2| P a g executive Summary Introduction and approach to the study UCL and BRE have investigated the effectiveness of waterproofing treatments to reduce rain penetration in unprotected masonry cavity walls on behalf of the Department for Business, Energy & Industrial Strategy (BEIS). The aim was to establish whether the use of such treatments could safely allow wall cavities to be insulated as a retrofit measure in exposed areas, where such insulation was otherwise deemed unsuitable due to the increased risk of moisture ingress. A key feature of this study has been to acknowledge and investigate the implications of contextual factors that give rise to ‘As-Built, In Service’ (ABIS) conditions, as distinct from the ‘As Designed Theoretical’ (ADT) condition of walls. ABIS is defined as the physical state of real exposed walls of residential buildings at any given point in time post-construction, subjected to the environmental conditions found in-situ and to their ageing, and has been a consideration for the assessment of waterproofing treatments during this work, Click here for MORE