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January 2017 construction update

With 2016 in the rearview, we’re gearing up for a busy 2017. You won’t be able to miss the work being done on the building’s exterior as crews remove brick and limestone for repair and to address the steel underneath. Inside, you can peek through a new viewing window on the mezzanine level that looks into portions of the Cincinnati History Museum and Museum of Natural History & Science. Follow along as crews begin transforming the space into a new lobby, classrooms and exhibit galleries. Here’s a look at what else you can expect this month.

Upcoming Work

  1. As the windows on the face of Union Terminal continue to be removed for cleaning and repairs, the aluminum frames around them are being cleaned using dry ice. Pellets of dry ice are blasted at the metal but leave no residue because they sublimate (change state from solid to a gas) almost immediately.
  2. The disassembly of the north drum wall (the wall just below the half dome in the rear of the building) begins this month. The drum wall consists of an exterior brick face with a terracotta tile backup wall and steel frame behind it. This construction methodology has resulted in poor thermal expansion capabilities of the wall, leaving little cushion as brick and steel expand and contract from the region’s fluctuation in temperatures and humidity. This has resulted in movement of the brick and steel away from each other, causing damage to the wall system. This wall protects the interior Rotunda ceiling, one of the most memorable features of the building.
  3. The fountain and plaza area is critical to the historic fabric of the building and will also undergo much-needed repairs. Surveyors are completing a full documentation of the fountain and plaza area, photographing and measuring the location of every single stone in preparation for its disassembly. In the coming months, the fountain and plaza will be disassembled and rebuilt in a precise manner once the areas below (which forms the roof for portions of the lower level) are waterproofed to prevent future water damage.
  4. Masons are using hand tools to continue applying mortar to limestone joints across the front of Union Terminal. Using acid digestion analysis on samples of the building’s original mortar, historic preservation architects were able to better understand the mix of sand and limestone that formed its basis. Using that scientific analysis, preservation architects and masons tried several ratios to find the proper match, finally settling on 1 part Portland cement, 1 ½ parts limestone aggregate and 7 parts sand. That mortar is now being applied 1 to 2 inches deep into over 35,000 feet of limestone joints.
  5. An outdated boiler and two chillers, each over 25 years old, were recently removed from the mechanical room to make room for updated mechanical systems. The mechanical room will be overhauled and the two remaining boilers will be removed in the coming months. New boilers and chillers will be more efficient, increasing overall environmental control inside the building.

Number to know: 1270 – There are 1,270 windows of the front face of Union Terminal, each of which will be removed and thoroughly cleaned. While the windows are removed, painted plywood will temporarily take their place and the historic metal frames will be repaired.

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