Abstract

Plaster (often lime plaster, reinforced with animal hair) installed on wood lath secured to wood framing was a common ceiling system for hundreds of years in the Americas, and for thousands of years in Europe. Despite having a relatively good record of stability, some ceilings of this type have collapsed. Given their overhead position, often above large groups of people, when cracks or localized areas of displacement or damage occur in these ceilings, the question often arises as to whether the ceiling is stable and safe. Because procedures for stability assessment of historic plaster ceilings on wood lath are not well quantified in building codes or technical literature, this article proposes key considerations and best practices for assessing these ceilings.