A pioneering housing project under way in Dundalk, Co Louth, signals the beginning of 3D construction printed (3DCP) social housing in Ireland, Louth County Council has said.

The Grange Close pilot project involves a unique collaboration between Louth County Council, Louth & Meath Education & Training Board (LMETB), Irish-owned company Harcourt Technologies Ltd (HTL.tech), and Roadstone Ltd, a CRH company, using 3DCP technology with the aim of providing a pathway towards an increased output of more sustainable, affordable, and efficient housing.

The project aims to utilise 3D construction printing technology to provide three three-bedroom terraced units that will have a floor area of c. 110 m² over two floors at Grange Close, Dundalk.  

Sequentially deposited through a gantry-based 3DCP machine

3DCP is a method of construction that involves using large-scale 3D printers on-site to create three-dimensional structures layer by layer. In this process, layers of ready-mix concrete (RMC) are sequentially deposited through a gantry-based 3DCP machine according to a digital model.

The result is the creation of the housing superstructure at a rate which is up to three times faster than is possible through traditional methods. This approach significantly streamlines construction processes and holds immense potential to revolutionise the construction industry in Ireland by providing faster, more cost-effective, and sustainable ways to build. 

"Its just the same as a concrete block wall. Instead of placing it manually by hand, the machine lays 50mm layers", said Justin Kinsella, MD and co-founder of HTL.tech. 

"As architects and engineers, we design the building in a digital model. That model is transferred to the printer and it tells the printer where to extrude material. The machine really just goes around and processes layer after layer of concrete and it works very quickly," he said.

HTL is the construction tech company who has brought this technology to Ireland.

It said that the houses in Dundalk will be built three times faster than they would using traditional concrete blocks and it expects to hand the keys over to Louth County Council this October.

Cuts the building schedule by between 25% and 30%

Kinsella also said that this method uses a third of the labour normally required and also cuts the building schedule by between 25% and 30%.

"It reduces labour by roughly a third, increases the comparative speed if one was doing it manually, by roughly three times and the overall construction programme helps housing be delivered 25-30% faster than it's current iteration. We see that getting far shorter as time goes on and as we optimise it further," he said. 

At the moment, it takes about 18 minutes for the 3D printer to lay a 50ml layer of concrete around the three-unit block on the site in Dundalk. It is hoped this time will be reduced to 12 minutes shortly.

In terms of cost, it is still comparable to concrete block construction.

"The real cost advantage is the speed at which the housing is delivered. Costs can be reduced quite significantly if you're on site for 25-30% less of the time. That's the technology margin that we're looking at at the moment", said Kinsella.

Before starting the pilot project on site in Dundalk, they built two test houses at its R&D facility in Drogheda.

He said that housing is the company's focus. 

Increases output of housing

"We see the need as housing and we need technology that can do more with less resource, and really that's what this technology is about. It increases the output of housing with the same amount of resource."

The company also said this method brings greater sustainability. Kinsella said the concrete the firm is using is the "lowest carbon embodied printed concrete globally", and that there is less waste due to "the precise and exact placement of material".

In preparation for the Grange Close scheme, HTL.tech successfully completed two two-bedroom units at its R&D facility in Drogheda, Co Louth, to demonstrate this fully compliant Integrated Modern Method of Construction (MMC) Housing Solution. This accomplishment underscores the project's feasibility and scalability.

The contract for the construction of the project was awarded to B&C Building Contractors Ltd, Carrickmacross, Co Monaghan. 

Project manager at B&C Contractors Michael McBride said his firm has been building homes for 50 years, with pre-cast concrete walls, masonry block walls and timber frame structures.

"It's great to be able to add another one into that and see where it fits into housing developments," he said of the new technology.

McBride said the 3D printer has not brought a "major change" to what it does, as it is still standard cavity wall construction. "It's just an automated process rather than a labour intensive process or off-site manufacturing process," he said.

McBride said he thinks the 3D concrete printing "definitely has a place". 

'Finished product is far superior strength wise'

"Overall the finished product is far superior strength wise to anything else we're doing so it's definitely going to take off," he said.

