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Exterior Limestone Conservation

Riverside Church

The church was conceived by industrialist, financier, and philanthropist John D. Rockefeller Jr. (1874–1960), and minister Harry Emerson Fosdick (1878–1969), as a large, interdenominational church in a neighborhood important to the city, open to all who profess faith in Christ. It is famous for its large size and elaborate Neo-Gothic architecture as well as its history of social justice. In 2012 it was listed on the National Register of Historic Places.


New York, New York

Architect & Date

Allen & Collens, 1926-30


Beyer Blinder Belle Architects

Services Provided

ICR developed a conservation program to address the issues of the limestone decay at the tower:

  • Preliminary conditions survey

  • Design & execution of laboratory & in-situ testing programs

  • Identification & definition of methods of treatment for cracking, loss and disaggregation

  • Development of consolidation and repair methods

ICR was tasked with diagnosing the cause of cracking, disaggregation and loss of the statuary and other carved gothic elements on the Indiana Limestone façade of the Church. The work involved a preliminary conditions survey and extensive laboratory work to identify the mechanisms causing decay. The decay appeared to manifest in similar conditions across all elements resulting in cracks, disaggregation and loss.

Laboratory work included visual microscopic analysis, micro-chemical spot testing, petrographic analysis, Fourier transform infrared spectroscopy, gas chromatography mass spectroscopy, anion analysis, X-Ray diffraction analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Proposed consolidation treatments were pre-tested in the ICR laboratory for acid resistance and strength increases before site testing. Site tests were evaluated for depth of penetration and hydrophobicity. 

The severity of decay and the potential loss in some of the protruding architectural elements posing a possible public threat could not be treated with consolidation alone. ICR had to determine what conditions would be appropriate for consolidation alone and what severe conditions would require removal of decayed material, followed by tooling to sound material, and subsequent consolidation. Due to the great height in many of the decaying elements, the removal of decayed material does not alter the tower's appearance and replacement materials did not have to be introduced.