Build-overs missed

Existing public sewers not identified at design stage, then discovered at excavation. Cue retrospective agreement and design changes.

Manholes inside the new room

Sometimes unavoidable, often badly handled. Double-sealed covers and access need to be designed in, not bolted on at finishes stage.

Surface water connections

New roof areas plumbed into the foul system 'because it was closer'. The Regulations require separation where infrastructure allows.

Drains under floors

Concrete poured before drainage details are agreed. Future maintenance becomes very expensive.