BRANZ House Insulation Guide 6th edition

The Guide is now in two parts:

• the tables of construction R-values (spreadsheets for PC, Mac and an online Office365 version for PC and Mac)
• the accompanying guidance text (PDF)

From 3 November 2022, anyone using H1/AS1 and/or H1/VM1 to demonstrate compliance with Building Code clause H1 Energy efficiency in building consent applications can no longer use the 4th edition H1 documents but must use the 5th edition, Amendment 1.

The new H1/AS1 and H1/VM1 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.

Updated: 16 August 2023