Two Water Tanks — PVC Membrane Tanking

Before — bare concrete tank structure

The object

A residential apartment building in Merrylands, near Parramatta, with two concrete water tanks that required full internal waterproofing: a fire-services (fire water) tank and a stormwater retention tank.

The problem we solved

Both tanks had to hold water reliably over the long term. Tanks are one of the most demanding waterproofing applications — the membrane is permanently immersed, every seam is under constant hydrostatic load, and any defect shows up immediately on the water test.

Our scope of works

Full internal tanking of both tanks with a 2 mm Soprema PVC sheet membrane, hot-air welded on site: walls, floors, internal corners, penetrations and terminations. Tank 1 (fire water) — 280 m²; Tank 2 (stormwater) — 240 m². Total 520 m² of installed membrane.

Special features / difficulty

Confined-space work with fully welded seams throughout — in a tank there are no low-risk zones, every metre of seam must be watertight. Corners, penetrations and terminations required careful hand detailing.

The result

Both tanks were completed on schedule — 13 days in total for the two tanks (520 m²) — and handed over watertight.