The industry is going through a huge change in respect of envelope testing, with thermal imaging as the new kid on the block. I wish to warn your readers not to be too enthusiastic in using its practitioners.

Thermal imaging hit the Far East several years ago. Every mother’s son and uncle was a qualified thermographers, even without construction qualifications.

The country in question no longer relies on this form of investigation as it lost confidence in its ability and the practitioners.

The same is happening in the UK. For the price of a second-hand car, anyone can buy a camera and set themself up as a thermographic surveyor. Armed with a smattering of construction knowledge they baffle clients with pretty pictures. After handing over a big cheque the client proceeds to spend a fortune on remedial work – some of which is not necessary.

Before you employ a thermal imaging expert, make sure they hold a recognised academic qualification. Do they carry professional indemnity insurance? Are they members of a professional body? If you do not get a tick in those boxes you get what you deserve – a chancer and a big bill.

Rod Appleyard, forensic building defects surveyor and expert witness