Belinda Carr Debunks the 3D-Printed Home Fallacy

Is this a solution in search of a problem, or is it getting interesting?

COBOD 3D printer
COBOD 3d printing at work.


Belinda Carr is a YouTube creator that makes content on building science on "the latest products and technology disrupting the construction industry." With a Masters in Architecture and experience in project management, she often pokes holes in some of those architectural memes that have become so popular. Her video, "7 Reasons Why Shipping Containers Are a SCAM" has 9.1 million views and 24,011 comments, many of which are abusive, misogynistic, sexist, and awful. She kept going, doing a response to the questions, saying much of the same things I have on Treehugger, except old white males like myself don't get treated so awfully.

These "archimemes" take on a life of their own. It doesn't matter if you are an architect or helped design buildings out of shipping containers 50 years ago, as I did—you are still an idiot.

Another archimeme Carr takes on is 3D-printed housing. Carr was recently a guest on the Passive House Accelerator, discussing the truth about 3D-printed homes. Here, again, I felt right at home. She even uses a phrase that is in one of our titles: "Why 3D Printed Homes Are a Solution Looking For a Problem." For this, I have been called "stupidly conservative."

But Carr articulates many of the same problems I complain about in posts like "Nobody Has 3D Printed a House in 24 hours. Since she did her first video, she has become more positive and optimistic about the subject, but Carr still goes for the jugular:

"We're just going to go over some of the common myths about 3D concrete printing. Things that I've heard a lot of people regurgitate because of articles that would release... Promoting these myths and hyperbole. And one of them was 3D printed homes can be built for less than $4,000. That's not true."
ICON House


We picked that one up, a pitch by ICON with its first house, in our post "Affordable House Can Be 3D-Printed for $ 4,000 in 24 Hours." But as we noted subsequently, there is more to a house than just the walls. Carr gets this too, noting:

"A house or a home has so many other components to it, whether it's electrical, plumbing, insulation, roofing, pouring the slab before you start printing. There is just so much more to it than just printing walls. If you ever read claims of printing in 24 hours, they are ignoring the setup time to set up this printer, to calibrate the printer once it's on site, and then even the curing time, because obviously, you can't print all these layers at once. You have to print a couple of layers, wait for them to cure, too harden, and then they're stable enough to print the next couple of layers. Printing time is not the same as the construction deck to build the homes. They're two completely different things, and companies should be open about that distinction."

Another claim is that 3D printing can solve the problem of homelessness. But Carr notes it is not so simple.

"I feel that's arrogance and it's oversimplifying an extremely complex problem. In architecture school too, where we have all these issues that we are presented with like, "Come up with the solution that can solve the housing crisis, or the homelessness crisis,' and a building itself is not going to do that. We need several other industries involved in this extremely complex and extremely disturbing problem. Whether it's psychiatrists or people assisting in job searches or in healthcare. There's so many issues rather than just putting a roof over your head."

Or, as I have said, "It is the ultimate Silicon Valley high tech solution, but housing has never been a technological problem: it is economic and social."

Carr continues by asking whether 3D printing is sustainable. It is claimed that it is, because there is not much waste; you only print out what you need. Carr writes, "That's a form of sustainability, but concrete in itself is not the most sustainable material. I love the solidity of concrete and I think it's wonderful material. It's helped us tame nature in a lot of ways, but its carbon footprint is a major concern."

However, after she did her first video, Carr was contacted by some of the companies involved. She met the ICON people, stayed in one of their houses, and was impressed. She said: "The moment you walk in it, it's just very polished and super quiet because, it's basically a concrete home, and they just take a lot of care in how the home is presented to people and I really appreciated that."

Inside ICON House
A 2,000-square-foot ICON home in progress in Austin, Texas.

Regan Morton

Here, we part company. I have complained that most of the 3D printers used concrete goop and we are trying to get away from concrete, and with a few exceptions, they could just do walls, really just a small part of a completed house. So, why bother? Both apply here.

This is not a 3D-printed concrete home; it is a wood frame home with its ground floor walls 3D-printed out of cement. The rest of it is a traditional wooden box sitting on top. Given that a framing crew could have built those walls out of wood in a couple of hours, what is the gain here, bringing in a separate trade, a fancy printer, just to do the ground floor exterior walls? Given that everything else in the house—the wiring, plumbing, roofing, foundations, etc.—is conventional, what proportion of the substance and value of this house is actually 3D-printed? What problem is solved?

exterior of house showing roof
ICON house in Austin, Texas.

Casey Dunn

ICON got back in my good books with their stunning House Zero designed by Lake|Flato, but again, it is just printing out the walls. I noted: "I have wondered if ICON's system can truly be called 3D because it is really an extrusion of a 2D plan into the third dimension."

I have written how I am not a total skeptic about 3D-printed houses and I believe there is a place for them (on the moon, for example). But Carr reminded me during the discussion that there are some interesting and worthwhile things happening here on Earth. She said, "Hyperion Robotics in Finland, they are, I think, a bunch of really, really smart engineers that have chosen to use a 3D concrete printer for engineering applications rather than architecture, that they have no interest in printing homes. I think they're printing bases for electrical towers or, I think footings for buildings or something like that. They're trying to use, and I believe one of their proposals used 75% less concrete for a footing."

The 3D Wasp House. Mario Cucinella Architects

She also, like me, admires the 3D Wasp system, where architect Mario Cucinella built an entire gorgeous building, including the roof, out of clay. I described it as "the most interesting 3D printed house concept we have seen yet."

Carr concludes that "we talked about the myths about 3D concrete printing, but this is such a new industry and there is so much research and innovation going on, it is an extremely exciting industry to be in."

Perhaps Carr is right. Perhaps I shouldn't be so stupidly conservative. As I concluded after seeing another interesting Italian design: "I have called 3D-printed houses the new shipping container house, a fad, a dumb idea, a solution in search of a problem. But with new machines, new mortars, and talented architects, perhaps this is all getting interesting."