Rain Penetration Problems Associated with Retro‐fitted Cavity Insulation Available to Purchase

Surveyors, who may be involved in specifying retro‐fitted cavity insulation, need to know the key factors which influence the potential risk of rain penetration. Proposes guidance for surveyors to undertake a low‐cost initial visual survey and desk study as a first stage in the assessment of a dwelling′s suitability for retro‐fitted cavity insulation. A case‐study of low‐rise housing on a local authority estate on the south coast of England, which has retro‐fitted cavity insulation,allowed the identification of these key factors and testing of their statistical significance. Factors identified are aspect towards prevailing wind and driving rain index; exposure (related to local topographic and sheltering features); wall impermeability; and any factors of particular significance to the site. If an individual dwelling has a combination of these factors, it is likely to have a 60 per cent increased risk of rain penetration.