Ctrl+P: The pilot project pressing print on homes

 

It is something of a passion project - Mr Moon was born and raised in Accrington, and the pair are funding the initiative themselves (although they are seeking investment and partnership with other councils moving forward). They purchased the site from the council in 2022, received full planning permission last year and hope to be onsite in quarter two of this calendar year. When built, the development will provide social homes for military veterans, local families on low incomes and others in housing need. The organisation is in the process of registering as a social landlord to take over management of the properties once built. 

 

So - with a major need for new housing and widely publicised limits on the availability of labour and materials - will this approach catch on more widely?

 

One of the major advantages with this form of construction is speed. “It’s phenomenal,” says Dr Kanavaris. “You can build a one bedroom house in less than 48 hours, potentially.”

 

“It has already shown great potential in areas like affordable housing and sustainable infrastructure,” adds Dr Mohammadali Rezazadeh, assistant professor of structural engineering at the University of Northumbria - who is currently leading a research project on the technology. “It is especially useful for housing shortages because it offers quick construction compared to the traditional way.”

 

 

The precision also means it is far more efficient than traditional construction, there is very little wasted material. “For a given section, you can save up to 50% of material just by using this approach,” adds Dr Kanavaris. 

 

There are also advantages over the forms of ‘modern methods of construction’ which have floundered in the UK in recent years. 

 

The rush into ‘factory built’ volumetric housing has resulted in some big losses - both for investors and the taxpayer, because the huge debt taken on to build up the factory facilities was never repaid in a big enough order book to make it profitable. 

 

But 3D printing does not have this problem, and neither does it result in the identikit houses turned out by factories. The final design can be modified endlessly by changing the blueprints. 

 

Indeed, this technology offers an attractive solution to the build quality issues that have dogged the residential construction sector for years. 

 

 

“The machine itself can be operated by three individuals. They can usually be set up in a period of between one and three hours,” says Mr Hulse. “You’re not reliant on drawing out the lines and getting the bricklayers to follow the plan, the whole thing is pre-programmed into the computer system via GPS, so once the blueprint is transferred into the system, it will print what it’s told. And if it does make a bit of an error, it’s wet concrete, you can stop and you can fix it.” 

 

All of this is good, but there are certainly challenges to overcome with this technology. First, while this process is automated and reduces the number of staff required onsite, it is still specialist - and we do not yet have many trained specialists ready to use it. 

 

“You need to have very well trained people to operate these machines. They need to be able to supervise the printing process, to ensure that if a problem is spotted, it can be fixed right there on the spot,” says Dr Kanavaris. 

 

The machines, and the mix of concrete which goes into them, are also not cheap. “The materials used to produce the 3D printed concrete or mortar are more expensive than traditional concrete, and you need the automated equipment: the robotic arms and the printing machines which are not cheap,” adds Dr Kanavaris.  

 

If the industry scales, prices will fall. But modern methods of construction can get caught in this bind in their early days - in order for prices to fall it needs to scale, but in order to scale it needs prices to fall. 

 

 

What about safety? The history of construction innovation is littered with examples of good ideas, which turned out to be less safe than expected when they entered the real world - from the ‘large panel systems’ housing towers of the 1960s to the cladding and timber technologies of the modern building safety crisis. 

 

Currently a lot of research effort is going into the safety of the product. Dr Rezazadeh explains that his facility is equipped to expose the structures to accelerated lifecycles and harsh environments, to test how they react over time.  

 

“In the laboratory, we can speed up this cycle of the harsh environment, so in a few months, you can get the results of what will happen if this specific structure is exposed to temperature change and high winds. We can get an idea of the long term behavior of this kind of structure,” he says. 

 

 

It is important that this research is done, so that regulations can be properly standardised and ensure safety in this form of construction. 

 

“Printed concrete does not normally contain large aggregates, like gravel and so on, because they clog the nozzle and reduce printed layer adhesion,” says Dr Kanavaris. 

 

This may ring alarm bells in the UK, where the country is still grappling with the aftermath of the ‘reinforced aerated autoclaved concrete’ (RAAC) scandal - where crumbling concrete structures pose a major financial and safety risk. 

 

 

Nonetheless, Dr Kanavaris is confident in the use of the technology for current single and low rise structures. “We would never go ahead with a technology that we suspect could compromise structural stability in the long term,” he says. “For the sites that are being built in countries like the UK, the elements are relatively low risk, and the designs have been validated by reputable institutions, so the risks associated with those structures are managed.”

 

In Accrington, Mr Hulse says their blueprints meet all UK requirements for structural stability. “We have to make sure what we build meets the requirements that would be in place for standardised UK construction,” he says. 

 

What is being proposed in Accrington is also not exposed concrete. The structure will sit inside an external shell, and it will appear to the naked eye as a normal housing development. “We’re not talking about Brutalist architecture, we’re not printing a concrete igloo for people to live in,” says Mr Hulse. 

 

Another question is how green all this is. Concrete is not a climate friendly material, and many architects have been trying to move away from it in favour of sustainable alternatives.

 

But 3D printing has some advantages - less concrete is used, less concrete is wasted. The build itself has less material, reducing the overall carbon footprint. And research is going into the production of green concrete. 

 

 

Concrete - dirty as it might be from a carbon perspective - does have significant advantages over its greener alternatives. It is versatile, non-combustible, structurally sound and doesn’t rot like wood. Its supporters hope this technology may prove a greener way to keep using the material. But there is a good deal of work required to get to this state. 

 

“Currently we’ve seen printing concrete contain twice or three times the amount of cement that is included in traditional concrete, which means it is more carbon intensive,” says Dr Kanavaris. “This is, to an extent, prohibitive when we’re talking about decarbonisation, but we’re seeing efforts lately for optimisation in the concrete mixes for 3D printing using much less cement than before and greener ways to develop it.”

 

3D printing has a good deal of potential, and if it does catch on - this ordinary looking development in Accrington may prove to be a glimpse of the future. 

 

“I don’t think 3D printing will ever totally replace traditional construction methods,” says Dr Kanavaris. “Not everybody can obtain access to this sort of equipment and the process is quite delicate. You need to have very good, very well performing mixes in terms of flowability and other properties and be able to control these properties really well on site. 

 

“But I do see, within the next 10 to 15 years, this being regarded as a relatively well established method to construct simple structural systems – such as houses, and other simple precast elements for example - in an affordable and rapid manner.”

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Peter Apps is an award-winning journalist and author of Show Me the Bodies: How we let Grenfell happen. The book was awarded the Orwell Prize for Political Writing in 2023. Apps is a contributing editor of Inside Housing