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Old 07-19-2017, 10:53 PM
SenorBeef SenorBeef is online now
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Have construction techniques for houses changed dramatically in recent decades?

It seems to me like we should've come up with some efficient way to build houses by now, like assembling pre-fabbed pieces or something, but from a casual glance it seems like houses are still built like they were 50 years ago. Guys show up, nail some wood, electricians show up and run some wires, etc. A lot of slow, manual work.

But I don't know what they're doing in detail, maybe it's surprisingly efficient.

What advances in home construction have there been in the last, say, 50 years?
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Old 07-19-2017, 11:36 PM
Whack-a-Mole Whack-a-Mole is offline
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- There are 3D printed houses: https://www.youtube.com/watch?v=xktwDfasPGQ
- There are 3D printed pre-fab houses: https://www.youtube.com/watch?v=3R1CBFBxuew
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Old 07-19-2017, 11:39 PM
gogogophers gogogophers is offline
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Prefab is light-years advanced from 50 years ago. "Stick' built, not so much. However,with the acceptance of air/paslode nailers, pex tubing, prefab joists, etc., and the myriad of power equipment available now, construction work is more efficient (and not quite as brutal) as it once was.
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Old 07-19-2017, 11:48 PM
gogogophers gogogophers is offline
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- There are 3D printed houses: https://www.youtube.com/watch?v=xktwDfasPGQ
- There are 3D printed pre-fab houses: https://www.youtube.com/watch?v=3R1CBFBxuew
Interesting concepts, but not practical... Yet.
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Old 07-20-2017, 12:21 AM
FluffyBob FluffyBob is offline
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Wood frame construction has changed significantly with engineered wood. Floors are all engineered joists that allow greater spans and spacing. Laminated Veneer Lumber beams are not only stronger, longer but also consistent in sizing compared to dimensional lumber. I know a lot of people seem top think OSB is crap compared to plywood but for sheathing it is superior in dimensional stability, uniformity and strength.

Plenty of wood frame construction is prefab; walls are built at a yard and delivered to the jobsite as a package. This is mostly used for multifamily such as townhouse construction.

Framing crews use booms to lift materials, place walls, and as lifts to reach difficult areas and install windows. Roofs are all truss rather than stick frame and go up fast. When space allows (frankly most new development sites), the roof is built on the ground in manageable sections and then lifted by crane on to the house.

Insulation, envelope management, electrical, HVAC and are all vastly improved from 50 years ago, and there are new products and materials being introduced all the time.

And commercial construction - well just look at the speed a light steel frame building can go up. There is no comparison cinder block masonry construction.
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Old 07-20-2017, 04:57 AM
bob++ bob++ is online now
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The restraints are probably due to traditional minded builders and finance companies, together with market lag. Prefabrication is the future and building new bespoke houses to a high standard in a week or two, will soon become the norm. All you need is a suitable plot and planning permission.

Watch this https://www.youtube.com/watch?v=inyjfMkq_VA
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Old 07-20-2017, 05:04 AM
engineer_comp_geek engineer_comp_geek is online now
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When they built houses around here about ten years ago, a lot of stuff was pre-fabbed.The foundation was built pretty much traditionally. I'm not sure how much of the roof was pre-fabbed, but once the foundation was done, the next time you'd see the house it would have the roof complete, sitting directly on the foundation, with stacks of walls (2x4 framing, no drywall or anything) nearby. The next day, you'd come by and the roof would be lifted and all of the walls would be put in place. The end result looked like a normal stick-built house. Then they would add insulation and the home exterior just like old-fashioned construction.
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Old 07-20-2017, 07:15 AM
Joey P Joey P is offline
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When they built houses around here about ten years ago, a lot of stuff was pre-fabbed.The foundation was built pretty much traditionally.
Did they pour it or is it block? I don't know when the transistion was made, or if there really ever was one. But my house was built around '97 and has a poured foundation and I thought that was somewhat (for the age) new as housed going back far enough were all block. Something I see now sometimes on is that the forms they use are made of styrofoam and left in place. Even faster for builders and extra R value for the homeowner.
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Old 07-20-2017, 07:34 AM
md2000 md2000 is offline
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The big difference I see in the construction in my area - the pre-fab roof trusses; plus as mentioned above, almost everything is OSB not plywood. A lot of the plumbing is PEX (?) plastic pipe with crimped rings over the joints. Certainly faster and requires less skill than soldering copper - and safer. PVC for drain pipe has been around for a long time.

