Installing Insulating Glass In Existing Wooden Sash Incorporating the Historic Glass

The Delaware Building was constructed shortly after the Chicago Fire of 1871 using pre-cast concrete panels on the outside. Originally six stories in height, the Italianate-style office building received an additional two floors around 1890 that were faced with sheet metal to resemble the appearance of the facade below. The lower two floors were originally dressed with ornamental cast iron arches. Later removed, they have been recently restored. Individually listed on the National Register of Historic Places, the building has an impressive interior atrium that survives, providing light to offices on the upper floors. The windows are set in a deep reveal, paired in an alternating pattern of wide and narrow bays. The wooden sash are double hung and most have arched tops. The window openings are richly detailed with keystones, flanking columns and heavy surrounds, and are separated in pairs on most floors by various pilaster treatments. As part of the rehabilitation of the building in 1982, the existing wooden windows were repaired, weatherstripped and retrofitted with an additional sheet of glazing using a technique that permitted creation of sealed insulating units in each sash.