The rust-colored streaks and spiderweb cracks on the exterior of the Federal Detention Center near Seattle were more than just a cosmetic problem. After almost 25 years in the region’s notoriously rainy climate, the eight-story facility was deteriorating: The exterior’s pre-cast concrete panels had cracked and spalled on all sides of the structure, allowing water to penetrate and corrode the internal structural rebar. It was a dangerous situation that was quickly getting worse.
When Precision was awarded the $450,000 spalling repair project, some panels had a crumbling façade and exposed rebar ends that could allow chunks of concrete to fall off and plunge eight stories to the ground. A site walk in 2021 uncovered additional locations to those identified in the original statement of work, likely proof that the building was further deteriorating and in need of immediate repair.
A total of 25 spalling and three cracking repair locations were identified, with most requiring roof-mounted, swing stage scaffolding for work access. The swing stages were connected to the eighth-story roof via davit arms, while the swing stages themselves were craned onto the low roofs directly below the work area. The multiple crane lifts and stage locations had to be tightly coordinated to both minimize disruption to the facility and to efficiently allow concrete-patch cure times. The lower roofs were protected by plywood to prevent any damage, and the swing stages were connected to the davit arms on the top roof.
Repairs to the precast concrete panels included: Removing deteriorated and unsound concrete from damaged locations; saw-cutting to a quarter-inch-minimum depth around the periphery; cleaning the concrete and applying corrosion inhibitor at the exposed steel reinforcing; applying repair mortar, two coats of rust inhibitor, and a fresh coat of exterior-grade paint; and removing all existing patches and disbanded concrete. The project was completed in summer 2021.