SA Affordable Housing May - June 2019 // Issue: 76 | Page 26

FEATURES
‘Reframing’ construction
in southern Africa
Light steel frame building offers quality, and energy-efficient and
affordable construction which is growing in popularity.
By the Southern African Light Steel Frame Building Association (SASFA) | Photos by SASFA
T
he growth trajectory and incremental increase in the
popularity of light steel frame building (LSFB) in South
Africa has been nothing short of remarkable. In 2004,
when the CEO of the Southern African Institute of Steel
Construction (SAISC) visited Australia to evaluate light steel
frame building, this construction technique was little-
known in South Africa. Today, this relatively new building
method is now both widely accepted and frequently
used locally.
"The growth in the popularity of LSF construction locally
is due to its inherent innovation, and due to the fact that it
reduces building costs, in a number of ways," explains John
Barnard, director of the Southern African Light Steel Frame
Building Association (SASFA), a division of the SAISC.
LSF AS A BUILDING SOLUTION
LSF is increasingly being used for roof structures in the low
cost and affordable housing sectors. Thousands of smaller
houses have been built using LSF roof trusses, due to the
advantages offered that include incombustibility, light
weight, accuracy, straightness of elements and quality-
certification, countering all the shortfalls of other materials.
LSF has at this stage not been widely used for large
affordable housing projects. One large project in Delft was
completed a few years ago. This unfortunately caused a
reaction in the brick manufacturing industry, which
appeared to consider this as an intrusion into their domain.
The SA National Defence Force (SANDF) embarked on a
project in 2017 to build four three-storey blocks of flats in
Durban, KwaZulu-Natal. This project was successful and
similar projects are being planned.
Barnard explains that a major advantage of LSF building
is that a structure takes much less time to complete than a
similar brick and mortar building.
“As the construction team can finish the outer shell of the
building in a much shorter period, work on the inside of the
building (completing internal lining, ceilings, tiling and
painting) can get underway much earlier – as can the
installation of services (water and electricity),” he points
out, adding that, in addition, having the outer shell
completed earlier means that the building can also be
secured against unauthorised access much sooner.
“LSFB should however not be confused with
prefabricated building. In LSF building, the supporting
frame is made from thin gauge, high-strength galvanized
steel sheet, which has been cold-formed into lip-channel
sections. These sections are joined using rivets or self-
tapping screws to form strong wall frames, roof trusses and
floor joists,” Barnard advises.
The Assupol building in Summit Place, Pretoria East. All external
walls consist of LSF panels, clad with Etics on the outside and
fire-resistant gypsum board on the inside.
The wall panels are clad using fibre-cement and gypsum
boards, fixed using battery powered screw guns to install
the self-drilling screws. Insulation (glass wool) is installed
in the wall cavities to provide the thermal efficiency and
enhance the acoustic properties of the walls.
According to SANS 517: ‘Light steel frame building’, glass
wool is a deemed-to-satisfy solution for both thermal and
acoustic insulation. Other types of insulation can be used
but will need to be supported by a rational design by the
engineer or architect to motivate why the alternative
is suitable.
An important aspect of insulation is that there should
not be any gaps, or else the thermal or acoustic
performance will be negatively affected. As the LSF studs
are typically at 600mm spacing, glass wool insulation is cut
to size into bats which fit neatly into the cavities in the LSF
wall panels.
Services such as plumbing and electricity, can be
accommodated by making a cut in the glass wool bat.
Installation is not as easy with other rigid insulation
materials. Injected expanding foams can also be used,
provided it complies with fire regulations.
BENEFITS OF LSF
As far back as 2013, the fast food chain McDonald's built an
outlet in Cape Town which employed LSF in its construction.
In this project, material wastage was reduced by 30%,
transport costs by 80% and carbon footprint was also
significantly reduced. The savings on construction time
were of such significance that McDonald's were able to
open the particular outlet four months earlier, something
See more on page 26
24
MAY - JUNE 2019
www.saaffordablehousing.co.za