Who checks tank waterproofing on a Berbera build?

A tank waterproofing supervision gap is where a coat, lap or penetration gets covered before anyone with authority inspects it, so stored water leakage only shows after handover. When a joint, penetration or membrane lap is covered without inspection, it becomes a likely leak path, and the defect surfaces once the tank is backfilled, tiled or in use.

Where does the tank waterproofing supervision gap open?

It opens between the trades, when the applicator finishes a coat and the next trade covers it before anyone with authority looks. Cement-based coatings and liquid membranes cure fast, so the window to inspect a coat or a lap can be hours, not days. The general mechanism is that a coat applied too thin, a lap left short, or a corner radius left square all pass unnoticed because the next layer hides them. Supervision has to be present at that moment, not told about it later. Confirm the exposure conditions and the product's suitability, including the specified thickness of each coat, with the project's specification or engineer.

What does weak supervision actually miss?

It misses the part of the work that cannot be seen once the tank is backfilled, tiled or filled. Typical missed items are lap lengths on sheet or liquid membranes, the seal around inlet, outlet and overflow pipes, the fillet at the wall-floor junction, and the surface preparation that the first coat needs to bond. Each one is a path for water. The durability of embedded reinforcement depends on the membrane remaining intact, so ask the project's engineer to confirm what protection the specification calls for. Even a correctly specified system fails if the substrate was dusty, damp or smooth when the first coat went on. The leak then appears as damp patches on the outside face, a dropping tank level, or staining at the base. A supervisor can only catch these by watching the preparation and the first coat, measuring wet-film thickness as general practice, and confirming the specified dry-film thickness against the project's specification or engineer.

How can a client or supervisor detect it?

Detect it with records and a physical walk before the tank is closed up. Before work starts, ask for the inspection and test plan and confirm that waterproofing has a hold point, which means no covering until someone signs. During the work, ask the applicator to record each coat, its product batch and its thickness, and photograph the corners and pipe penetrations. After curing, follow the project's specification or engineer for a flood test, and record the water level over a set period. If the tank is already buried and leaking, a careful internal inspection with the tank empty can show lap failures, blisters and open joints. Confirm the acceptance criteria with the project's engineer rather than assuming a duration.

What to do next

On any water-retaining structure, add a single hold point to the inspection and test plan: no backfill, screed or tiling until the waterproofing is witnessed, photographed and signed by the client's representative. Walk that tank before the coat goes on and again after curing, and keep the record with the handover file.