Treatment of rising damp and salt decay: the historic masonry buildings of Adelaide, South Australia

Abstract

The City of Adelaide suffers from rapid damage to historic building materials due to salts, rising damp, and damp-proof course failures. Adelaide City Council has partially funded repairs to over 400 buildings in the past 15 years. To begin to examine the scope of this problem and the effectiveness of various treatments, 24 historic buildings in Adelaide were examined, with a focus on the building materials, historic interventions and current treatments applied to treat rising damp and salt decay. Analysis of 90 samples found high levels of sodium sulfate, sodium chloride and sodium nitrate in cellars, ground water and building materials, suggesting a clear example of rising damp. Samples of disintegrating masonry, depth profiles acquired by drilling, poultices and damp proof courses (DPC) were analyzed by Ion Chromatography (IC) and Environmental Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (ESEM/EDS). Mercury Intrusion Porosimetry (MIP) and capillarity test were carried out in the building materials and DPCs showing that porous materials with high porosity, small pores and low strength are more prone to salt weathering. The City of Adelaide is a natural laboratory for comparing and analyzing different treatments of salt-laden masonry, with hundreds of treated buildings of the same age, in the same environment, and with similar building materials.