Viking developed WarmSpan² to fulfil the NZBC’s H1 (5th edition) requirements for significantly increased insulation values. An engineer-tested system, exclusive to Viking Roofspec, WarmSpan² saves cost on material and labour while providing compliant R-values within the lowest possible height build-up.

Here’s how Viking approached the development of WarmSpan²:

Cost implication

Unlike H1/AS1, where the R-value requirement of R-6.6 for residential roofs under the Schedule method is the same nationwide, the requirement for H1/AS2 (commercial buildings over 300m²) has been more geographically considered, with its six new climate zones graduating from R-3.5 in Climate Zone 1, down to a whopping R-7.0 for climate zone six. Either way, the lift in thermal performance required to bring NZ into line with other OECD countries, is significant; so much so that the jump in cost has seen many projects either postponed, or worse still — cancelled.

System analysis

Leading up to the introduction of H1’s 5th edition in 2022, Viking recognised this cost challenge and analysed every possible component and installation methodology that goes into a warm roof assembly; including the support structure, to see where savings could be made without compromising the integrity of the roof assembly. 

Engineering

Viking then commissioned the services of highly respected engineers, Holmes Solutions, to test the robustness of their proposed new WarmSpan² system across several key criteria, with the supports of the substructure as far apart as 1800mm supporting a trapezoidal steel tray substrate, and 900mm apart for a tongue and groove plywood substrate. The results of the ULS (ultimate limit state) testing for stress loading were a revelation, as were the wind uplift testing results. 

Compliance

In short, the WarmSpan² roof assembly with its wider support spans is officially deemed compliant to the NZ Building Code. Viking have an engineering report from Holmes Solutions, outlining the test results to support this.

Reduced cost

The reduction in materials and labour by widening the span of the supports, results in an approximate saving of $4500, per 100m² of roof when compared to the 400mm and 900mm centres required for E2/AS1 compliant plywood and steel tray substrates respectively.

Viking believe a $40,000+ head start for a 900m² substrate before the warm roof materials have even been installed on top, is worth considering.

The WarmSpan² offers several other savings which include savings through installation sequencing, as well as the replacement of layers of primer and adhesive with thermally efficient insulation washers and screws to anchor the whole assembly.