The dates
- 27 November 2025
- H1/AS1 6th edition in force. It no longer includes the schedule method.
- Until 26 November 2026
- The 5th edition, including its schedule method, can still be used.
- From 27 November 2026
- Only the 6th edition's calculation and modelling methods remain under H1/AS1.
What it means when you choose insulation
Under the schedule method, meeting a minimum R-value for each element was enough. Under the calculation method the designer works out the heat loss of the whole building and compares it with a reference building, so the R-value of each wall, roof and floor build-up matters, not just the batt on its own.
A batt's R-value is for the insulation material. The R-value of the finished wall or roof is lower once framing and the other layers are counted. Your designer or H1 calculation will give the construction R-value each element needs; choose the batt that achieves it in your framing.
How we can help
- Our H1 design service can do the calculation and specify the insulation and airtight layers together.
- Ask us for batt sizes to suit your stud or joist centres.
- Use the estimator to turn your areas into packs and rolls.
The schedule method calculator on this site is for consents lodged under H1/AS1 5th edition before 27 November 2026. For anything later, use the calculation method.