One of the best ways to achieve a high R-value flat roof in New Zealand is by using a warm roof with rigid board insulation. Of the insulation products available, PIR is widespread. PIR refers to polyisocyanurate, which is a thermoset plastic foam.

There are a range of PIR products available, but all have different capabilities. Comparing the compressive strength of the different insulation products is recommended. A strong product provides a solid foundation for the waterproofing and anything that sits upon it such as solar panels, air conditioning units and general roof plant. Enertherm has very high compressive strength of 175 kPa.

For flat roofing options, Enertherm makes up Nuralite’s warm roof system, comprising of the insulation layer beneath the Nuraply 3PM waterproof membrane and creates a fully warranted build-up with CodeMark certification. The insulation component in warm roofs creates a continuous plane and consistent long term. The structure and substrate is protected from thermal extremes and will remain stable for its lifetime.

Enertherm insulation is extremely efficient per square metre. When compared to other insulation materials such as EPS, XPS and glasswool, a higher insulation value is achieved with a thinner board.

Greater thicknesses and R-value can easily be achieved by installing two layers of a thinner board. 100mm (R4.5) of Enertherm for Zone 1 and 2, and 120mm (R5.45) for Zone 3 is better practice than meeting code minimums.

It can be installed over various substrates for a flat roof application such as plywood, concrete or metal tray. It can even be installed on existing buildings as an overlay or a tapered option.

Tapered insulation can provide falls in one direction to a gutter or level valley, or in two directions to form falls and crossfalls. Often it is used when the roof fall needs to be a certain slope for the waterproofing membrane to meet council requirements.

Combining Enertherm’s thermal performance and excellent compressive strength, it provides an ideal solution for flat roof insulation.