Another new trend is spray-foam insulation; less labour intensive, seals better. spray it on, when hardened, saw off whatever protrudes beyond the studs. Airtight, no need to cut fibreglass pieces to fit and to fit around wires and piping.

Pre-fab windows have been a thing for years; nowadays they mostly seem to be PVC so no need for fine trim painting.

Last edited by md2000; 07-20-2017 at 07:35 AM.
  #10  
Old 07-20-2017, 07:50 AM
friedo friedo is offline
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Did they pour it or is it block? I don't know when the transistion was made, or if there really ever was one. But my house was built around '97 and has a poured foundation and I thought that was somewhat (for the age) new as housed going back far enough were all block. Something I see now sometimes on is that the forms they use are made of styrofoam and left in place. Even faster for builders and extra R value for the homeowner.
Insulated Concrete Forms (ICFs). They go together like Legos and you pour in the concrete and leave the forms in place. Very fast way to build a foundation and makes for a nice insulated, water-tight basement.

Some builders are even using prefab concrete panels for basements now. Precision factory-cured, then trucked to the site and plopped into the hole with a crane. They have tongues and grooves to interlock. The factory curing makes for much more consistent and tighter concrete than you can get in the field.
  #11  
Old 07-20-2017, 07:51 AM
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The restraints are probably due to traditional minded builders and finance companies, together with market lag. Prefabrication is the future and building new bespoke houses to a high standard in a week or two, will soon become the norm. All you need is a suitable plot and planning permission.
Throw in the insurance companies for good measure. The traditional finance aspects have really held back innovation in home building. E.g., steel studs should have taken over by now but I haven't seen it being using in any home built in my area at all.

It's a Catch-22. They need years of data in order to make financial decisions to support something new ... which of course doesn't have years of data.
  #12  
Old 07-20-2017, 07:54 AM
DCnDC DCnDC is offline
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There's at least one company developing self-contained "unfolding" houses that expand from a space the size of a standard box trailer. I can't tell whether they've actually built one yet, I've only found a lot of CG animations. They are very slick CG animations, but still just CG.
  #13  
Old 07-20-2017, 08:41 AM
John Mace John Mace is offline
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Another new trend is spray-foam insulation; less labour intensive, seals better. spray it on, when hardened, saw off whatever protrudes beyond the studs. Airtight, no need to cut fibreglass pieces to fit and to fit around wires and piping.thing for years; nowadays they mostly seem to be PVC so no need for fine trim painting.
In CA, there was a significant change to the energy code this year requiring a significantly higher R value for insulation. That, combined with the desire for peaked ceilings, makes that type of insulation the best way to go unless you want to use 2 x 10s for the rafters.
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Old 07-20-2017, 08:58 AM
Dewey Finn Dewey Finn is offline
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Originally Posted by FluffyBob View Post
Plenty of wood frame construction is prefab; walls are built at a yard and delivered to the jobsite as a package. This is mostly used for multifamily such as townhouse construction.
Houses can be built of prefab wall panels built in a factory. Or the house can be built of prefab sections with walls, floor and ceilings already assembled. The sections are trucked to the site and then lifted by crane into place. Usually, the prefab sections are designed to be small enough that they can be transported by truck, so they're about the width of a manufactured home. But once the house is assembled, it might look nothing like a double-wide trailer. And the prefab sections can have the kitchens, bathrooms, wiring and plumbing already in place, so the whole thing can come together very quickly.

Someone tried to build a 32-story apartment house in Brooklyn using prefab modules, but it turned out to be a very expensive project and the company closed down after.
  #15  
Old 07-20-2017, 09:28 AM
PastTense PastTense is online now
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The restraints are probably due to traditional minded builders and finance companies, together with market lag.
There is also the problem with building codes in many areas. And it is reasonable to wait significant time before adding new technology to building codes. As an example look at the use of aluminum wiring in the 1960s:
http://definedelectric.com/aluminum-wire-retrofit/
  #16  
Old 07-20-2017, 09:42 AM
watchwolf49 watchwolf49 is offline
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[snip] ... but from a casual glance it seems like houses are still built like they were 50 years ago ... [snap]
Western Platform construction had largely replaced Balloon construction about 100 years ago ... so in that sense the OP is right ... the materials have changed some as noted in FluffyBob's excellent breakdown ...

