BRANZ House insulation guide
About the tool
The BRANZ House insulation guide is a practical tool that helps you choose the right insulation levels for floors, walls and roofs in New Zealand homes.
It shows how different construction options and insulation products work together to affect a home’s thermal performance (R‑value). The guide supports compliance with the New Zealand Building Code energy efficiency requirements (H1), but it goes beyond minimum standards by helping create homes that are:
- Warmer and more comfortable
- Drier and healthier
- More energy‑efficient and cost‑effective to run.
The guide includes downloadable tables and guidance material that reflect the latest insulation calculation methods used in Building Code compliance.
Download this tool
Updates:
- Further fix to error where the R-value for slab floors were higher than they should have been when adding floor topper insulation
- New images for timber framed floors
- A worksheet added which provides simplifications to help with calculation and modelling for steel framed walls
The guide is now in two parts:
- The tables of construction R-values for common construction options for compliance under H1/AS1 and H1/VM1 5th edition
- The accompanying House insulation guide text for guidance on insulation to meet or exceed H1 AS/1 and H1/VM1 5th edition.
H1/AS1 and H1/VM1 5th edition, amendment 1 apply to all housing (including medium-density housing, apartment buildings and other multi-unit housing) and to buildings other than housing up to 300 m2. That is the scope of this Guide. While it can provide some useful information for larger buildings, it has not been designed for use with H1/AS2 or H1/VM2, the documents that apply to buildings other than housing greater than 300 m2.
While the House insulation guide can be used to help demonstrate compliance with H1, its intent and its purpose extend far beyond that, to helping architects and designers create buildings that are warm, dry and healthy and have performance beyond the Building Code minimums.
How to use the tables
The House insulation guide tables show the construction R-values for different floor, wall and roof constructions with thermal insulation material of varying R-values. The construction R-values have been calculated using the same methodology as specified in H1/AS1 and H1/VM1.
The tables can be used in two main ways:
- To find the construction R-value (the R-value of the built system) for a given level of insulation
- To find the level of insulation required to achieve a desired construction R-value.
The tables have the target R-value for the particular building element, and the R-value is calculated from the construction options selected.
The construction options are selected in drop-down menus at the top of each table. For example:
- Timber-framed skillion roof: roof cladding, nogs or battens, rafter spacing, insulation R-value, secondary interior insulation layer or not
- Timber-framed roof with roof space: roof cladding, joist dimensions, secondary insulation layer or not, joist spacing, insulation R-value and conductivity
- Framed walls: type of wall cladding, exterior secondary insulation layer or not, bracing/rigid air barrier, primary frame (timber or steel, and thickness), interior secondary insulation layer or not
- Concrete slab-on-ground floor: type of slab, perimeter insulation or not, brick veneer walls or not, floor topper insulation or not, wall depth, area-to-perimeter ratio
- Suspended timber floor: joist height, insulation material conductivity, lined or unlined, joist spacing, R-value.
The drawings on the tables are indicative only, illustrating general cladding, framing and lining options. They are not detailed working drawings and typically do not show the fixings, flashings and so on that are required in construction. For detailed construction requirements, designers will need to refer to other reference sources such as NZS 3604:2011 Timber framed buildings and Acceptable Solution E2/AS1.
Older editions of the BRANZ House insulation guide – the 5th edition and earlier – should not be used when working with H1/AS1 or H1/VM1 5th edition as some of the calculation methodologies have changed.
Background
The House Insulation Guide has been developed by BRANZ to support better building performance across New Zealand housing.
The current 6th edition has been fully updated to align with:
- Building Code Acceptable Solution H1/AS1 (5th edition)
- Verification Method H1/VM1 (5th edition, Amendment 1)
It applies to:
- Stand‑alone houses
- Medium‑density housing
- Apartments and other residential buildings
- Non‑residential buildings up to 300 m².
Older editions of the guide should not be used for current projects, as calculation methods have changed. The latest version ensures consistency with today’s compliance pathways and reflects improved understanding of how insulation systems perform in real buildings.