Countdown Colombo St Basement – Strong Waterproofing Solution!

Basement Construction at Countdown Colombo St

The Countdown supermarket at Colombo St, Sydenham,  Christchurch NZ, constructed around 2000, has a basement car park level. Due to a number of factors, including the need to reduce costs, the design team moved away from using a membrane to waterproof the basement area.

NOTE: New Zealand’s Countdown stores are progressively being rebranded as Woolworths.

Three-Part Solution

MARKHAM was able to assist with a holistic three-part system. The concrete itself was made waterproof by means of a combination of hydrogel admixture and spray-applied hydrogel treatment. The penetrations and joints were sealed with CONQOR 47B delayed swell waterstop gasket.

In the light of our current approach (this article is written in 2025) we would now approach this from the guidance of BS8102:2022. The project would quite possibly be regarded as a Grade 1B environment. (“No seepage. Damp areas from internal and external sources are tolerable.”) Our approach in 2000 is very similar to our current Type B structurally integral protection system, part of our BASE-TECT^® approach.

What Were the Short- and Long-Term Results?

The construction team were very pleased to find a holistic cost-effective approach that met the safety issues.

Due to the performance of this basement, the architects have become advocates for this system. The area is successfully used on a daily basis, without water penetration issues. The expense and practical difficulties of using a membrane were avoided.

Additionally, the floor slabs are highly durable due to the hardening properties of AQURON 2000. This helps the
floor withstand the day-to-day vehicle traffic. As a bonus, this sealer does not cause tyre squeal!

The structure has survived two major (and subsequent thousands of) Christchurch earthquakes with no remediation required. Clearly a well-designed and constructed basement along with the use of a robust waterproofing system.

The case study is available as a FREE PDF download.

To dig in deeper on ‘grades of environment’ according to BS8102:2022, relax and learn with our on-demand webinar.