Poorly constructed settlements don’t just cause domestic hardship and ‘low prestige’; they also worsen residents’ mental and physical health, cognitive development and economic participation. Since low-quality housing often conflicts with building codes and zoning regulations, residents often risk being evicted or having their homes destroyed.
3D printing might make quality, legal housing affordable for people living in poor urban settlements. Printers can use cheaper, novel materials — recycled construction waste, or even clay and plant seeds — and also make possible more innovative, less material-intensive designs.
“3D printing might make quality, legal housing affordable for people living in poor urban settlements.”
Sally Murray, International Growth Centre (IGC)
Prototypes have already cut material costs, construction waste, labour costs, and carbon emissions by 50-80 per cent. 3D houses are also built more quickly: Chinese firm WinSun wowed the construction world last year by printing ten quality homes in just 24 hours, for US$5,000 apiece. Where land prices are prohibitive, 3D printing can respond with multi-storey apartments.
It sounds like a magic bullet. But things aren’t quite that simple. First, 3D printers are expensive, meaning the technology is only cost-effective at scale. They are also large and heavy, and so difficult to transport. Third, at current prices, the houses remain out of reach for the poorest families: a household earning US$250 a month could, at a stretch, rent (or with credit, buy) a US$5,000 home — but this overlooks the cost of the land and infrastructure that services the house, which may cost as much again.
Indeed, many informal houses — from Mumbai to Johannesburg, Phomn Penh to Nairobi — are in central locations earmarked for high-end development, with some plots worth more than US$90,000. It makes no sense for developers to build a permanent US$5,000 bungalow on such a plot, so formalisation of housing will often entail either the migration of residents to cheaper, more peripheral areas, or their consolidation in higher-rise apartments.
There are macroeconomic considerations, too. The construction sector is creating jobs and growth in many urbanising economies: it is directly responsible for twice as many new, stable jobs as manufacturing in Sub-Saharan Africa, and around ten per cent of GDP (gross domestic product) in China and India.  The question is whether, by bringing costs down, 3D printing could boost demand for new houses and create jobs, or whether, since printing requires far fewer workers per unit, it could result in medium-term job losses. Finally — and at this stage, most significantly — this is a really new technology. It has yet to be tested at any scale, outside what are effectively building laboratories. The next stage should be construction of a pilot neighbourhood in a developing country city, to discover the full costs and challenges of implementation in the field. If such a pilot is carried out, I believe all eyes will be on it.
Sally Murray is a country economist at the International Growth Centre (IGC), a research institution based at the London School of Economics and in partnership with the University of Oxford, both in the United Kingdom. She works in Rwanda, overseeing the IGC Rwanda’s research on urbanisation, energy, public sector performance and tax. She can be reached via Twitter: @sally_bm