Defect Investigation

Investigating Extreme Salt Decay to the Portland-Purbeck Spiral Stair

Our work continues investigating and monitoring extreme salt related decay to a Portland-Purbeck limestone spiral stair in an early eighteenth century church tower.   The stair has seen approximately 30mm of stone loss over approximately 20 years, caused by exposure to marine salts and significant change in the internal environment within the tower.  Monitoring work continues so that we can understand the point when decay has reached a new equilibrium so that conservation, repair and partial replacement can proceed.  Decay on this scale is highly unusual and presents unique conservation challenges!