Pete recently did an interview on BBC Radio 4 - You and Yours - which investigated a case history of failed cavity wall insulation.
Thermal Imaging is a technique relatively new to the building trade, and unheard of in the timber and damp industry. We have pioneered the use of thermal mapping to highlight areas of thermal differences which encourage condensation. Our building surveys are starting to include this sort of imagery to demonstrate how differences in temperature can encourage dampness in old buildings. Cold walls are often damp, and conduct heat much more readily than dry walls. Imaging can show how badly installed insulation causes cold spots, which encourage mould and mildew. We often find cold spots in walls that indicate leaking pipes from radiators, water supplies and such. Thermal imaging is very useful to map timber frames - we have found hidden timber frames where none were thought to exist. Our thermal imaging cameras can also help show that 'rising damp' diagnosis is wrongly and fraudulently peddled to clients, by showing that these areas of walls are actually quite warm, and not wet - but contain salts, which show as dark spots on walls.
We combine thermal imaging with other instrumentation - we frequently undertake Carbide Tests as well - these measure the Total Moisture Content of a sample drilled from a wall - and can show that where a 'timber and damp' salesman has told you rising damp exists, that in fact the wall is quite dry. We also use thermo hygrometers, and other equipment which together can give a complete picture of the reasons for, and quantity of damp that may or may not exist. Almost always, the damp companies are totally wrong, and fraudulently so, in their so called diagnosis.