expose the 8-foot-deep, built-up wood trusses that made up the primary framing. The damaged bays received steel splices before being fitted along the top chords with steel saddles at 6-foot intervals.
A custom metal rafter system was then bolted to the saddles to create a support grid for the purlins and 24-gauge, preformed roof panels (from Butler Roof Division, Kansas City, Mo.). The new pitched roof system’s fastening clips are seamed into the panel joints, allowing the roof to accommodate thermal expansion and contraction.
The $4 million project was underwritten in part by a $2.8 million grant from the Economic Development Administration within the U.S. Department of Commerce. The grant was issued because the renovated space is expected to create 180 to 215 jobs; each tenant has 30 to 40 employees on site. At projected lease rates, the remaining cost of the retrofit project should be reco vered within 10 years, Bishop says. In addition, the salvage effort has qualified the warehouses for placement on the National Register of Historic Places.
