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Waterproofing Membranes Suitable for Geothermal Activity

Te Puia Wharekai

An Effective Waterproofing Solution for Moisture Affected Substrates in a Geothermal Location

Te Puia Wharekai

Installer: Holmac Limited
Architect: Allistar Cox

The latest tourist attraction in Rotorua is none other than Te Puia; a cultural centre educating visitors on New Zealand’s geothermal wonders and unique Māori culture. The vision for this cultural hub proved to be difficult requiring a slopping, multiple story building constructed over unstable, geothermal ground.  Working closely with architects from Allistar Cox and installers from Holmac; ARDEX New Zealand managed to resolve all external waterproofing needs for the 1,200m2 roof, combined with a 1,800m2 tanking system.

Due to a wet concrete substrate as a result from poor weather conditions a special two-layer torch-applied system using ARDEX WPM 114 vented base sheet and ARDEX WPM 189 capping sheet was selected to roof the cultural centre. ARDEX WPM 114 has special venting properties that allow moisture to vent through channels in the membrane. The moisture will eventually make its way to an opening, such as a parapet or an ARDEX roof vent, without the need for holes in the venting layer; making ARDEX WPM 114 a fantastic choice for coverage over substrates that may have moisture issues.

Being an area with a lot of geothermal activity, not only did the below-grade membrane need to waterproof the construction, but also ensure no harmful gasses were able to make their way into the building. With the two major gases in the Rotorua region being hydrogen sulphide and methane the membrane and the laps between sheets were tested to show no deterioration and to be completely impervious to those and other key gases. To ensure full security for the laps, and to reduce installation time on-site, the ARDEX Butynol sheets were measured to specification and fully vulcanised in ARDEX’s Christchurch factory after manufacture.

Overall the waterproofing solution provided was incredibly effective and provided efficiencies that only local manufacturing can. Completed in June 2018 thanks to Holmac and Allistar Cox; the Te Puia cultural centre is ready to let visitors in and keep the water out.