NEW NZS 4246 INSULATION STANDARD
1 November 2016
The new Standard NZS 4246: 2016, Energy efficiency - Installing bulk thermal insulation in residential buildings, significantly reworks and replaces the old version NZS 4246: 2006. Although it is based on residential buildings, the methods it covers are suitable for other uses and types of construction, as well as new and retrofit situations.
Additions and changes
This new version of the Standard has had a slight name change and has added subjects such as installing insulation; in steel-framed construction and concrete slabs on ground. There are updates for installing insulation around light fittings/luminaires, and where there have been recent significant technology advances. The addition of more diagrams, photos and figures certainly helps with understanding and interpretation. Appendix B has been rewritten to align with the Health and Safety at Work Act 2015.
A very useful new feature has been the addition of tables to Appendix A that give the clearances of insulation from hot fittings and other building features. This is very good information for both designers and installers, as most people do not always know what clearances are required, for safety or by legislation. Although Masterspec has had information on clearances from recessed light fittings for some time, the information in these tables in Appendix A extends that both for light fittings and many more items.
At Masterspec we believe it is so important and useful we have now added further clearance information to most of our Masterspec insulation sections based on the Appendix A Tables. This covers clearances from, light fittings/luminaires, inbuilt recessed hot appliances, extracts, vents, pipes and roof underlays.
This new information in the Masterspec sections, may occasionally repeat some information that is also in other clauses, usually it is not identical and provides further detail. You do have the option to delete the repeated information, or leave both instances to reinforce the point.
Recessed Light Fittings/Luminaires
The new NZS 4246 refers to residential recessed light fitting types CA 80, CA 90, CA135, IC, IC-4 and IC-F for abutting or abutting and covering by insulation. However CA 80, CA135, IC and IC-F are cited in NZBC C/AS's and AS/NZS 60598.2.2: 2001. But CA 90, CA135, IC & IC-4 are only cited in AS/NZS 60598.2.2: 2016, which makes CA 90 and IC-4 alternative solutions. All clearances stated in NZS 4246 comply with AS/NZS 60598.2.2: 2001 or 2016 for residential installations.
Clearance to Roof Underlay
There is some confusion as to why there has to be a 25mm gap between insulation and the roofing underlay, it is often thought to be required to ventilate under the roofing. However, NZS 4246, 6.2.10, requires the 25mm clearance from the underside of roofing or flexible roofing underlay, to prevent the wicking of water from the roofing/underlay to the insulation. Ventilation, if the particular construction allows it, is only an additional benefit.
Obviously if the form of construction does not allow contact between the insulation and the roofing/underlay a gap may not be necessary.
Except for NZBC E2/AS1, 8.5.2, requirement for a 20mm gap under a membrane roof underlay to the insulation, most other documents like Standards and Codes of Practice have a very similar requirement to NZS 4246.
Masterspec has updated all the insulation sections under the CBI codes 4710, 4711 and 4721 for the new Standard, and added further clearance from insulation information to most of the sections under 4710 and 4711.