Otterbein Calcea Insulating Plaster supplied by Stoneware Studios being applied by the men of Kenneth Sisk Plastering in Cork City. Easy to apply, no biodegradation, NHL with perlite (natural forming volcanic glass used for a long time for drainage and aeration) and with v good thermal performance we like this product. Thermal conductivity 0.083 W/(m-k) giving a uvalue on an un-rendered 500mm stone wall of 0.84694 W/m2K for 50mm thick or 0.5705 W/m2K for 100mm thick which is up there with the best.