Samsun Piazza Shopping Centre — Waterproofing at Pipe Penetrations

A leak in a shopping centre is not only a building problem; a closed shop or wetted stock is a direct commercial loss. Waterproofing work therefore has to be quick and conclusive.

On this stage at Samsun Piazza the work was not about broad surfaces but about penetrations. Every drainage and service pipe piercing the slab leaves a void between its sleeve and the concrete; almost the whole of the waterproofing is either solved in those voids or not solved at all.

A leak does not come from the open surface

In waterproofing, failure is almost never in the middle of the coating; it shows up at the details.

• Pipe penetrations — the void between sleeve and concrete is the point most often missed.
• Flanged coupling zones — beneath the fitting is where the membrane loses continuity.
• Wall-to-slab junctions — the lap is left short where the membrane turns up the vertical.
• Around gullies and outlets — where the membrane is not clamped to the flange, water gets underneath.

The sequence at a penetration

The area around the pipe is first cleaned mechanically and loose concrete removed. The void between sleeve and pipe is filled with a sealing compound, dressed to a fillet, and finally the surrounding slab is coated with a liquid-applied membrane so the detail is tied into the surface. Skip that last step and the filler stands alone — it separates at its edge with the first thermal movement.