The inspecting Architect had identified spalling of the stone in the tower and spire, and SJ&P were engaged to advise. A detailed inspection was carried out, and while a large part of the stone itself is durable, there were large areas or quantities of in-built ironwork cramps and tie bars within the masonry. Corrosion of these and the consequent expansion was causing spalling. Our research showed that the top of the spire had been rebuilt in 1940, but using Portland cement mortars, hard, brittle and difficult to dismantle. Detailed consideration was given whether tie bars could be removed, and how to counteract the circumferential forces from the spire.
Work was carried out by specialist contractors according to detailed designs prepared, cutting out the defective stonework, removing the corroding ironwork and, where essential, replacing existing totally decayed ironwork with stainless steel links. On completion the building in this case is repaired with the matching stonework of the same kind without any apparent modern intervention, the stainless steel completely concealed.
Georgian Group Architectural Awards 2009
St Lawrence, Mereworth – Restoration of a Georgian Church