Prior to the 5th Edition of the H1 changes, designing a home with a block or precast wall meant that the level of insulation needed to meet compliance was relatively low. Our Pink Batts masonry wall products are designed for this application.

But since the recent change in NZBC H1, if strapped and lined on the inside, solid masonry walls require the same level of insulation as a timber framed house; a construction R value of R2.0.

This now means the strapping must be 90mm to allow for the level of insulation generally required.

You may ask why this has changed; doesn’t the increased thermal mass of solid masonry walls allow for lower levels of insulation to be used? This is true, but when you insulate on the internal side, the thermal mass is no longer available to the interior to absorb and release heat.

What level of insulation should you be using?

In the case of a 150-200 series block wall, Pink Batts Classic R2.2 Wall will meet the requirements under the Schedule Method. Higher R-value wall products, such as R2.6 and R2.8 would enable better thermal performance and will also contribute to the overall heat loss profile under the Calculation Method compliance pathway, enabling a reduction in other areas.