Location: New York, NY
Architect Cass Gilbert designed for Frank W. Woolworth and his company the world’s tallest office building (794 feet) in a free Gothic style. The building, completed in 1913, has an innovative steel frame and is clad with some 400,000 square feet of white and polychrome terra cotta.
Almost immediately after the completion of the building, signs of stress and breakage were observed in the exterior terra cotta cladding. Constructed without relieving angles and movement joints, the lack of expansion combined with the irreversible moisture expansion, typically experienced by the new terra cotta, caused the severe build-up of internal stress and caused extensive vertical cracking.
The restoration of the exterior commenced with the development of stress relieving techniques. Every second horizontal joint along the entire width of the building was cut to the full depth of the terra cotta (approximately four inches) allowing the stress to dissipate. Broken and cracked blocks were replaced with cast stone, joints were repainted and surfaces repaired.