Patch repair (drain)

A patch repair is a short cured-in-place liner, typically 500mm to 1,000mm long, installed inside a host pipe to seal cracks, open joints or small root entry points without excavation. The patch consists of a glass fibre or felt mat impregnated with epoxy or silicate resin, positioned on a packer or inflatable bladder and pushed to the defect under CCTV guidance. Once inflated, the resin cures against the pipe wall over 30 minutes to four hours depending on ambient or hot water cure. Patch repairs are appropriate for isolated defects in otherwise sound drains, often used on London terraces where full excavation would damage paving or block paving. They will not address widespread structural failure, in which case full-length lining or replacement is required.