Overall though, the OP is spot on ... except for all the bells and whistles and fancy-pants "new age" conveniences ... homes today are pretty much built the exactly same way as they were 50 years ago structurally ... foundation, floor, walls, another floor, more walls and a roof ... it works, and it works very well, no need to change ... a properly built home with decent quality materials and maintained will last a century or more ...

Pre-fab walls and engineered trusses is great for tract housing ... but if you drive through the richer neighborhoods you'll notice every house is quite different ... here really stick framing is the only option ... particularly for the complicated and unique roof framing ... and some customers do insist on the use of nails, instead of staples ...

One last comment ... in theory, marijuana can be used for OSB ... criminality is one hold-up to getting such a product to market ... as this restriction is slowly evaporating I think this will be the next big break through in materials technology ...
  #17  
Old 07-20-2017, 09:46 AM
friedo friedo is offline
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There is also the problem with building codes in many areas. And it is reasonable to wait significant time before adding new technology to building codes. As an example look at the use of aluminum wiring in the 1960s:
http://definedelectric.com/aluminum-wire-retrofit/
Polybutylene water piping was another disaster that led to all kinds of problems down the line. Code authorities are right to be cautious with new materials and techniques. Unfortunately, there's a chicken-and-egg problem there. You can't prove a new thingy is safe until you build a lot of them, but you may not be able to build them without evidence that it's safe.

So it takes a long time for new construction technologies to catch on. That's OK. Construction is one industry where being very conservative is probably a good idea.
  #18  
Old 07-20-2017, 10:57 AM
Really Not All That Bright Really Not All That Bright is offline
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What advances in home construction have there been in the last, say, 50 years?
Edison came up with a plan to build entire homes from poured concrete using a single mold. For reasons that are oddly not touched on in that article, it wasn't practical - the aggregate didn't distribute evenly in molds that big and putting the forms together on site turned out to be just as complex as actually building a house.

Nowadays, poured concrete homes are common, as friedo described; you just can't pour them all in one go.
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Old 07-20-2017, 01:41 PM
engineer_comp_geek engineer_comp_geek is online now
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Did they pour it or is it block? I don't know when the transistion was made, or if there really ever was one. But my house was built around '97 and has a poured foundation and I thought that was somewhat (for the age) new as housed going back far enough were all block. Something I see now sometimes on is that the forms they use are made of styrofoam and left in place. Even faster for builders and extra R value for the homeowner.
These were block foundations.

As I understand it, block is still used in new construction. Whether they use block or poured concrete depends on a few things.

How close they are to the concrete plant is important. A poured foundation requires a lot of concrete, and you're not going to want to mix up that much concrete on site. That means you need to be reasonably close to the concrete plant for it to be practical.

Block walls are stronger in compression, and poured walls are stronger for lateral stresses. Some architects have a preference for one or the other.

When the economy is going well and labor rates are higher, poured concrete is cheaper. When labor rates are lower, block can be cheaper.

Scheduling may make a difference. A poured foundation needs time to cure, where a block foundation is ready to go as soon as it is completed.
  #20  
Old 07-20-2017, 01:51 PM
md2000 md2000 is offline
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Edison came up with a plan to build entire homes from poured concrete using a single mold. For reasons that are oddly not touched on in that article, it wasn't practical - the aggregate didn't distribute evenly in molds that big and putting the forms together on site turned out to be just as complex as actually building a house.

Nowadays, poured concrete homes are common, as friedo described; you just can't pour them all in one go.
I have seen a few full houses (except the truss roof) built with foam concrete block forms for cement. A two story house with basement poured (one floor at a time). Support points for the (wood truss) floor joists built into the concrete. the connectors to hold the stucco mesh embedded in the concrete through the foam. A second hand comment I heard for one of these houses - incredibly quiet, a lot less outside noise.

With modern computer design techniques, it would be less work to prebuild all wall sections etc. for even a custom house in the factory, and ship them to the site. However, gyproc (drywall) is not terribly forgiving for transport as it is currently attached (screws). I imagine in a factory, gluing could be a more practical option, less likely to crack... but then, handling becomes the issue. a wall section fully drywalled both sides would be difficult to handle, especially with machinery. Then, you have to leave openings to attach it to the other walls and floor. (cutouts in the gyproc?)

