Shout it from the rooftop!

Situated at the end of Princes Wharf on Auckland’s waterfront, is the eight-story, 187-room five-star Hilton Hotel, which opened in 2001.

Twenty years on and the hotel was in need of a new roof to replace the original membrane-on-plywood one; only this time, the client was looking for more thermal efficiency along with the usual requirements for water tightness; salt spray corrosion resistance; durability and the ability to withstand high wind pressure. The decision was made to have a warm roof installed, says Brendon.

“The building’s roof design was such that the large ceiling void, with its myriad of reticulated services, did not lend itself to a typical ‘cold roof’ insulation system where glass wool insulation had proven problematic; so installing a warm roof system; which would allow for a clear ceiling cavity, was the preferable option.

“It was important to the architect, Babbage Consultants Ltd, that this luxury hotel took advantage of New Zealand’s simplest, most energy-efficient and cost-effective warm roof system: Viking WarmSpan. Additionally, being avid fans of bitumen-based membrane products—because of the service history in New Zealand—Viking Torch-On was specified as the waterproofing layer.”

It was also critical that the roof was to be replaced without upgrading the original steel portal frames or purlins, as they still had structural integrity and the extra time and cost to replace those would have been prohibitive, says Brendon.

“Viking Roofspec systems can only be installed by Viking Approved Applicators; companies that have put their installers through our licensing programme. Once the project went to tender, long-time Viking Approved Applicators, Mohan Roofing Services, was awarded the contract.

“With the steel purlins being part of the original framework, after some minor modification, it was straight to work with fixing down the trapezoidal steel tray substrate. Having the building shrink-wrapped also allowed for trades to continue working no matter the weather conditions—which was an absolute Godsend.”

Viking WarmSpan is a simple, three-layer warm roof system that does away with the unnecessary components that can be found on other warm roof assemblies.

“Firstly, the steel tray sheets were sealed during installation and proprietary flashing tapes were applied to seal any transitions or junctions to complete a ‘built-in’ vapour barrier. Next, the insulation layer—75mm Kingspan polyiso panels—is affixed to the substrate using a proprietary two-component, polyurethane adhesive. This fully adhered system, using F.A.S.T technology, provides greater strength and wind uplift resistance than mechanical fixing, while avoiding thermal bridging at the same time.

“Lastly, Viking’s two-layer Gemini APP Torch-On membrane was installed over the polyiso boards, providing the waterproofing layer(s). Viking Gemini APP consists of a 3mm sand finish base sheet as the first waterproofing layer and a 4mm ceramic chip cap sheet installed on top.”

The Hilton Hotel is now completely watertight, with the Viking Approved Applicator completing this project to a very high standard. The roof looks great and will withstand the gusty conditions that the Auckland waterfront is prone to. Surrounding buildings higher than eight storeys, now look down on the Hilton Hotel’s tastefully installed, watertight and energy-efficient roof, which is backed by a 20-year warranty from Viking Roofspec.

Learn more about specifying WarmSpan for your next commercial or residential project.