Is lightweight construction the future for housing?

As an alternative to all-concrete, lightweight construction is increasingly seen as a more responsible construction option as we face up to the social challenges of climate change, increasing urbanisation and galloping demographic change... We take a closer look at these new techniques that could point the way to tomorrow’s cities.

According to some demographic forecasts, today’s global population of 7 billion could well be 9 billion in 2050... So we need to build all the houses and apartment buildings needed to accommodate all these people! That poses an enormous ecological, financial and societal challenge for all construction industry stakeholders, and begs a central question: how can we build better, faster and more virtuously?

Lightweight construction could provide a key response. This construction method uses materials like timber and metal to form building structures, instead of bricks and mortar. Far from being a fashion statement, this trend is essentially the globalisation of local traditional construction methods. Don’t forget that in Scandinavia, Japan and the USA, timber-frame construction is the norm! In the USA, 90% of all single-family homes are built using modular timber structures. In Norway, the houses designed by Norges Hus are built using this principle. Healthy and environmentally friendly, they comply fully with the latest thermal insulation and energy efficiency regulations. And let's face it: they have nothing in common with a log cabin!

Lighter weight with equivalent performance

“Lightweight construction offers a number of advantages”, explains Gilles Leva, Deputy Vice-President Marketing at Saint-Gobain. “For example, timber structures are much lighter than concrete ones, which is a major benefit in itself, especially in terms of extending existing buildings or adding an extra floor...” It’s an option that opens up new opportunities, because although the majority of extensions have involved single family homes until now, the combination of timber and concrete is now increasingly common in the urban landscape, and points the way to tomorrow’s cities. Cities that are more vertical. More virtuous. More responsible.

             To read: Let's fact-check the sustainable city concept.

London stood out distinctively as early as 2009, with the first 8-storey timber building, the Stadthaus. It was the highest in the world at the time! Since then, projects using timber in the construction of tower blocks and other buildings have sprung up worldwide. Timber is widely used in traditional Japanese construction, so even the new Olympic stadium in Tokyo has a structure of cedar and larch.

Timber is a strong performer 

There’s no denying that in terms of carbon footprint, timber is a strong performer. By trapping CO₂ throughout its growing life, this eco-material offers significant benefits in terms of reducing greenhouse gas emissions. The fact that it is a natural resource is another strength, because it is easily recycled and contributes to sustainable forest management. “That’s the other great advantage of timber!”, continues Gilles Leva. “Prefabricating timber frames facilitates rapid construction, and equally simple demolition! So from this point of view, timber is fully consistent with eco-responsible construction”.

But timber does not have the answer to everything because this resource is not unlimited and requires a reasoned exploitation. In order for timber construction to establish itself in the long term in places where it is not a traditional method, it will have to rely on the establishment of a professionalized timber industry and networks of dedicated prefabricators and installers to guarantee competitiveness and quality.

Is lightweight construction economical?

Is lightweight construction really more flexible, faster and more economical? It all depends on what we are talking about.

By offering the option to build faster, facilitate automation and optimise production processes by using prefabrication, lightweight construction really does reduce production costs, and therefore the construction costs of creating the affordable, repeatable and exportable housing the world badly needs.

But all that depends on the materials you choose. Timber frame or metal frame? The cost depends on resource availability. The fact that timber is widely used in Japan, Scandinavia and the USA is because the resource is readily available in those countries, and the construction industry has structured itself to use this material over a very long period, thereby keeping costs under control. Conversely, timber is clearly a scarce resource in the Middle East, making timber frame an inevitably expensive technique here.

These new materials really are lightweight!

Fully aware of the environmental issues raised by using timber and mineral resources, those companies involved in lightweight construction are therefore looking to a future in which increasingly light and durable innovative materials become available. At the top of that list is concrete made using plant fibre, which is proving increasingly popular on all construction sites because of its inherently high thermal insulation properties. Even more innovative, bricks made from recycled paper build lighter structures, at the same time as addressing sustainable development issues. The same goes for eco-friendly timber blocks, which are five times lighter than their traditional cousins. Of course the implementation of these materials must also be done with regard to the fire regulations in force.

Building fast and well with prefabrication

But in a world on a quest for sustainability, quality AND reasonable construction prices, the great revolution in lightweight construction is process industrialisation. More precisely, prefabrication. Flexible and easily modified to accommodate new uses, pre-engineered modules undeniably speed up the construction process by harmonising construction techniques worldwide.

Here’s an example... In Catalonia, Saint-Gobain has contributed to the construction of a 108-bed hospital designed solely around modular elements produced and pre-assembled in a factory. This technique enabled the building to be erected in just four months, rather than the more usual four years it would have taken using traditional methods. Working alongside partners SH Holz & Modulbau in Germany, the Group was able to renovate a children’s home in just three months. So what is the secret of these incredible performances? A set of custom-designed prefabricated and pre-cut panels. To strengthen its position in this promising market, Saint-Gobain has recently acquired Brüggemann, a company specialising in turnkey modular timber solutions for new-build and upgrading projects. It’s an investment that speaks volumes about the Group's ambitions for lightweight construction. The advantage of prefabrication is not only that it speeds up the construction process, but that it can also be used to convert spaces quickly to multiple new uses. All of which means building in a new way that involves thinking ‘reversibly’ and opting for adaptable solutions from the design stage forwards. It is on this basis that the Saint-Joseph hospital in Paris specified factory-dimensioned and pre-cut ISOVER F4 facades. Perhaps most importantly, they can be easily removed for recycling in the event of future expansion projects. In Russia, the teams of Saint-Gobain have developed a lightweight facade system that uses plasterboard, glass wall and cement boards on a steel framework. The advantages of this new system include rapid construction, excellent thermal and acoustic insulation performance and a smaller carbon footprint: its production generates 10 times less CO₂ than other traditional facade systems!

So there you have it: faster construction, more sustainable worksites and closely controlled costs... Traditional in some locations, alternative elsewhere, lightweight construction techniques seem to deliver an appropriate response to the environmental, economic and societal challenges we face as we attempt to provide energy-efficient, healthy, comfortable and more sustainable housing.

Crédits photos : Dan Kollmann/Shutterstock ; Watercolor_Art_Photo/Shutterstock