Comparative Analysis of Methods Detecting Plaster Integrity: A Study of Drayton Hall's Great Hall Ceiling

Abstract

While investigating the condition of one of our historic plaster ceilings, Drayton Hall Preservation Trust (DHPT) staff identified a widespread need for guidance and clarity regarding available and applicable nondestructive testing (NDT) methods and risk assessment matrices for historic plaster ceilings well beyond the boundaries of our own property. Despite DHPT’s ready access to engineers, architects, and conservators, we have struggled for years to determine the most appropriate methodology for documenting and assessing the Great Hall plaster ceiling. Measurements of structural deformation in the floor system above this ceiling correlate closely with observable cracks on the plaster, but the degree to which these cracks are propagating through the plaster layers —if at all—is proving far more difficult to establish. Other hidden conditions include the potential for delamination of plaster layers, the performance of several modern conservation materials, and the integrity of extant historic fasteners in the system. While the problems posed by the unique confluence of conditions that threaten this ceiling are unique to DHPT, the need for guidance and clarity in the assessment of historic plaster ceilings is far more common. With our partners at the Clemson Master’s in Historic Preservation Program (MSHP), the Warren Lasch Conservation Center (WLCC), and Bennett Preservation Engineering, we will conduct and publish a review of current literature on this topic, evaluate the accessibility, viability, and applicability of NDT methods, and create a matrix to aid building managers and homeowners in their efforts to evaluate their own plaster ceilings in a proactive manner.