Why 3D Printing Buildings Leads to Problems

You know what a bad idea is? A bad idea is pouring concrete without any reinforcing. Now that's a bad idea! Even some chicken wire in the mix makes concrete so much stronger. Take it from a guy that's jackhammered up more than his fair share of concrete. You want steel reinforcing in your concrete. That fibermesh is horse crap. Know what I'm not seeing in these printed houses? Reinforcing.

I've worked closely with a leading concrete 3D printing company for several years now, so I hope my insight into the actual construction process provides some perspective. First, one clarification: There is no gravel aggregate in 3D printing concrete. It is only sand. You're right that the vertical integration is very strong in this industry, but there is already internal pressure to break that up. I expect in 10 years or so, you'll see more open-access tools available to architects and construction companies alike. I can't be too specific and honor my non-disclosure agreements, but there is recognition that the ability for architects to play with shape is very limited for now, which also limits the primary advantage of concrete 3D printing over other methods: complex shapes cost the same as simple ones. The primary reasons IMO for the vertical integration is 1) that there has been a high learning curve for the industry and 2) the business case relies on minimizing labor costs and the strategies for dealing with that are still being prototyped. Normally trivial things like laying foundations, running plumbing, tying roof timbers into the frame, and lintels as you mentioned, are difficult for concrete 3D printed construction. It's only in the last year or so that acceptable, repeatable solutions have been identified for most of these and are finding their way into standard design practices. But even then, there are still maybe 5 or 10 years more of on-the-ground construction needed to establish best practice. It's not too different from the way building materials and building science radically changed in the 1980's, leading to a decade of extremely poorly built houses prone to water damage and short lifespans. It wasn't until maybe 20 years after that best practices for high-quality construction had been standardized. I would push back on the lack of repairability, though. This has always been an issue with concrete construction, and it's likely to become increasingly common for plaster or stucco finishes to be applied to internal walls, allowing for intrusive renovations to be reintegrated. Structural stability is not likely to be an issue since all walls have reinforcement every half meter anyway and often exceed building strength standards by an order of magnitude. Further, virtually all concrete 3D printing for now is slab-on-grade construction, which already has the same repairability issues you mention but is already widely adopted and has best practices for dealing with things like electrical and plumbing repair. I would also point out that the timber frame construction that we love so much is largely an anomaly unique to the U.S. where wood is abundant and cheap. Concrete 3D printed homes have the (so far unrealized) potential of being many decades or centuries more durable than frame buildings, which will change the design requirements that often contribute to design choices that later need renovations and repairs. I would also push back on the criticism of how windows and doors are seated in the concrete homes. I don't doubt that many early concrete 3D printed homes were sealed with silicone only, but 1) the gap between windows and walls is already standard in frame construction and addressed with shims, spray foam, and trim and 2) the 3D printing companies have already started to adopt the same building techniques used by frame construction. Echoing much of what you said, IMO concrete 3D printing has a high potential for unique design that won't be unlocked until architects are given freer access to the tools and pre-fab construction is a necessary companion to this industry, but there is still a lot of building science that is being worked out. There are already some serious advantges, such as all walls having a native R40 insulation rating, but these will be tempered by the inherent limitations. I don't expect to see a rapid adoption of 3D printed construction for another 5 or 10 years and for the U.S. market share to cap around 20% and primarily remain in the residential and light commercial construction spaces. I also think that the current bare-wall aesthetic will fall out of favor out in that timeframe since it will prove difficult to clean. I also expect that environmental costs will remain high as long as cement production relies on fossil fuels and concrete aggregate relies on mined sand. I also expect that a future use case for heavy construction is using 3D printing to create forms for much thicker concrete constructions, particularly for foundations, buttresses, and pillars, such as you see in airport construction. Anyway, thanks for the video, and all the best!

