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Comment by cheschire | Hacker News Reader

I hope 3D printing homes will take off now that lumber prices are so ridiculous. The sudden cost increases in other materials will now hopefully give 3d printing space to achieve economies of scale.

Imagine homes that are printed with a 20 year life expectancy. Especially in America where I don't know many families that remain in the same house for 20 years. We could start going to the Japanese model of razing the house as an expected part of the land purchase. This has the added benefit of making it significantly easier to keep houses up to modern code.

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I really don't like America's throwaway culture. Leastwise for homes. It is wasteful and short-sighted. We should be thinking of how to maintain and preserve the existing homes we do have. There are thousands of homes in the US that are over 200 years old. What jewels they are. I don't mean to be rude, but I really hope your idea does not catch on, especially after seeing half of my childhood town's cornfields get torn up for cookie-cutter subdivisions over the past few decades. Homes are no longer built by the people that will live in them. They're built by development corporations. Just imagine that development corporation, what was cranking out identical clones for the past decade now literally printing them out from a robot factory, and all of them going to fall down in 20 years. Mmm, that yummy profit, though. There's tornados here, by the way.

I mean, this is the same technology used to make....... bricks.

We used to make homes out of bricks, and we could do that again, now that lumber is expensive.

> We used to make homes out of bricks, and we could do that again

Not in areas with earthquake building codes.

1. That’s not strictly true. Masonry construction isn’t impossible in earthquake regions, but it can’t be very tall and has to be reinforced. The details depend on the jurisdiction and building code. As an example consider the vast number of cinderblock commercial and light industrial buildings (mostly 1-2 story) throughout California.

2. Earthquake prone areas are a minority of the surface area of the earth. Suppose just the non-earthquake prone areas shifted significantly toward local masonry as a building material, that should still greatly reduce supply pressure for lumber.

Are you suggesting that this whole building be set on fire? Because unfired bricks are crap.

Something like that could actually work. Bricks were often assembled into the kiln that would fire them. If you could figure out a way to efficiently bake these structures they would be incredibly durable and would require no additives since you would want to use all clay.

more adobe than brick, then

The interesting question would be to know if the mix of raw earth + additives necessary for 3D printing, can be reused for a new construction after 20 years.

The raw earth used for traditional building techniques like rammed earth, can be re-used just by adding some water after razing the earth walls, as long as no cement/lime additive was initially used. This is also the Achilles heel of these traditional techniques: moisture will destroy the structure of a rammed earth wall when not appropriately protected with a large roof + above the ground foundation to avoid capillary rise.

We don't need a new construction methodology to fix a materials problem. A specialized construction methodology makes the problem worse, because they often require very specific materials.

My 3D printer is compatible with ~5 very specific types of plastic. Traditional construction can be done with plastics, metals, masonry, wood, composites, and many others.

I didn't imply that 3d printing should fix the materials problem, I simply hope that the materials problem gives 3d printed housing enough room financially to achieve economies of scale to bring the prices down for those situations where 3d printed houses are specifically relevant.

Consider as one example low income areas that are filled with housing built in the 40's and 50's which can now be razed and replaced without inadvertently causing gentrification.

Unless those houses are irretrievably dilapidated and neglected, why raze them? Seems more sustainable to re-use something that's already there.

Agree that some areas like Detroit that have houses that have been abandonded, scavanged, vandalized, and left open to the elements for years are in most cases not salvagable.

It would certainly fill a niche if they can create a system that only requires 2 guys and a truck to deliver and set up. Even better if they don’t have to be on site while it’s printing so they can do multiple jobs at once.

This is pretty much the idea behind prefab/modular construction, isn't it?

I think that's the first time I've heard of someone considering the Japanese home ownership model aspirational. Isn't that also where the 100 year mortgage idea started?

I'd rather see that we built really solid houses that are fundamentally designed for ease of renovation, rather than routinely raze and rebuild from scratch. Code improves over time but not on a timescale that makes 20-year rebuilds sensible.

Unfortunately a lot of the rebuilds happens because of dramatic code changes. Houses built just 5 years ago will often be illegal to build again. Only way to bring it up to code is total remodel or worse tear down.

Your post is not how things work, already built homes are grandfathered in. There are still houses with knob and tube wiring, balloon framed houses, all sorts of things that aren’t allowed any more by building code.

If a Toll Brothers/(any builder) has generic plan house blueprints that need to be updated to include the new code changes, they pay an architect to change the drawings to include the new code requirements, and then continue building that design of house.

This is an extremely exaggerated take. Again, the building codes do not upgrade on that fast of a time scale and even if a house is technically not up to code, they are grandfathered in based on the time they were built. A house that was built 10, 20, even 30 years ago, is still totally fine to live in, even if not up to the most current codes.

Is anyone trying to make homes out of plastic lumber? Like the material from the Trex decks and Polywood tables. My understand is that those are 100% recycled materials, solid, and a decent alternative to wood.

A friend has a deck made of Trex (or some similar brand) and it's disintegrating. Needs to be completely rebuilt. The stuff doesn't hold up outdoors. Might be OK for structural framing that is kept dry under a roof and inside walls, if it compares to similar sized wood lumber in terms of strength in both shear and compression.

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