10-15 years ago prefab homes were going to be the new thing, built efficiently in a factory then inexpensively and quickly assembled on site. And yet the total cost was almost always more than standard construction. Now it's 3-D printing. Ok, sure.
Difference is that the prefabricated construction techniques actually do tackle the entire build, and allow time consuming bits like foundations, roofs, plumbing/wiring and kitchen/bathroom fitting to be done in parallel (it just doesn't scale particularly well to individual homes built on lots where on-site time isn't a major issue; city centre hotels are a different story)
This just tackles the low rise exterior wall bit - usually a fairly quick and uncomplicated bit of the build with a lot of options - and more specifically replaces the quick and basic technique of pouring concrete between wooden boards with highly sophisticated machinery and tight tolerances. The one thing it does do very well is permit complex shapes that basic poured concrete casting or off-the-shelf cladding can't achieve - but sculpted forms in concrete is a pretty small niche in residential construction, and much more of a high end architect request than a baseline for building homes efficiently
Yeah, this technique definitely has a techno-cool factor, but it just isn’t replacing particularly difficult or time consuming portions of a build. It appears that if you want 2 stories the second story is stick-framed (as are the interior walls) so you can’t even avoid hiring framers entirely.
Having a new house built now and of the roughly 7 month schedule, framing, sheathing and wrapping with WRB is less than 2 weeks.
For the most part, those cost differences are due to US trucking being expensive and international shipping relatively cheap rather than anything specific to the modular construction. The same material (actually more due to waste) has to be transported to the site if you use different methods of construction. The need to fit on the back of a truck imposes an upper limit on the smallest dimension of a room if they're shipped as full rooms and not flat packed wall units, of course, but that's unlikely to be an issue for student apartments in Cali.
But the structure is the easy part. The hard part is literally everything else, and 3d printing concrete doesn't make that any easier from what I've heard.
The home 3d-printing machinery (e.g. Vulcan of ICON: https://www.iconbuild.com/vulcan ) is huge, it's a 10,000 lbs machine that requires specialized equipment to transport, specially trained staff to operate and maintain, and in test runs so far they're only printing the first floor, so all homes built are a hybrid of 3d-printed concrete structures with wooden ceilngs and second-floors, and concrete floors made the conventional way.
If you're thinking of making a conventional home, it'll be considerably cheaper making it the conventional way, 3d-printing it will no doubt be substantially more expensive.
But the reason why one would want 3d-printed homes (i.e. just the first-floor wall structure) is because of some interesting possibilities: extremely high energy efficiency without effort, unique designs that can whether extreme climate events, air quality (concrete doesn't invite mold like wooden structures do!) and other nifty things like futuristic and organic designs, curved and sloped walls.
I'm pleasantly surprised by what ICON has accomplished. I see potential for this to become valuable when making bespoke energy-efficient and densely-packed neighborhoods. And I think after more ideas and workflows emerge to wrap up and finish a full house, it might become a commonplace technique for developers to make use of.
Curved and sloped walls sound cool until one realizes that everything that one would want to put on those walls is meant for flat ones. TVs are flat, couches and cabinets are rectangular, etc.
Poorly insulated walls lead to water condensing in the corners. In fact, concrete buildings are more prone mold during cold winters than anything that is properly insulated.
