Chicago Water Tower
The original timber roof structure for the Chicago Water Tower and Pumping Station was destroyed in the Great Chicago Fire of 1871. After the fire, a new roof system consisting of cinder concrete fill on corrugated iron panels supported by iron trusses was erected on the existing pumping station as one of the city’s first fire-resistant roofs. After many years of successful service, the original slate roofing was due for replacement. CTLGroup was commissioned to perform a comprehensive investigation to assess the current overall condition and structural integrity of the roof structure, as well as the durability potential of the existing structure to provide for an additional 50- to 60-year service life.
Results of CTLGroup’s work revealed that the condition of the corrugated roof deck was highly variable, and that approximately 40% of the exposed deck exhibited moderate to severe levels of deterioration. In addition, removal of masonry encasements around selected trussbearing areas revealed the presence of significant corrosion in some areas. The extensive corrosion of the roof deck had compromised the load-carrying capacity of the roof system. Recommendations were provided for rehabilitation/replacement.