Will a mould survey show hidden mould such as behind walls?

A good mould and damp survey can detect hidden mould indirectly. While surveyors won’t usually tear down walls during a routine inspection, they use tools like moisture meters, thermal imaging, or air sampling to spot problem areas. If hidden mould is suspected behind plaster or in cavities, the survey report will recommend targeted investigations, which may involve opening up small sections or taking samples. The aim is always to balance accuracy with minimal disruption. In short, yes — a mould survey can reveal if hidden growth is likely, even if it’s not immediately visible.