New Residential Homes

What does NZ Building Code H1 mean for insulation in a new build?

H1 sets energy-efficiency performance requirements. Compliance may be via calculation or modelling pathways, and it uses construction R-values (the whole assembly), not just the insulation product R-value.  The H1 calculations are prepared by your architect or designer and form part of the NZBC requirements for consent to be granted.  The Insulation R-Value forms part of that calculation. 

What’s the difference between “insulation R-value” and “construction R-value”?

Insulation R-value is the insulation product’s thermal resistance. The higher the R-Value the higher resistance it has meaning it provides better heat loss performance.

Construction R-value is the real-world performance of the entire roof/wall/floor assembly, including framing and linings—this is what H1 calculations require.

How do climate zones affect what I need to install?

Minimum performance requirements vary by NZ climate zone and by building element (roof, walls, floor, windows/doors). Your designer/specifier should select a compliant system for your zone and build type.

How do I avoid “thermal bridging” and cold spots in a new build?

Thermal bridging (heat loss through timber/steel framing and junctions) can reduce real performance. Common solutions include improved detailing, and in some designs, secondary insulation layers that materially lift wall/roof performance when done correctly.

What documentation should I ask for (quality assurance)?

For high-quality outcomes, request:

• Product data sheets (R-values, intended uses, limitations) - Select insulation from supporting IAONZ Manufacturers

• Installation statement confirming alignment with NZS 4246

• Evidence the design uses construction R-values suitable for H1 (often via BRANZ guidance/tools)
  This makes it easier to prove compliance and protect performance long-term.

Why should I choose an IAONZ Member instead of “any installer” or the cheapest quote?

Insulation performance is won or lost at installation. IAONZ Members commit to quality-first workmanship, correct material selection for the application, and install practices that protect the insulation’s stated R-value (no gaps, no compression, correct support and detailing).

The outcome is a warmer, drier home - and far lower risk of costly rework.

What proof do I get that the job was done properly?

IAONZ Members can provide clear documentation: the products used, where they were installed, and quality checks (often including photos where access is limited).

They also understand compliance expectations for NZ Building Code H1 (new builds/major renovations) and good-practice installation guidance such as NZS 4246—so you have confidence the work will stand up to scrutiny, resale, and time.