Does LSF really steel the show?
First Published by BUSINESS DAY, Home Front
Date: 08 May 2015
Journalist: David Steynberg
The use of alternative building systems like light steel frames is growing on South African consumers but does this new method really deliver the goods?
Since about 2005 the concept of using light steel frames (LSF) instead of traditional masonry walls has slowly become more and more accepted in both the residential and commercial building sectors in SA. In 2013 a market survey conducted by the Southern African Light Steel Frame Building Association (SASFA) indicated that a total of 500,000m2 of LSF buildings were completed in that year alone, across all property sectors.
"LSF is used for different building types. In a recent survey the industry reported that some 30% of all LS.F was going into residential buildings, 40% into commercial and office buildings and 30% into schools and clinics," says SASFA director John Barnard. "That would indicate that about 150,000m2 of housing floor area was built."
This translates into 500 homes of 300m2 each. Barnard says that while it is still a relatively small percentage of all building, it is growing rapidly year on year.
One proponent of the technology is Chris Smith, CEO of Razorbill Holdings, a company that supplies and installs LSF to various sectors in SA as well as to markets north of our border. His company is involved in alterations to existing buildings right through to upmarket residential and commercial developments.
"We have been involved in residential projects that were more than R4m on a single house, and commercial and institutional projects that were more than R18m a project," he says. "The application range is very wide; however, the technology is well suited to deliver exceptional, quality green buildings in the affordable-market bracket of R350 000 right up to the higher-end market of R1,5m."
"The industry reported that some 30% of all LSF was going into residential buildings"
In SA, the acceptance and application of LSF technology is being driven by policy makers as well as by home owners who are seeking to reduce the time taken to build residential housing and save on the day-to-day running costs.
Are transport costs really lower?
The LSF camp is adamant that the sustainability benefits of this form of building outperform those of traditional daybrick-and-mortar builds and they cite lower transport costs. "The walls for a 200m2 brick house have a mass of some 180 tons (90 tons for bricks and 90 tons for cement and sand). That equates to about 18 truckloads of materials." says Barnard.
"The mass of the light-steel frames, the insulation, the lining and the cladding amounts to 11 tons for the same house - less than 10% of the masonry house. It is clear that LSF offers a huge logistical cost advantages in terms of transport and handling."
But the Clay Brick Association points out that while steel frames and cladding must be transported across the country from its place of manufacture (often Gauteng), clay brick are usually produced within 30km of where they are used. This not only substantially decreases the overall transport cost and carbon footprint, it also support local businesses and creates jobs in rural areas.
Is construction really faster & more reliable?
"The speed with which LSF can be completed depends mainly on the builder. Proper detailed planning up front is required. The owner should also rather spend an extra work on planning so as to minimise changes to the plan during the building process.
"If all runs smoothly, a 300m2 house should be completed in less than three months." This saves anyone building a new home significantly, as penalties and levies are charged on land is high-end estates. Getting the house up quicker means penalties are not incurred.
The Clay Brick Association of SA points out that only a handful of contractors know how to build steel-structured housing and they are inexperienced as the technology is very new in South Africa. This means that construction seldom DOES run smoothly - as the LSF manufacturers admit - upfront planning is essential and there is no flexibility for the homeowner after plans are drawn up.
Bricklaying is only a small time and cost within the construction of a home, and qualified bricklayers with 30 years experience are available cheaply and locally. The speed of construction under local conditions is well known, and problems are easily anticipated.
And because clay bricks are modular, it is easy to make minor adjustments to suit conditions on site, or if the homeowner changes his mind - both during construction or 5 years later!
What about lifetime energy costs?
The Clay Brick Association of SA reminds us that reduced costs and convenience during construction are insignificant compared to the long term costs and carbon footprint of heating and cooling over a lifetime of use.
"Lower construction costs often benefit the developer, but not necessarily the homeowners," explains Jonathan Prior, Executive Director of the CBA.
"The density that makes bricks heavy to transport, is exactly why they have such excellent thermal buffering. The high thermal mass of clay brick keeps the home cooler during the baking heat of the South African summer, and warmer on cold winter nights - reducing the need for air-conditioners or heaters. And that is a cost saving all year, every year.
According to clay~brick manufacturer Corobrik MD Dirk Meyer, there has been a lot of misinformation published about the benefits or LSF in order to compete with more traditional technologies like clay brick. The Centre for Scientific and Industrial Research (CSIR) recently published findings that showed LSF, amongst other alternate building applications, outperformed clay brick.
But according to Meyer the research which is based on computer simulations rather than real-world conditions, was flawed.
Peter Kidger, marketing director at Corobrik, identifies research on lifecycle carbon footprint assessment done by Energetics in Australia as a case in point.
"The research was done on real buildings using sensors, and not by computer software that uses manufacturer-supplied baselines entered manually.
"WSP Green by Design research shows benefits in terms of the life cycle carbon foot-print and energy use: if you take embodied energy and operational energy and combine the two, clay brick even WITHOUT insulation in the cavity outperforms an LSF building WITH insulation at SANS 204 specifications." he says.
"It's clear that when it comes to clay brick embodied energy is higher as built than the alternatives, but in life cycle terms and what it can bring to energy efficiency is lower over a full lifetime cycle."
Sustainability aside, which construction method is cheaper?
Smith says that when looking at product costs, labour and professional services, the costs are 5 % to 10% cheaper. Barnard agrees: "It can be said in general that the materials used are not less expensive than for traditional building methods. But cost advantages stem from the speed of construction, smaller building teams and earlier occupation."
Meyer reminds us that :
- speed of construction of these new technologies is neither proven nor likely given the greater need for planning and inflexibility of design
- building teams may be smaller but are likely to offer their services at a far higher labour rate, and
- occupation dates are almost always based on material deliveries of later finishes like tiles, custom kitchen cupboards, and bathroom fittings rather than the early materials like bricks and mortar that are available at your local hardware retailer.
He also notes that even top-quality facebrick in a high-end home will be less than 7% of the total cost or the building. And that using innovative large-size bricks can reduce building time by 35%.
He puts the entire impact of wall construction on total time and costs in perspective. "You would spend more money on your kitchen finishes than on the bricks for your entire house." he says.
It's clear each method possesses benefits - from embodied carbon, thermal efficiency and cost point of view - but there is too little comparable research to announce an outright winner - for that we will have to wait a little longer for real-world examples of LSF buildings constructed and occupied in South African conditions.
In the interim, a good compromise may be to combine traditional and new technologies, as is the case in both developing and developed economies.
