History of Steel-framed Housing in New Zealand

The idea behind steel framed housing is to use light, strong, cold formed galvanised steel sections to make up the structural form in a more efficient manner than traditional timber construction.

Steel House frames were first used in New Zealand in the late 1960’s and the first steel framer, Stuart Thompson, commenced operation in Wellington in 1970.  There are now a number of steel framing operations throughout New Zealand.

Steel Framing is an increasingly popular alternative to timber in many countries.  For instance there are over 120,000 steel framed homes per year built in the USA and 150,000 in Japan.  In Australia steel framing has been used since the early fifties and now over 10,000 steel framed houses are built every year.

In the 1980s availability of hi-tensile zinc-aluminium alloy coated steel encouraged new systems development.

Computer technology arrived making frame detailing and manufacturing process control faster and more accurate.

Steel frame and truss manufacturing technology quickly caught up with timber frame technology and developed well beyond international practice.

Advanced joining systems and low cost screw and nail fasteners have made manufacture and construction easier, cheaper and more reliable.

Today’s framing represents the results years if research, testing and development and is a thoroughly engineered product.  Steel framing comfortably complies with the New Zealand Building code requirements and is approved by local authorities.

The frames consist of roll formed, channel sections, designed and produced using computer aided manufacturing techniques which can then be assembled to very tight tolerances.  Most framing panels are pre-assembled in the factory and then rapidly erected on site using self-drilling screws. Holes to allow for plumbing and electrical wiring are pre punched at the factory and plastic grommets are used to prevent damage to pipes and wiring.

One of the success stories of the New Zealand Steel framing industry is the companies manufacturing roll forming equipment for steel framing manufactures.  Companies such as Howick Engineering in Auckland have been making forming machines for the industry for many years and have been particularly successful in marketing their machines and technology in international markets as well as New Zealand.

Technology made and available in New Zealand is arguable superior to anything else available throughout the world.

History of Steel-framed Housing in Australia

(Adopted from an article written by Ken Watson, “The Development of the Residential Steel Framing Industry in Australia” (Steel Construction, Journal of the Australian Steel Institute, Volume 41 Number 1 June 2007)).

Kit homes with cast iron frames were imported from Britain into Australia in the 1850’s. Examples of these homes survive today and have been classified by the National Trust for their historical importance. The next example of steel framing occurred after World War II where about 200 homes were constructed in Canberra using bitumen coated steel.

The modern development of steel frames commenced in the 1960’s and led to the development of the welded frame which is still the basis for many frames constructed today. The system was based on grade 300 galvanised steel with a typical thickness of 1.2mm. The studies were typically 75x35x1.2mm plain channels. Manuals were developed for the design, fabrication and erection of steel frames and trusses. At this time standard sections were rolled by the large roll formers and fabricated by small fabricators.

The next round of development commenced in the early 1980’s. At this time a number of technological advances occurred that strongly influenced the development of steel framing up to this day.

These advances led to the development of systems where the house design was entered into the computer system and the cutting information was fed electronically to the programmable roll former. This saved significant costs in manufacture due to error minimization, material waste and work in process.

In the late 1980’s, Australia led the world with the use of G550 steel in house framing. With the development of more complex and structurally more efficient shapes, the advantage of the higher strength steel could be utilized and consequently the steel mass in a house was reduced. The thinner gauge members resulted in lighter frames and trusses which assisted with speed of manufacture and installation. The thinner gauges of steel encouraged the use of alternative methods of connection in the shop assembly of frames and trusses (e.g. clinching, rivets, screws). The thinner gauges also assisted the following trades, e.g. plasterers electricians, carpenters, plumbers, etc. in their ease of use of steel frames on site.

During the phase of development, Aluminum/Zinc alloy coating (ZINCALUNE®/TRUECORE®) replaced galvanizing as the preferred method of providing better corrosion protection due to its superior performance, with a life of two to four times that of the galvanized product.

Today the steel framing industry in Australia is highly innovative with many different systems. This creative and competitive environment has led to steel frames becoming a mainstream option for framing of houses and similar structures. All systems must comply with the requirements of the building Code Australia (BCA), which now references the NASH Standard-Residential and Low-rise Steel Framing Part 1 Design Criteria. The reference to old standards AS3623-0993 ‘Domestic metals framing’ has been withdrawn from the 2007 edition of the BCA and hence the NASH standard should now be adopted.