Warming the roof - Cladding and Roofing NZ
Warming the roof

Warming the roof

What is a warm roof? Well, it’s many things, but most critically, it is a roofing system designed for low slope roofs...

Words by ArchiPro Editorial Team

What is a warm roof? Well, it’s many things, but most critically, it is a roofing system designed for low slope roofs, in which the building is insulated from the outside, rather than the inside. This in itself has a host of benefits, most notably the fact that by installing insulation on the outside of the building, the dew point is also moved to the exterior rather than interior of the building envelope.

Having the dew point – the point where the hot and cold air meet and condensation forms – outside rather than inside, means any condensation created at this point is kept outside the building, mitigating the risk of any structural materials becoming damp or rotten due to condensation forming on or around them.

“It also takes away the need for venting from the roof,” Viking Roofspec’s Brendon Sutton says. “This means no air is escaping from the interior of the building out through vents in the roof, which, in-turn improves a building’s energy efficiency.”

But perhaps what is just as enticing about warm roof technology as these critical benefits, is its versatility in scope, design and installation.

Viking Roofspec’s warm roof system is created with rigid insulation panels called polyiso, made by Kingspan Insulation. “Their product/service offer is unique in that they provide the most comprehensive custom-tapered polyiso scheme in New Zealand,” Brendon says.

Viking WarmRoof

“We’ve just had this tapered scheme specified and installed on the Otago University Science Block, which is a standout project using this customisable solution.”

This tapered scheme allows Viking’s clients to send their roof plan (with the bespoke roof design they desire in terms of slope and profile) to Kingspan’s design team in the UniteKingdom who programme that roof and essentially manufacture a jigsaw puzzle of different pieces of insulation, each labeled for ease of installation, and then send it to New Zealand ready to be installed by a Viking Licensed Applicator.

“This allows a building owner to achieve a much greater level of watershed than can routinely be achieved with a low slope roof.”

Viking’s complete warm roof system is BRANZ-appraised, but additionally, the membrane options for waterproofing on top of the insulation, being Viking Enviroclad, and Viking GM Torch-on, are both BRANZ appraised and CodeMark certified.


Viking’s Warm Roof system was also re-tested following a change to the Fire Code clauses of the Building Code in 2013, and as a result, it now has the industry’s highest possible fire rating, a ‘Group 1S’ rating. “As far as we know, it is the only warm roof system in New Zealand that has achieved this level of fire protection.”

While warm roof systems are becoming increasingly popular in new buildings, both residential and commercial, they are also now seeing significant uptake as a user-friendly ‘upgrade option’ for existing roofs, Brendon says.

“In a lot of cases, particularly on commercial buildings, the warm roof system is being used as an overlay in situations where the existing roof, (pre-checked to ensure it’s still structurally sound), has some repair and maintenance issues that, prior to this system becoming available, would have seen significant expense and disruption caused by having to replace either sections of, or the entire roof.

Viking Enviroclad

“Whereas using the warm roof system as an overlay is a way to ultimately allow the tenants of a building to continue their day-to-day operations while the warm roof is installed on top of the existing roof. For example, we’ve done this a number of times with supermarkets where they were dreading the possibility of having to scaffold and shrink-wrap and therefore spend upwards of $50,000 before any work was started; let alone the cost of lost revenue through disruption or temporary closure. Our warm roof system allowed them to simply get on with the job with minimal disruption.”

Viking Roofspec’s warm roof system can be overlaid on existing steel tray or membrane roofing.

For new-builds, Viking also has the market’s first NZ engineer-certified warm roof-on-steel roof called ‘WarmSpan’, which simplifies warm roof design with substrate supports that can span as wide as 3.0m apart without compromising the structural integrity of the roof.

If you’re considering remedial work on an existing roof, or options for a new build, make sure you get in touch with Viking Roofspec on ArchiPro here to see what you could achieve with this progressive technology.

Viking WarmSpan
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