A visual assessment of the flat roof areas at HMP Pentonville in London produced inconclusive results as to the full extent of their condition. There was physical evidence of water ingress within the building structure but identifying the exact location and levels of moisture was not possible as water was tracking through the system. As a result, it was not clear what remedial action: repair, removal or overlay, and which waterproofing system was best suited to reinstate the roof’s integrity...