FAQs answered: Modelling insulation under the new Building Code requirements

In light of the recent Building Code changes we’re getting enquiries from Architects wanting to specify the perfect insulation products for their client’s new homes and renovations.

We’ve put together a handy guide answering some of the most common questions below.  If you’re after anything more specific, we’re happy to help.  Simply email our Technical team on tech@expol.co.nz or give us a call on 0800 86 33 73.

What are the new insulation requirements?

The new building code has expanded the number of climate zones in New Zealand from three to six, allowing insulation requirements to better reflect the different temperatures experienced in each zone.

The new climate zones are best shown on the map below. They follow local government boundaries.

The new R-value minimums vary between climate zones and building elements. These R-values represent a 40% reduction of the energy needed for heating compared to the minimum standard. See an overview in the chart right:

What EXPOL products work for underfloor?

EXPOL have developed R2.5 and R3.1 to meet and exceed the requirement in the six new climate zones.

Under Timber Floors Expol R2.5 is a new standard in underfloor insulation that meets the new Building Code standards in climate zones one to three.

Available in four widths of 360, 410, 470, and 560mm. At 100mm thick, the new panel design has variable concertina cuts. It contains recycled content and can be recycled at the end of its life.

EXPOL Black R3.1 is a premium underfloor insulation solution infused with Graphite. EXPOL Black R3.1 exceeds the new building code standards for climate zones four to six. Now 24% more efficient, this new panel design is 40mm thicker, and can be recycled at the end of its life.

Both products offer easy install.

What about concrete floors?

Expol has several products suitable for under concrete slab insulation. Below are the densities and thicknesses that we recommend to achieve the desired R-Values.

H Grade 24kg/m3 ThermaSlab 60mm R 1.67 75mm R 2.08 100mm 2.78

VH Grade 28kg/m3 ThermaSlab 60mm R 1.71 75mm R 2.20 100mm R 2.86

SLABX200 Insulation 60mm R 1.81 75mm R 2.20 100mm R 3.0

SLABX200 is a new generation, high performance Expanded Polystyrene Board specifically designed to deliver high compressive strength and improve insulation under concrete slabs. At R3.0 at 100mm, SLABX200 exceeds new Building Code standards across all climate zones.

What about the edge of the slab?

EXPOL has a slab edge insulation solution to also increase R-Values of slabs to meet the new insulation standards.

The product is manufactured from XPS (Extruded Polystyrene) and is highly moisture resistant — it can  fixed to the slab once the boxing has been removed.

The insulation will need to be plastered to finish the slab.

What are the general benefits of using EXPOL products?

EXPOL are proudly kiwi owned and operated.  Their high-quality products are tested and proven to meet Building Code requirements.

EXPOL products are the perfect solution for a sustainable build.  Many of their products contain recycled content and all manufacturing waste is recycled.  The products themselves are also recyclable at the end of life.

EXPOL operate throughout the country with branches nationwide from Auckland to Cromwell.  Manufacturing is done in New Zealand meaning no international shipping issues and delays.

How do I calculate how much EXPOL product I need?

We’ve put together a handy Floor and Slab Insulation calculator HERE.

Simply enter your details and the calculator will provide you with the best combination of EXPOL products to achieve your desired R-value.

EXPOL also have a dedicated Technical Team to help architects, specifiers and the trades.  The team are happy to get involved at the outset of large projects to ensure your insulation is calculated within the requirements.

Links to the products mentioned above:

New EXPOL R2.5 UnderFloor Insulation

New EXPOL R3.1 Black UnderFloor Insulation

EXPOL Thermaslab

New EXPOL SLAB X200

Need more information? See the full EXPOL product range here.