Will the surveyor need to drill into walls or cause damage whilst performing a damp or mould survey?

In most cases, no. Damp and mould surveys are designed to be non-invasive. Surveyors will inspect visually, use handheld instruments and tools, and sometimes collect air or surface samples. Only if there’s strong evidence of hidden damp or mould that can’t be confirmed otherwise would they recommend more intrusive methods, such as drilling small test holes. If that’s needed, they’ll always explain it first and keep disruption to a minimum. The goal is to diagnose without causing unnecessary damage.