Stabilizing Deteriorating Plaster

Once the cause and extent of damage have been determined, treatments such as shoring, stabilization, and limited demolition can begin, preparatory to repairing or restoring historic ornamental plaster.

First, roof or plumbing leaks must be repaired to eliminate the problem of water intrusion. General structural repairs should be undertaken to arrest building movement, which weakens the base coat plasters to which the ornamental enrichments are attached. Ornamental plaster deflection should be corrected by shoring from below followed by re-anchoring.

Testing for poor adhesion of base coat to lath or ornament to base coat, should be conducted to reduce further loss of enrichment. Adaptive use intrusions should be carefully removed to protect the existing decorative plasterwork.

Code-required fire suppression systems should be evaluated at this time. Modern building codes may require heat/smoke/flame detectors and automatic sprinkler systems of various types and applications. Fire suppression systems as well as all mechanical systems (HVAC, plumbing and electrical) systems should be designed so that they accomplish their purpose with minimal impact on the decorative plaster.

Plumbing for an automatic sprinkler system, for example, can be run above new and existing coffering so that the sprinkler heads barely protrude from the rosette centers in the coffered design. Access should be provided for future system maintenance or repair.