Build-over and extension surveys in Great Sankey

Build-over and extension surveys — how it works here

If an extension sits over or within three metres of a public sewer, United Utilities must agree to it under a build-over agreement, and Building Control will want evidence of the run's position and condition. That evidence is a survey, and it is cheap before the plans are fixed and expensive afterwards. The retrospective version of this job is the more common one in west Warrington. Westbrook, Callands and Old Hall have had thirty-five years of conservatories, garden rooms, wider driveways and rear extensions built over drainage that was laid at sensible depth under lawns. The pattern is consistent enough to predict: the drain behaves for two decades, an extension goes on, and within a year or two it starts backing up because the run was never properly bridged or diverted. The camera shows the deformation and exactly where it sits relative to the new structure, which decides whether it can be lined from inside or has to be dug.

• Position, depth and condition established before plans are finalised
• Report in the format United Utilities and Building Control ask for
• Retrospective surveys where an extension has already gone over a run
• Shows whether a crushed section can be lined in situ or must be excavated
• The single most avoidable fault we find in Westbrook and Callands