PROVE the R

Compliant Installation and Proof of R-Value Installed 

26 March 2026 | IAONZ Technical Guidance

IAONZ promotes insulation installation that is compliant, evidence-backed, and aligned to the New Zealand Building Code and relevant standards. PROVE the R is our practical initiative to make it easy for builders, Building Compliance Authorities (Councils), and clients to verify that the specified insulation product and R-value were installed in your building.

What “PROVE the R” means

“PROVE the R” is simple job evidence that shows the installed insulation matches what was specified for the project (R-value, thickness, and location). It is not intended to add unnecessary admin - it is intended to reduce disputes, reduce callbacks, and protect building performance outcomes.  This has become increasingly important resulting from the recent changes to the H1 clause of the building code which has seen the increase in R-Value of specified solutions.

Why it matters

  • Thermal performance: the building users comfort and energy outcomes depend on what is actually installed.
  • Sign-off confidence: builders and BCAs need a quick way to confirm specified R-Values were used.
  • Fair competition: evidence-backed installs help distinguish compliant installers from poor practice.

What a compliant insulation install looks like

  • The installed R-Value matches the specification.
  • Coverage and continuity are consistent with the installation requirements for the product/system.
  • Workmanship aligns with relevant good-practice standards (including NZS 4246:2016 for residential bulk insulation, and any applicable updates).
  • Records are sufficient for project QA, client assurance, and any inspection queries.

The IAONZ R-Value Evidence Pack (recommended minimum)

IAONZ recommends the following as the minimum evidence set that builders and clients should expect on insulation jobs:

  1. Product identification: product name, R-value, thickness, and where installed (areas/levels).
  2. Batch/pack traceability: photo of packaging showing batch/pack identifiers.
  3. Delivery documentation: delivery docket and/or invoice or equivalent (photo/PDF).
  4. Install-day photos: photos showing the product installed, plus packaging/labels on site on the same day.
  5. Installer declaration: statement that the work was installed as specified, or any substitution was approved in writing.

How builders can use PROVE the R (practical controls)

  • Include a ‘no substitution without written approval’ clause in subcontract agreements.
  • Make the Evidence Pack a condition of final invoice approval and/or sign-off.
  • Keep Evidence Packs with the job QA records so inspection questions can be answered quickly.

A note on substitutions

Sometimes substitutions occur due to availability or design changes. Where a substitution is proposed, it should be: (1) identified early, (2) approved in writing by the principal/contract administrator, and (3) supported by evidence that the substituted solution still meets project requirements.

 

 

When it’s specified...
prove it was installed.

Evidence-backed installs protect homeowners, builders, and reputable installers.

 

IAONZ member commitment

IAONZ members commit to install in accordance with the New Zealand Building Code and relevant standards, and to operate a quality assurance process. Providing Proof of R through an Evidence Pack should be a straightforward part of compliant installation practice.