For those who want to be ready when it takes off, training is already being offered in the use of 3D construction printing.

The Louth Meath Education and Training Board (LMETB) has bought its own 3D concrete printer rig as part of its Advanced Manufacturing Training Centre of Excellence.

The LMETB is now working with HTL to provide this training at its research and development facility in Drogheda.

Director of further education and training at the LMETB Sadie Ward McDermott said its programme gives those working in construction access to this technology, and more than 100 people have already completed the training. 

She said that this technology is important in the need to deliver more housing and also in the context of a challenging labour market.

"In Ireland, we are in the fortunate position where we are in a very buoyant economy. We've got a very challenging labour market, and in looking at the technology, what it does also is it allows companies who are maybe challenged to get employees in, it allows the opportunity for them to continue to expand using the technology. Therefore, the labour market challenges are not as limiting and they can de-risk that challenge for themselves in using the technologies," she said.

'Augments' rather than 'replaces' aspects of construction

She said that the technology "augments" rather than "replaces" aspects of construction.

"The building of a house using a 3D construction printer such as this doesn't negate the need for the craftsman, so you will still need your electrician, you will still need the plumber to do those second fixes".

"But what this does, the scale and the speed at which you can build is significantly increased. And that, in a market where we understand there is a significant requirement to build and build at greater speed than we can currently do, this is definitely a technology we feel would be advantageous in the Irish market," she said.

Joan Martin, chief executive at Louth County Council, said: “Louth County Council is proud to collaborate with LMETB, Harcourt Technologies Ltd (HTL.tech), and Roadstone Ltd to deliver what is a very significant pilot project at Grange Close, Dundalk.

"The provision of high quality and sustainable social housing is a core objective of Louth County Council, and this project is a significant example of the use of innovative technologies and organisational collaboration in the delivery of new homes.”

Kinsella added: "Co Louth is at the forefront of innovative technology aimed at offering a solution to Ireland's housing shortage, and having grown up in the region, I am immensely proud. This endeavour highlights Louth County Council's progressive stance towards meeting housing needs and its dedication to promoting sustainable solutions.

"The transformative potential of this technology is very exciting, offering a viable solution to help address our housing challenges. We're excited to start the Grange Close project and work with our development partners to create real change."

The housing units will use 3D printing technology and prefabricated construction components, including windows, doors, flooring, and roofing.

Combining MMC component providers within the digital construction workflow of 3DCP will ensure the precise integration of prefabricated elements, expediting assembly while guaranteeing consistency. This collaboration will streamline construction processes, enhance efficiency, and boost housing production capacity.

It is intended that the Grange Close scheme showcase the use of the regulatory-compliant 3DCP technology. Compared to traditional methods, the aim is to achieve three times faster superstructure program delivery and a 25% reduction in overall project timelines. This is the first social housing project in the world to integrate 3D construction printing and ready-mix concrete while using the lowest embodied carbon mix to save 278 kg CO2e/m³ in conjunction with their building materials partner, Roadstone. 

Test houses are seen completed at HTL's R&D facility in Drogheda.

Committed to driving innovation and sustainability

"Roadstone is a solutions-focused business committed to driving innovation and sustainability," said Patrick Diviney, Roadstone, commercial manager. "We are delighted to partner with Harcourt Technologies Ltd to offer this future-based approach to construction. Integrating new technology and traditional building materials offers a new era of efficiency and carbon reduction – working towards a sustainable future.

"Collaboration between Roadstone technical staff and the team at HTL, combined with access to our industry-leading R&D laboratory, has facilitated the development of bespoke RMC designs coupled with an efficient and high-tech modern method of construction."

The 3D construction housing project is built upon HTL.tech's use of COBOD International A/S 3D construction printing technology in collaboration with Roadstone. This collaboration underscores a shared commitment to innovation and sustainability within the construction industry and signals the beginning of the technology's scalability for housing delivery in Ireland.

Louth County Council, LMETB, HTL.tech and Roadstone are committed to advancing this pioneering initiative. This project lays a path for future innovation and collaboration within the construction industry in relation to the production of high-quality, sustainable, and efficient housing in response to the ongoing housing demand.