While I find 3d printed houses fascinating, it's kind of annoying to see it billed as a way to fight the affordability crisis as if the cause is the cost of construction, rather than an economic issue. The price of housing is artificially inflated by external economic pressures, such as houses not being listed to drive up the price of other houses due to a perceived lack of availability

The most expensive part of a house is not the material cost of a house but the land that it sits on. A burnt out abandoned house in California was sold for $1 million.

We already have quick and reliable building process, it is called "prefabricated elements"

I do not understand 3D printing houses. Wouldn’t pre-fab construction be better looking, more efficient and environmental?

I have always had a problem with the hype around 3d printed structures, especially residential structures, especially in the US. For a 3d printed house you still need a poured foundation, you still need interior finishing, you still need a roof, you still need MEP, the list goes on and on. You still need to do the rest of the house. What does 3d printing automate away? the framing and sheathing - because to be clear - the vast majority of houses are wood framed, and will continue to be. Now, what is the absolute fastest part of building a wood framed house? the framing and sheathing. 3d printing replaces the fast, easy, low skill part of home construction with something marginally faster if at all, extremely complicated, unforgiving, and requiring highly skilled workers if not engineers on site. For home construction, 3d printing is silly

Hooray for automating the least complicated, least expensive, most reliable part of the construction process! You did it, Tech Bros!

Unreinforced concrete is hell for seismic. This would never be approved in places like california, where mass production of housing is most needed.

You missed a bigger issue, building codes and inspectors. Being one of the earlier 3D concrete printer developers our biggest issue was the building inspectors here in the US. Good video.

I don't know about the who country, but put here the permiting, zoning, and land costs are what's making housing unafordable. Once you got the land and permission to build, the rest is relitivly cheap and straightforward.

2:42 You can, it's called flat arch. A somewhat forgotten technique that was very common in 19th and early 20th century. It works for spans that are 4 feet or less but it's still the majority of windows and doorways. Or you can, you know, span everything with a segmental arch like we had been doing for the past 2000 years.

I used to work as an engineer for a major 3D printing construction company and this analysis is quite accurate. 3D printed construction is a nail looking for a hammer and will never be able to reduce cost or build time of single family homes. The printed structural elements of a home only equate to ~20% of the total cost of house so in order to reduce the cost of a house by 10% printing will need to be able to halve the cost of stick framing which is impossible. And not to mention the gigantic CO2 footprint that is associated with the production of cement.

We could make a bunch of these parts like walls in factories but we made it illegal to put modular homes in 90% of America

From fairly limited experience (being involved in building five concrete brick houses/ cottages), one thing that has never made sense to me about 3D printed buildings is that in terms of cost and construction time, the walls and roof aren't such a big deal. What costs the money (and time) is the finishes and fittings, which don't seem to feature in the design software. Maybe this is just so for some places, and in others, the cost of the walls is the limiting factor. (Else, if you build your cheap walls big, you just have to spend more on expensive fittings that the walls are made to protect.) Also, the little crevices inside are not going to make for nice walls. You still need to plaster those (or cover them with drywall). On the outside, all they're going to do is provide a nice substrate for mosses and lichens - which could be great if they weren't quite likely structural hazards, long term).

This is what's described as ivory tower thinking. Most college graduates and engineers have no hand-on field experience. Talk to me when you build your own house.

One of my jobs as a welder was to inspect and correct the product of our robot welder, and I can say it was not a great welder. It had limited use as most of our weldments were not repetitive enough to justify using a robot. I only got about 5 to 8 hours of work a week from the robot. That included inspecting the welds and correcting about 10% of the finished parts. A lot of the errors were for parts that were out of tolerance, and the tolerance was pretty high on these things, ± 1/4" when most of the hand welded stuff was between ± 1/8" and ± 1/16"

Good god that transition to the sponsor segment was smoother than butter on ice

Imagine waiting and waiting for your dream house to be built, and you end up with a big rendering error intead

There's a reason we don't just pour concrete and call it a day already.