Based on the differential survey conducted, the roof sag as measured from the edge of the roof to the center was between approximately 17 ft. 4 in. and 17 ft. 8 in. The range is given since the exact thickness of the roof foam at these locations is not known. This measured value was compared to computed values from analysis under dead load only since at the time of the measurements there were no superimposed live loads.
Impact-echo testing revealed that the precast concrete panels were solid with no signs of corrosion – related deterioration. Infrared thermography indicated that the concrete deck surface was being adequately protected from moisture by the roofing.