Then there's the issue of electrical and plumbing - how do you connect prefab pieces? You certainly don't want junction boxes at each floor or wall joint. Some things are better done in continuous runs. (I imagine conduit and wire-pulling strings being the preferred technique.) or maybe they only drywall one side leaving access to the studs for wiring and plumbing?

I suspect prefab on this level has a way to go. Plus, it will be economical when the assembly at the factory is automated to the point where it is far less labour-intensive than onsite cut and fit. I.e. robots cut and fit and nail and glue the pieces according to computer instructions.
  #21  
Old 07-20-2017, 02:23 PM
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Pre-fab has been around for 40 years that I know of.

Quite efficient, but planning/zoning has been the problem.

I still do not like OSB, PEX scares me (I sweat copper, and that is light-years from what Daddy taught me).

I am now waiting for Google maps to resppond to a scroll request - I am back in the market for real plumbing supplies, and it seems my fav supply store has folded.

Big-Box stores are fine for cheap, large-volume stuff - if you don't mind sloppy threads, barely-legal everything.

Try finding 1 1/4" anything in plumbing - copper or steel, or any plastic.

My sis and hubby bought a townhouse in San Diego. It used a "Brand New! Plumbing of the Future".
It all had to be torn out and replaced with copper. Don't know if the litigation was ever settled.
I am quite leery of PEX just because of that.

"I'm a horse-drawn man until my dyin' day"
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Old 07-20-2017, 02:52 PM
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As I've mentioned before when this topic comes up, PEX has been around for 50 years and has about the best possible track record any building material can have.

Of course, you still have to install it correctly. But that's just as true for copper.

Last edited by friedo; 07-20-2017 at 02:52 PM.
  #23  
Old 07-20-2017, 04:09 PM
watchwolf49 watchwolf49 is offline
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How well does PEX handle physical trauma compared to sch L copper pipe?
  #24  
Old 07-20-2017, 04:35 PM
Roderick Femm Roderick Femm is offline
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This Old House did at least one series where they did a new house that was built in complete sections (custom built in a mill, as they called it) and assembled on site. It was one of the more interesting of their series to me, as being something that I could see doing myself. It seemed possible to build in a lot more quality and a lot cheaper than doing it piecemeal on-site.

I've often wondered if we could use this technique if, say, our house burned down and had to be re-built. I live in San Francisco on a 25' frontage with zero lot lines (meaning the houses are right up against each other with no or negligible space between), and on a narrow street. We'd probably have to clear the street of parking all the way to the end to get the crane in, which would certainly boost our popularity!
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Old 07-20-2017, 04:49 PM
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It's very difficult in crowded residential areas, due to the need for large equipment (cranes and such) to move the modular pieces around. It's great for new construction, though.

Last edited by friedo; 07-20-2017 at 04:49 PM.
  #26  
Old 07-20-2017, 04:52 PM
friedo friedo is offline
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How well does PEX handle physical trauma compared to sch L copper pipe?
PEX is flexible, which lessens the effect of water hammer. And because you can usually run a single piece like a wire from the manifold to the fixture, you don't need fittings inside the wall where they can leak. PEX will also tolerate freezing without bursting (to an extent) much better than copper, again owing to its flexibility.

OTOH, don't shoot a nail through it. Also, you don't want to leave it exposed to direct sunlight. If you're running exposed lines near a basement window, for example, you'll want to cover them with insulation or use copper for that section.
  #27  
Old 07-20-2017, 05:52 PM
FluffyBob FluffyBob is offline
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Yes the fear of Pex is completely misplaced, it is a great product. PolyB was complete junk and I suspect there was some palms greased during its brief adoption. PolyB is flimsy, thinner and softer than pex. In the late eighties and early nineties when it was common, (up here in Alberta anyway) building practices were at a low.

ICF has its place but there is no way it is any faster than a cribbed foundation by a good crew. It is also pain in the ass for electricians unless a frost wall is framed in front of it. The same or better insulation gains can be had with foam panels applied to a cribbed foundation before backfill.
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Old 07-20-2017, 07:05 PM
watchwolf49 watchwolf49 is offline
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Yes the fear of Pex is completely misplaced, it is a great product ... [snip]
Been doing some Googling and for the most part PEX has the same failings as copper ... poor installation and bad quality fittings ... but for about a third the price as copper ...

