Refurbishing solid walls with externally or internally applied insulation can help to reduce heat loss from a building, but it has the potential to introduce a range of undesirable effects such as condensation and mould growth if not carried out correctly. This guide for surveyors, designers and installers provides advice on assessing the potential risks and reducing the likelihood of long-term problems. It discusses:
· surveying and assessment of exposure risk and existing ventilation,
· detailed design,
· quality assurance on site,
· an integrated approach by surveyors, designers and installers.

The guide will also be useful to clients and householders in creating realistic expectations as they commission an appropriate team of professionals to undertake an installation.