Containers an alternative?
Unavailability of land, lack of quality, slow funding response, increasing subsidies and inaccessibility of the housing market for low-income earners are some of the primary factors that pose a challenge to eradicating South Africa’s housing backlog.
Despite the commendable efforts of the state, policy implementations such as BNG (“Breaking New Ground”), monetary investment, NGOs and the built environment, the backlog is not decreasing at a sufficient pace.
In addition, the use of ABTs (Alternative Building Technologies) are considered negligible, with less than 1 percent of all constructed subsidy homes making use of construction materials and methods that differ from “traditional” construction.
This lack of demand can be attributed to unfamiliarity with different technologies and materials, and the societal norm of “the ideal home”.
The purpose of my research was to investigate the feasibility of a locally-uncommon ABT solution, namely the use of refurbished shipping containers (known as “Intermodal Steel Building Units” or ISBUs) for homes instead of conventional brick-and-mortar subsidised houses.
Container-home architecture allows innovative ways to create houses, from a single stand home to medium- and high-density living units several storeys high.
The modularity of a container home design also allows easy expansion of a home with additional units, vertically or horizontally.
The inherent durability of shipping containers also adds to the quality and robustness of an ISBU-home. But is it possible that ISBU architecture may provide a more suitable home than conventional brick homes for low-income earners?
To solve this question, I compared several optimised ISBU home designs (developed in collaboration with Caroline Naef, an architecture student from the Swiss Federal Institute of Technology Lausanne) with conventional counterparts in terms of cost, fabrication/construction time, quality, social acceptance and environmental sustainability.
Sampling of fabrication-, construction- and market data showed that ISBU homes can cost between 11-35 percent more than a BNG-type subsidised home dependent on the design type. However, the construction time of container homes is significantly less with a decrease of between 25-60 percent.
This reduction is highly dependent on the project size and conditions, but shows a general advantage over conventional construction.
A major drawback to ISBU-based construction is the supply and availability of refurbished containers, as well as transport costs.
These factors confine the size of feasible projects as well as the location to major and coastal cities, where containers are available and close.
To determine the social acceptability of ISBU homes, a door-to-door survey was carried out in a rural informal settlement in the Theewaterskloof Municipality. A majority of voluntary respondents preferred a traditional, single stand brick and mortar home to an ISBU home.
However, many respondents showed preference for an ISBU home if its design mimicked that of a conventional home. Therefore the demand for ISBU homes is highly dependent on its design.
The environmental impact of ISBU homes was determined from available eco-libraries and compared with data for conventional homes from previous studies carried out at Stellenbosch University.
The findings show that ISBU construction uses significantly fewer resources and incurs less waste generation. This is due to the “upcycling” aspect of used containers, as re-purposing the container units is more environmentally-friendly than scrapping and recycling.
The findings of my research show that ISBU homes are not feasible as a replacement for conventional brick-and-mortar subsidy homes; construction costs are higher, suitable refurbished containers are limited and projects are only feasible near large container supply centres (to keep transport costs low). The acceptability of such homes is also a limiting factor, as identified by survey respondents asking why they should prefer a “tin house” over a “strong, brick-home”.
However, commercial ISBU housing can significantly lower the cost of entering the housing market. This can raise the accessibility to homes for homeowners in the so-called “gap”-market (having an income between R3 500 and R15 000 a month, which represents roughly 25 percent of all households in South Africa).
In summary, container architecture provides an interesting method for constructing affordable houses, which explains the worldwide popularity of ISBU-based construction projects. Similar projects for student- and upmarket-housing have been completed successfully in South Africa and raised the awareness of the ABT with prospective buyers, investors and developers. However, persistent unfamiliarity with the technology and a higher cost for low-income earners overshadows the benefits of ISBU construction.
Therefore it will not prove feasible to replace cheap brick-and-mortar subsidised BNG houses with ISBU designs.
* Botes is a civil engineer. This article is based on his recent Masters in Civil Engineering (Construction Management) at Stellenbosch University.