Client Wold Architects Building The MNDOT building is a twelve-story, state government building in downtown St. Paul. The building's facade is mainly composed of alternating horizontal bands of strip windows and granite panels. Curtain walls are located at two areas of the building. Scope of Service Encompass was retained to perform an exterior building facade investigation and analysis. The purpose of the investigation was to identify the sources of moisture intrusion occurring in numerous locations at the facade, primarily at the building's curtain walls, and to evaluate several spalls and cracks in the granite panels. Encompass performed on-site facade inspections utilizing a 120-foot high lift and swing stage. Description Based on the inspections and a review of the original design drawings, the source of moisture intrusion at the curtain wall was located at the un-sealed expansion joint of the vertical mullion covers. The cracks and spalls within the granite panels was determined to be due to a lack of space between the top of the panels and the bottom of the continuous shelf angles above. Basically, severe corrosion of the shelf angle would displace a panel upward into the shelf angle above, creating large compressive stresses within the panel. In addition to the cracks and spalls, the upward movement of the panel resulted in a loss of a crucial horizontal restraint located on the bottom of the panel. Lacking this restraint, the primary restraint keeping the panel in place was friction between the corroded shelf angle and the bottom of the panel. This elicited concerns of a panel eventually falling from the building. Encompass created the repair details for the restoration of the facade, which consist of removing all panels, restoring or replacing the shelf angles, and re-installing adequate flashing and the existing panels. The facade remediation was completed in 2009 with an approximated cost of $6 million. Encompass partnered with Wold to serve as the owner's representative and performed daily on-site observation services. |
