The November 2010 issue of Building Today contained an article under the heading New research questions steel frame code compliance.
This article, sourced from Carter Holt Harvey (CHH), is based on a report conducted by Green Being Ltd with the support of CHH, which compares the thermal performance of house framing in New Zealand.
The National Association of Steel Framed Housing (NASH) has reviewed the report and found that some specifications within it are inconsistent with common steel framing practice. NASH is working with Green Being Ltd to have this rectified.
Thermal breaks must always be employed, and NASH points out NZBC E3/AS1 1.1.4d requires a thermal break. Some of the suggested thermal breaks in the report are not recommended by NASH — in particular standard Cavibat battens are not suitable for use on steel framing.
A new model has been developed for use on steel framing, which has some of the cells of the batten filled with PU foam to give a greater R-value.
NASH has produced a technical bulletin, NASH N-10 Thermal Break & Cavity Construction, which outlines good/better/best thermal break solutions. This can be downloaded free of charge at www.nashnz.org.nz/publications/nash_publications.html.
NASH board member and New Zealand Steel marketing manager Chris Kay says since early September CHH has been conducting a campaign to raise doubt around the suitability of steel framing in New Zealand.
“The reality is steel framing has been used in New Zealand since the early 1970s and overseas, including Australia, UK, USA, Japan and the Middle East,” Mr Kay says.
“Nowadays, steel framing is regularly being used for one-off, architecturally-designed homes and by some of New Zealand’s largest group home builders, including Golden Homes and Stonewood Homes.
“Recent non-residential projects incorporating steel framing include a number of McDonalds restaurants and school projects, including Clearview Primary School in Rolleston, built in record time by Mainzeal.
“A number of associated building products manufacturers, including Winstone Wallboards and James Hardie, provide technical support for fixing their products to steel framing, and PlaceMakers now has a steel framing offer.
“New Zealand Steel launched the AXXIS Steel for framing brand to give kiwis another option to traditional timber framing.
“Choice is good for the consumer and the rapid increase in sales is proving the demand,” Mr Kay says.