CNC House Construction Team

A CNC fabricated home built by Rural Office for Architecture

1. Digital Printing

It goes without saying that the word ‘printing’ is synonymous with paper, and thus the concept of designing an item using CAD software or the like and then ‘printing’ it in a material such as wood or concrete, rather makes the mind boggle. But digital printing will play a big role in off-site construction.

There are two areas of digital printing which are likely to be with us for the foreseeable future: CNC machining or milling, and 3D printing. The best way to differentiate between the two is perhaps by describing CNC fabrication as a process of subtracting — it cuts a material into desired components or shapes. 3D printing sees materials added to, to create the desired outcome.

One such example of the former is the prototype developed by architect Niall Maxwell of Rural Office for Architecture. Another is WikiHouse: an open source building system.

“In tangible terms WikiHouse is a series of pre-drawn details, proven to work, that can be used by anyone to design their own home,” explains Homebuilding Editor Jason Orme, who recently interviewed the powerhouse and cofounder behind WikiHouse, Alastair Parvin. “The ‘building pieces’ can then be manufactured by a CNC machine and built on site by the owner. Not only does it open up the world of architecture, but it makes the scary world of building houses about as possible as a fairly complicated IKEA kit.”

In the UK, materials ranging from glass, steel and concrete have all been experimented with. Not only will the items with which we furnish our homes by produced in this way, but even our houses could be ‘printed’. In fact, in July this year Chinese construction company Zhuoda Group erected a house constructed of six 3D printed modules — in just three hours. 

Could CNC Fabrication Provide a Model for Low-Cost Housing?

Rural Office for Architecture CNC home interiors

“This project started life as a response to other commercial and open source projects experimenting with plywood and CNC fabrication techniques,” says architect Niall Maxwell of Rural Office for Architecture. “Our ambition was to develop a prototype for a self-assembly plywood studio kit, made using CNC fabrication techniques, for use by home workers and those involved in creative practice. The building should be easily assembled by two people, affordable, thermally efficient and comply with Permitted Development.

“The system is designed from plywood sheets alone creating simple modular repetitive structural panels for walls, floors and roof. It requires no additional structural support above ground, and is designed with no structural redundancy; the plywood acting as structure, building envelope and internal finish. This is the key difference between our prototype system and that of others which use a more traditional structural hierarchy.

“So think of it as the building equivalent of flat-pack furniture, but with the added benefits of future extension, alteration or relocation. The materials are chosen for their environmental credentials and the whole building has the ability to be recycled.

“We are currently developing a further prototype and exploring ways in which the system can be used to develop low-cost housing,” concludes Niall Maxwell.

2. Off-Site Construction

Of course, key to building a home that is airtight and well insulated is accuracy and attention to detail at both the design stage and during the build; on-site construction can present a particular challenge here. “The skills gap in this area is a big issue,” says Gwyn Roberts.

Could increasing dependence on prefabrication – off-site, factory-controlled construction – be the solution for our self builds in the coming years?

Some modern prefab solutions have been with us for a good number of years; SIPs (structural insulated panels) for one. But more methods are likely to be developed, with other existing systems gaining popularity. Architect Paul Testa sees timber as key to the future of prefabrication, but masonry is also moving with the times.

“Wienerberger [the world’s largest brick manufacturer] do have systems which are built off-site in Europe,” explains Gwyn Roberts.

There are challenges too in this market. “As soon as you build a factory you need a stable housing market; if the market dips you cannot sustain this type of construction,” warns Roberts.

3. Prefabricated Timber Homes

Paul TestaPaul Testa

Architect Paul is founder of Sheffield-based Paul Testa Architecture and specialises in sustainable design

“Fabrication technology is improving and the increasing skills gap is well documented. This will push a growth in methods of construction that allow prefabrication; building systems will become more prevalent. This will reduce standardisation, allowing self builders to have an input in the design of their home as the supply chain distance between buyer and manufacturer will shorten, along with the time taken to deliver the end product. Customisation, as with buying a new car, will become the norm.

“As our natural resources continue to decline and consumer awareness of this issue grows, mass timber construction (cross laminated timber, Brettstapel, etc.) will also shift into the mainstream. Ideal for prefabrication, it will encourage increased forestry and the locking in of huge amounts of atmospheric carbon into the structure of our buildings. It will become a necessity that the construction of our homes actively reduces global carbon rather than adding to it.

“The general trend of rising construction costs will continue, making it more important that each building element does more than one thing. We will see the mass timber structures also being exposed as internal surfaces, leading us away from fragile plastered interiors and towards warm, robust finishes.

“We will transition through a period of smart homes before we realise that additional technology only complicates things and doesn’t improve the way we live. Fabric-first approaches will dominate, delivering comfort and performance through passive systems that don’t require a smart phone or a good WIFI signal to work.

“In short, my 25-year prediction is for a growth in simple, customisable, prefabricated timber homes that deliver warm, robust spaces with exceptional comfort, low running costs and the elimination of the damp and cold defects that plague many of our new builds today.”

Read Claire’s blog on home technology of the future here

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