The light steel frame building sector is bucking the recession trend with a growth forecast of 10% for the 2009 calendar year
Compared with a 17% decline in the real value of residential buildings completed in the major municipal areas in South Africa during the first half of 2009, this forecast reflects a growing preference for light steel frame building as alternative construction method, says John Barnard, director of the Southern African Light Steel Frame Building Association (SASFA).
Barnard says LSFB technology is generally used in low to medium rise buildings, ranging from residential buildings to offices, clinics and hospitals. Residential building is the sector that has taken most strain due to the economic slowdown. “Despite this a mid-year poll of SASFA members indicated that demand for galvanised steel by the LSFB industry would grow by an expected 10% this year.”
He says that while steel demand for light steel roof trusses constitutes a large percentage of the market, the demand for complete building systems, which include wall panels, is growing. It is expected that some 20 000 tons of high strength galvanised steel will be used during 2009 for light steel frames and trusses. This equates to 1,9 million m2 of floor area for roof trusses and more than 250 000 m2 for buildings and other structures.
Three companies, Mitek, FrameMaster and Vela SBS, broke new ground when they were awarded SASFA accreditation for their light steel frame building systems following evaluation by the University of Stellenbosch. This accreditation confirms their compliance and adaptability to South African building standards.
Barnard says accreditation will in due course be granted on four levels – for a building system, for manufacturing and assembly, for erection and for building completion – and audits will now proceed on manufacturers using accredited systems.
Dr Hennie de Clercq, executive director of SASFA’s parent body, the Southern African Institute of Steel Construction (SAISC), noted three key aspects counting in favour of light steel frame building. “LSFB presents excellent export opportunities since complete systems can be transported across borders, it is attractive as a green technology due to its energy efficiency and the sustainability of steel, which can be recycled, and compliance with SANS 204 detailing energy efficient buildings, which will become mandatory in future.”
“In our experience, few elements in the construction process are as important as the structure of the building,” says Wayne Miller of BlueScope Steel. “More and more, trusses and framing are considered to be critical to ensuring the security, value and service life of a building.”
Steel frames can be pre-punched to allow electrical and plumbing services to be installed quickly and efficiently, while waste is minimised by taking advantage of off-site fabrication of building frames, notes Miller. “Lightweight steel frames and trusses are quick to erect on site, requiring less energy and saving time. They are also more economical to transport to site and, having lower mass, leave a lower carbon footprint than heavy steel. Finally, light steel framing offers immense advantages in aggressive climates such as found in South Africa. They are impervious to hostile insect infestations and will not burn, thus reducing the risk of fire spreading throughout the entire structure of the building and are quick and easy to erect, so assisting with the country’s growth and development imperative.”
Miller does say, however, that the company has noted a lack of information and knowledge in South Africa about the true advantages of quality, hi-tech and modern coated steel products among many practitioners of the built environment, as well as building material suppliers.
A unique solution
Two recent Johannesburg projects illustrate the potential and diverse use of LSFB technology: sound rooms for the international broadcast centre for the 2010 Soccer World Cup at Soccer City, which are being built by Molapo Projects, and the new food-court and restaurant area at the Eastgate shopping centre in Bedfordview
More than 4 000m² of walling with 6m spans between columns and up to heights of 10m were designed and manufactured in Vela’s factory in Isando and installed by specialist lightweight contractors Browndeck. “We believe that these dimensions make these walls one of the largest ever constructed in lightweight steel in this country,” says Vela MD Brent Harris
Grinaker-LTA contracts director John McLaughlin says that, being built on top of a parking area, weight was a critical consideration for this project and Vela’s solution was ideal. “We considered alternate solutions and Vela’s was the most cost-effective given the special requirements and the fast track nature of the contract. We are satisfied with the results,” he said.
In all there were four structural wall types erected on the Eastgate project: acoustic walls; screen walls; feature cavity walls and standard walls. They all included structural lightweight steel frames, various types of board cladding, skim plaster and internal insulation giving them their required characteristics.
Vela contract manager, Wayne Cumming, says Vela’s design and manufacturing process followed a fixed procedure. “All our designs were signed off by an external engineer and our subsequent working drawings then approved by Grinaker’s engineers before production at our factory commenced.”
“Once the primary structural steel frame was erected by other contractors, its dimensions were accurately measured to ensure the perfect fit of the Vela panels, which were rolled and pre-assembled in the factory and delivered to site on a just-in-time basis,” Cumming says.
The main advantages of the system are:
* The speed of erection of lightweight steel structures translates into significant cost savings derived from shorter programme and lower P&G’s.
