Hot-melt sealant is a bitumen or coal tar based jointing compound applied at high temperature to seal manhole cover frames, chamber rings and gully surrounds against water ingress. The material flows when molten and cures to a tough, waterproof bond as it cools, providing a flexible seal that accommodates minor movement. UK installations follow BS EN 14188 and Highways England Manual of Contract Documents for Highway Works. Hot-melt is identifiable on inspection by its glossy black appearance at joint lines and chamber surrounds. The product is typically applied by specialist drainage contractors using purpose-built melting kettles, with careful temperature control to avoid degrading the binder. While robust, hot-melt sealants can crack over decades of thermal cycling and traffic loading, leading to surface water infiltration into the chamber, particularly at busy junctions across central London.
Hot-melt sealant
Bitumen-based jointing compound applied molten to seal manhole covers and chamber rings.
