Different strokes – The ins and outs of modular, temporary and alternative housing

By Kelly-Ann Prinsloo

South Africa is a country in transition. In the 22 years since Apartheid was dismantled, the government has been scrambling to right the wrongs that system perpetrated against its citizens. One of those wrongs was inadequate housing.

The government inherited a critical housing shortage, with the 1996 census reflecting a housing backlog of 2 202 519. Since 1994, the state has built 1.4-million housing units, providing more than five million people with secure homes.

As South Africa’s population continues to grow, so too does the housing deficit. And those South Africans living below the breadline are not the only ones who need safe, comfortable homes – many young South Africans are looking to alternative technologies to provide them with a place to settle.

Enter modular and alternative housing.

A modular alternative

Modular homes are sectional prefabricated houses that consist of multiple sections called modules. ‘Modular’ is a method of construction differing from other methods of building where the modules are constructed at an off-site facility, then delivered to the intended site of use.

Intastor Controlled Environments (Pty) Ltd, a company that designs, manufactures and install insulated modular panels, insulated roofing panel systems, insulated modular wall panels, and expanded polystyrene insulation was appointed to provide an expected total of 1 500 transitional residential accommodation units (TRAs) units at Delft, just outside Cape Town, in three phases. The first began in September 2011 and consisted of nearly 800 units including a community hall, spaza shops, and security facilities. This first phase was completed and handed over to residents earlier this year. Phase two, which commenced in November 2011, was for an additional 300 units to be handed over in early 2012.

The advantages of modular construction, an alternative to traditional construction, are clearly seen at Delft. Modular construction has proved to be successful in providing affordable accommodation at high volume delivery rates, while providing quality homes to some 800 families.

The resident families at the Delft site have responded positively to the project. The biggest advantages the homeowners have noticed are the energy-efficient insulation qualities of the units, which reduce heating costs in winter and let the coolness in in summer. Residents have also mentioned that keeping the internal walls clean is relatively easy and that, thanks to the slight elevation of the units above the ground, there is less dust.

The supply of residential accommodation units in kit form made it possible to utilize work teams drawn from the local community which were trained on site within a few days to enable them to construct a 24m² unit a day. These teams, typically comprising of six people per team, had only basic skills and little if any construction experience. Once trained, these teams are able to deliver a 48m² unit each day. The simplicity of the fully-engineered design and construction allows for minimum use of skilled labour and the almost total elimination of the traditional construction materials that draw out and tend to result in extended delivery timeframes inherent in conventional building methods.

The success of the Delft initiative has been built around the innovative application of ideas underwritten by an enlightened engineering approach, which makes use of modern building construction materials. A lightweight structural lattice steel grid platform anchored slightly above the ground on steel legs, requiring minimum soil levelling in most instances, forms the sub structure. Onto this is applied the damp proof course and base floor covering of timber or fibre cement boards. Insulated Modular Panels, manufactured by Intastor, are then bolted to the steel sub-structure, providing the walls in the form of pre-painted flat steel skins on a fire-resistant Isolite polystyrene core.

The use of colour and printed stone pattern on the steel skins externally enhanced the appearance of the units to be more appealing on the eye. Some internal walls were supplied in a steel skin with printed ‘Oregon Pine’ wood grain finish. The roofing panels were provided as a combined pre-painted IBR steel sheet externally with a 60mm insulated fire-resistant Isolite polystyrene core and a flat finished pre-painted ceiling finish internally supplied in 10.8m lengths. This provides total roof coverage in a single span reducing water ingress opportunities, unsightly joints and allows a natural roof pitch slope in both directions. It was possible to deliver eight complete units in flat pack kits per truck delivery with all components ready for installation within two hours of factory manufacture.

Staying within the modular framework of 24m² units Intastor was able to combine the standard module and provide the larger ancillary buildings associated with all small communities. A crèche, for example, was established in an older part of Delft itself, earlier in 2010 using the same process as described above. By staying within the bounds of the panel modules parameters one can with little difficulty, achieve endless solutions to many of the social and commercial needs centred around buildings today. The modular panel product offers a basic building core that can have any number of finishes applied, from cementitious coatings to mock weatherboarding, to achieve desired appearance.

Light steel frames lead the way

Another alternative housing material making waves in the industry is light steel frame (LF) building technology. A decade ago, LSF technology was a revolutionary new construction technique in South Africa. It gained traction quite quickly and today, it is a viable option that, in many cases, is more cost-effective and sustainable building material than traditional materials.

In 1994, the new government implemented a socio-economic policy framework to help alleviate some of the socio-economic struggles that many citizens faced. Between 1994 and 2001, over one million Reconstruction and Development Programme (RDP) houses, were built to accommodate five million of the estimated 12.5 million South Africans without proper housing.

RDP houses must be constructed cheaply, be reliable and able to withstand the general wear and tear that most houses face, whether from natural elements or from residents.

Enter Trumod steel frame construction, a long-standing member of the roofing industry that constructs between 400 and 500 light steel frame (LSF) roofs every month. Trumod’s LSF roofs are to be installed in RDP housing projects across Gauteng.

Mulder Kruger, managing director of Trumod, explains that LSF trusses are an ideal alternative to wood, especially when it comes to low-cost housing because – as the name suggests – LSF trusses are light. In most cases, LSF installations do not even require a crane to install them; they are simply lifted up by able-bodied workers.

“On the larger spans, timber trusses are so heavy that you actually have to hire a crane to install them,” says Kruger.

When it comes to RDP housing, cheaper is always better. That’s why LSF is a perfect material for low-cost roofing – the trusses are installed without the use of a crane, which can be expensive to rent and, in some parts of South Africa and other African countries, difficult to acquire. LSF trusses are also relatively easy to transport.

LSF can also be easily paired with concrete roof tiles, the cheapest and preferred roof tile type in South Africa. The tiles can be affixed directly to the trusses.

Another key trait of LSF, which perfectly suits the low-cost roofing sector, is the lack of maintenance. LSF trusses are made from galvanised steel and, if the manufacturer abides by South African National Standard (SANS 517) which specifies the grade of galvanising that is required, then, as Kruger says, “There is no maintenance whatsoever.

Modular construction has proved to be successful in providing affordable accommodation at high volume delivery rates while providing quality homes to some 800 families.1

1Modular homes are sectional prefabricated houses that consist of multiple sections called ‘modules’
Credit: Federal Emergency Management Agency
This article was originally published in Affordable Housing

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