08-20-07 Agenda Item 2A, City Hall Repair Update

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WJE ENGINEERS ARCH ITEeTS MATERIALS SCIENTISTS Arden Hills City Hall Building City Council Wark Session on 20 August 2007 14 August 2007 Page 3 4. Painted steel masonry relieving angles were installed on the exterior walls instead of the specified hot-dipped galvanized steel angles. The original design did not specify flashing or weep ropes at the relieving angles; however, through-wall flashing and weep ropes were installed at the relieving angles. This membrane through-wall flashing terminates approximately Y. inch from the outer toe of the relieving angle and approximately 2 inches from the exterior face of the wall. With the flashing terminating within the wall, water is not permitted to completely exit the wall system and therefore the flashing is ineffective. In addition, by terminating the flashing within the wall, the painted steel angles are exposed to moisture. Recently created inspection openings revealed significant corrosion occurring at the ends of the angles. 5. The as-built construction of the stone coping varied from the shop drawings prepared by Mankato Kasota Stone, Inc. and the design drawings in several ways: a. An overhang with drip edge was not provided on the backside of the coping stones as shown on both the design and shop drawings. The absence of an overhang with drip edge would permit water to run across the face of the sealant and result in reduced sealant life. b. The specified anchors used to secure the stone to the underlying parapet wall do not appear to be installed. c. There is visible evidence of unaccomodated movement (i.e., separations and bowing) at one location due to the apparent absence of expansion joints, in combination with inadequate anchorage of the coping stones. REPAIR Refer to the attached table that presents repair alternatives and costs.