Westpac Charter House

Project requirement

The building of the three level basements required excavation down to 11 metres below street level and eight metres below sea level. The site is on reclaimed land. Ground contamination from its former use as a petrol station was mitigated with the introduction of sediment control and filter pumping systems set up on site. Further pumping control issues were not helped by one of Auckland wettest winters on record.


The Volclay Bentonite Waterproofing membrane and RX Waterstop were specified to fully encapsulate the three level carpark basement of Westpact Charter House.

The basement slab area was often under water with continual flow of water through the face of the sandstone wall.
Volclay Voltex DS & SWR Bentonite membrane, which was specified for its ability to cope with contaminated and saline conditions, was laid beneath the floor slab and fixed directly to the sandstone walls. The walls were poured insitu with RX Waterstop in all the cold pour construction joints.

On the vertical wall face at the sandstone and sheet pile junction and where the greatest water ingress was being experienced, Volclay Ultraseal SP was applied and overlapped with the Voltex. Ultraseal is compatible with Voltex.

Voltex and Ultraseal bond directly to the concrete through Volclay’s advanced needle puncture technology. Volclay membranes allow for fast and accurate installation in wet and difficult site conditions.

Project detailsCopy of IMG 0122

Applicator: Sansom Construction Services Ltd 
Builder: Hawkins Construction Ltd
Architect: Peddle Thorp Architects
Completed: November 2008


Project Siz:e 5000m2
Warranty: Volclay full system warranty, 20 years
QA Visits: 45
Hydrostatic head of pressure: 11m