* The overall reduction in weight of the system translates into significant cost savings in foundation design.
* Due to the thinner wall profile, the usable interior space, with the same stand coverage, is larger than if conventional materials were used.
* Light steel frame walls provide excellent insulating properties leading to savings in energy. Also, adding to the environmental and sustainable benefit is the fact that the steel is recyclable and there is minimal waste removed from site.
* Easier installation of services – service holes are pre-punched in the wall panels for services to run horizontally or vertically the wall panels without the need for ‘chasing’ walls.
Cumming says this was the company’s first commercial project for Grinaker-LTA, and that its success has led to a second project supplying Grinaker-LTA with 560m² lightweight walling for the new Heineken brewery in Kliprivier.
A new generation of living comfortably
With global warming on the increase and our natural resources on the decrease, the current electricity crisis in South Africa is only going to get worse. Most of South Africa’s electrical energy is coal fired, and unless energy efficiency measures are taken, the demand for electricity is expected to exceed availability and become very expensive.
The use of insulation in buildings is critical to the conservation of electricity and our natural resources. Cavitybatt is a wall insulation used in steel frame homes, timber frame structures and dry walls systems. Cavitybatt offers exceptional thermal and acoustic performance not to mention the outstanding fire properties. It is manufactured form Glasswool, which is non-combustible and has excellent thermal resistance values (Rval) which greatly contributes to optimising the indoor climate and to the management of household energy consumption.
Using Cavitybatt benefits not just the home, but the environment too. Reduced electricity consumption results in a decrease in the emission of greenhouse gases and thus places less demand on natural resources. For example, every kilowatt/hour of electricity saved means one less kilogram of carbon dioxide released into the atmosphere by power stations.
Passive fire protection
FireSpec specialises in both active and passive fire protection measures, services which now form part of a unique offering to the South Africa market. Recently the company was involved in supplying signature passive fire control product FireSpec Fireboard CS to a highly acclaimed redevelopment at 11 Adderley Street, Cape Town.
FireSpec Fireboard CS is one of few passive fire control boards available in South Africa. It revealed its versatility by being used as exterior cladding for the walls of the atrium at 11 Adderley Street. Adam Rodger, general manager for FireSpec’s Passive Division says that the board can even be used of innovative ways. The heart of the product, however, is its two hour fire resistant nature, as tested and certified by SABS. Panels are approximately 1,2m x 2,4m in size and 9mm thick and contain no toxic or hazardous materials, nor do they emit these under fire. The product is moisture resistant and can be skim-finished and painted one side, or simply painted on the smooth side.
Rodger says that the product can be used equally successfully in cladding structural steel, for ceilings, roofs, floors, partitions and external walls. It finds specialised application in ventilation and smoke extraction ducts as well as in electical or mechanical services enclosures.
Growing in popularity
“We expect growing support from architects, as light steel frame building offers advantages with regard to energy consumption (embodied as well as operational energy) when compared to conventionally built masonry structures, recycling of materials, logistics, speed of construction and quality of finishes achievable,” says Barnard. Yet contrary to elsewhere in the world, the South African public is not yet generally used to framed structures for low rise buildings, such as houses. “It is, however, accepted as common practice for high rise blocks of flats, or shopping centres and offices. There may be some mindset challenges to overcome. We do expect wider acceptance now that the SABS Standard – based on the SASFA Code – has been published as SANS 517:2009,” he explains.
Although this is still a relatively new technology in South Africa, some new trends have recently emerged. “A new trend is the use of LSF as infill or facade panels, in steel or concrete framed buildings such as shopping centres or offices. It makes so much sense, as the LSF wall panels are much lower in mass than masonry walls, and yet it provides the required thermal insulation and structural capability. It is quicker to install, and does not cause a lot of rubble,” Barnard concludes.
BlueScope Steel on 021-442-5420
FireSpec on 021-685-1111
Isover on 011-360-8200
SASFA on 011-726-6111 or www.sasfa.co.za
Vela Steel Building Systems on 011-397-8742
lightsteel1.jpg: Primary steel frame being erected prior to fixing of lightweight steel.
lightsteel2.jpg: Cladding of lightweight steel frame wall.
lightsteel3.jpg: Lightweight steel acoustic and feature wall.
lightsteel4.jpg: 10m high entrance wall and canopy constructed with lightweight steel.
Lightsteel5.jpg: At the 11 Adderley Street redevelopment, steelwork is clearly visible with the fire control boards in the atrium painted red.