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?
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.
Interesting concepts, but not practical… Yet.
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.
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 How Do They Do It?- Prefabricated Homes - YouTube
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.
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.
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.
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.
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.
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.
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.
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.
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/
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 …
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.
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.
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.
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.