The one exception is rodents chewing on the PEX ... for which one plumber posted "You should get a free kitten with every 100' roll" ...

Works for me ...
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Old 07-20-2017, 07:19 PM
Weisshund Weisshund is offline
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How well does PEX handle physical trauma compared to sch L copper pipe?
You'd pretty much have to cut it.
You can bend it kink it beat it with a hammer, heat it with in reason, freeze it.

Only thing it fails to is a rat eating it, and ive seen them eat copper even
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Old 07-20-2017, 08:26 PM
watchwolf49 watchwolf49 is offline
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You'd pretty much have to cut it.
You can bend it kink it beat it with a hammer, heat it with in reason, freeze it.

Only thing it fails to is a rat eating it, and ive seen them eat copper even
Cutting is a real issue IF the piping is exposed ... and even in the wall, there's a level where PEX will fail and copper won't ... but we're talking about extremes, I see why people think it's a non-issue for normal circumstances ... just how often do regular homeowners have knife-murderers slash their wall enough to cut PEX but not copper ...

The particular installation I ripped out (with angry comments about lawsuit) was the PEX dangling in the crawl space under the floor insulation layer ... easy to catch with and arm or tool belt ... but that's "poor installation" so not a specific problem with PEX ...

I sweated copper in place and have lived happily ever since ...

=====

Note all this about PEX is just modern and better materials we build our homes out of ... the basics of indoor plumbing hasn't changed over the past 50 years ...

Last edited by watchwolf49; 07-20-2017 at 08:28 PM.
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Old 07-20-2017, 08:31 PM
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There's some pretty awesome things being done in Japan - all timber pre-cut by robots in factories, and then delivered and assembled in a matter of days.
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Old 07-20-2017, 08:47 PM
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Yeah, my PEX is clamped to the underside of joists, etc. Just because it's plastic does not mean it can swing free.
  #33  
Old 07-21-2017, 09:05 AM
Really Not All That Bright Really Not All That Bright is offline
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Our plumber says that PEX usually lasts better in places with hard water, because copper pipes tend to accumulate deposits (and ultimately wear) faster. Our neighborhood in Florida is full of houses with new-build copper pipes running through the slab, which have since been replaced by PEX run through the attic.
  #34  
Old 07-21-2017, 10:26 AM
Tom Tildrum Tom Tildrum is offline
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Originally Posted by Really Not All That Bright View Post
Edison came up with a plan to build entire homes from poured concrete using a single mold. For reasons that are oddly not touched on in that article, it wasn't practical - the aggregate didn't distribute evenly in molds that big and putting the forms together on site turned out to be just as complex as actually building a house.

Nowadays, poured concrete homes are common, as friedo described; you just can't pour them all in one go.
Oh, that kind of thing has been around for a long time.
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Old 07-21-2017, 11:06 PM
Mr Downtown Mr Downtown is offline
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Seems like there's a lot less hammering than 50 years ago, what with framing and roofing done using nail guns; and on the inside, cordless screwdrivers, Liquid Nails, and brad nailers for trim.
  #36  
Old 07-22-2017, 08:11 AM
md2000 md2000 is offline
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There's some pretty awesome things being done in Japan - all timber pre-cut by robots in factories, and then delivered and assembled in a matter of days.
That was similar to my thought - in future, you could have an automated factory like that which could pre-assemble 2x4 walls (and 2x6 exterior walls) and deliver sections 8 feet high or so to the site, where they would be assembled like a jigsaw puzzle - much as truss roofs are nowadays. It eliminates the tedious cut and fit labour. A computer controlled assembly table handling wall sections 8 to 10 feet by whatever (say, up to 16 feet long) would be similar to what is done for trusses today. You could even pre-drill the studs for electrical and plumbing. As I said earlier, you could even glue down drywall on one side (or OSB for exterior walls). The trick would be to get a complete and accurate set of plans, instead of a lot of winging it onsite as the building progresses. (i.e. for electrical, plumbing runs).

However, electrical and plumbing still need to be direct one-piece runs, since every water or electrical connection is a potential point of failure.

Lately I've noticed a lot of commercial buildings where instead of pouring a concrete floor, they haul into place pre-cast floor sections. These are hollow down the middle like a bunch of square tubes stuck together, so obviously less weight (and cheaper, less concrete).
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