The Viking Warm Roof system renders a more energy-efficient building — warmer in winter, cooler in summer. This BRANZ appraised system (no. 713) comprises a layer of rigid Kingspan polyisocyanurate insulation installed on top of a substrate (plywood, concrete or steel) with a Viking waterproofing membrane system installed on top of that (a vapour barrier is also required in Climate Zone 3). A Viking Warm Roof can achieve the Building Code's H1 minimum R-value requirement for roofs of R-2.9, with just 75mm thickness of Kingspan insulation.
While suitable for new-builds, the Viking Warm Roof system is commonly used as an overlay solution for re-roofing a building. This can be extremely useful seeing as Building Consent isn't required providing the existing substrate (which isn't being replaced; just 'overlaid') has satisfied the minimum 15 year durability requirement under B2.
Other benefits of a Viking Warm Roof overlay include:
- It avoids having to relocate building inhabitants and contents;
- With a warm roof, the dew point is transferred to the outside of the building rather than finding itself in the ceiling cavity, so it's a healthier option;
- A tapered insulation panel option is available to promote water-shed. This negates the costly carpentry required to re-pitch a flat substrate to the minimum slope of two degrees;
- There is no dumping of the old roof, or the need for scaffolding / shrink wrap to cover the exposed building during the reroof process;
- The rigid insulation will stiffen and brace a plywood or steel substrate, but remain sufficiently light for a building structure not to require reinforcement;
- The energy savings from the high R-Value can pay for the warm roof overlay within ten years (depending on the thickness of insulation installed).