top of page

What’s your real R-Value?
by NZ Foam – Warmer Forever™

NZ Foam New Climate zones.png

The MBIE is proceeding with changes to roof, window, wall, and underfloor insulation requirements by issuing the new edition of Acceptable Solution H1/AS1 and Verification Method H1/VM1 for housing and small buildings.


The new insulation requirements aim to reduce energy needed for heating residential homes of approximately 40% over minimum previous requirements by altering the R-Value requirements across several climate zones, and become mandatory in November 2022.


But what is an R-Value? And how do traditional insulation products weigh up with the building code changes compared to spray foam insulation? The thermal resistance rating or R-Value is the measure used most commonly in the building and construction industry to determine a material’s ability to resist the transfer of heat.


While NZFoam can guarantee our R-Value based on the thickness our product is applied, R-Value numbers on other products’ packets can be deceiving  –  Fibreglass has shown to be lower than advertised.


When a US Department of Energy-funded laboratory looked into the difference between R-values (which measure insulation’s ability to trap heat) on the label versus in the walls, they found that even “perfectly installed” fibreglass insulation had R-values 11% lower than on the label. “Commonly installed” fibreglass insulation dropped to 20% lower than labelled.


With spray foam insulation, the R-value you choose to install will be the R-value your house enjoys - for the life of the building.


While fibreglass’s performance reduces over time, spray foam doesn’t change.


So, what is the single most effective way to improve your home’s performance and save money on energy costs? Seal gaps to prevent heat loss from air movement.


This is why closed cell polyurethane spray foam has the highest thermal resistance (R-Value by thickness) of any insulation product available globally. It fills cracks and seals drafts. It does not settle or sag and can be applied to awkward areas, making it the perfect solution for the Building Code changes.


Closed cell foam has been used in New Zealand as insulation in industrial applications since the 1970s and is growing in popularity as a residential product - as more discerning home-owners choose comfortable, high-performing homes.


To learn more about the benefits of spray foam insulation, head to

NZFoam Spray Foam R-Values Table.png
bottom of page