Why H1 compliance is driving a shift toward integrated envelope solutions

With the Schedule Method now removed from NZBC H1, architects, designers and builders can no longer rely on simple table-based isolated R values for compliance. Instead, projects must use either the H1 Calculation Method or full thermal modelling to demonstrate overall building performance — requiring envelope systems that support airtightness, thermal bridging mitigation, and consistent, predictable thermal performance.

IBS RigidRAP XT has emerged as a strong specification choice for this new environment. As a triple layer 18mm OSB3 rigid air barrier laminated with approved building paper and backed with a 10mm rigid foam panel, RigidRAP XT provides:

• A thermal break with R Value 0.41, exceeding the NZBC R Value minimum requirement of 0.25 for steel framing.
• A rigid air barrier that reduces pressure differences and supports a more airtight building envelope.
• Temporary weather protection for up to 90 days, helping fast-track construction and allowing interior works to proceed earlier
• Structural bracing, with tested systems for both steel and timber framing up to Extra High wind zones.
• Compliance through CodeMark certification, simplifying consent and specification pathways.

For architects designing warmer, healthier, energy-efficient homes under H1, these combined functions significantly reduce product complexity while improving modelling outcomes.

Understanding RigidRAP XT’s value for H1 modelling

RigidRAP XT is one of few NZ-made rigid air barrier systems that directly contributes to thermal performance through:

Integrated thermal break (R0.41)

The laminated rigid foam backing exceeds H1’s minimum thermal break requirement for steel framing, reducing thermal bridging and assisting in reaching the whole wall R values needed for modelling.

Improved airtightness

A rigid air barrier reduces air infiltration by limiting pressure differentials across the building envelope — a key factor in energy efficiency models. RigidRAP XT forms part of a weathertight external envelope when taped and installed correctly

Bracing + Rigid Air Barrier in One System

By combining weather protection, bracing and thermal value, the system reduces the number of components and simplifies specification for walls.

Suitable for a wide range of NZ projects

RigidRAP XT is suitable for:

• New residential homes
• Steel framed dwellings
• High performance, energy efficient builds
• Projects in Extra High wind zones
• Timber or concrete slab floors
• Re cladding or extensions