Modular construction: Using Lego-like blocks to build structures of the future

Buildings don't have to be permanent — modular construction can make them modifiable and relocatable.

Modular construction

Modular construction

  • Modular construction involves building the components of a habitable structure in a factory, and then assembling those components on-site.
  • The history of modular construction stretches back centuries, and it became briefly popular in the U.S. after World War II, but it's never quite caught on.
  • Construction firms like iMod Structures, which constructs buildings that can be modified and relocated, may soon change that.

Modular construction is on the rise. Once a marginal sector focused on building affordable homes, modular construction is now building an increasing share of structures used for commerce, healthcare, and education. By 2028, the modular construction market is projected to be worth $114 billion.

What is modular construction? It's like building with Legos but on an industrial scale: standardized block-shaped modules are constructed in a factory, transported to a building site, and assembled together to form a habitable structure.

What's most striking about modular buildings isn't appearance but the speed of construction. In 2015, for example, a Chinese construction company built a 57-story glass-and-concrete skyscraper made of 2,736 rectangular modules in a record-breaking 19 days. That's three stories per day.

In addition to speed, modular construction promises to be more modifiable, more transportable, and less wasteful than traditional construction methods. The method could transform construction, which, despite being one of the world's biggest sectors, is one of the slowest growing in terms of labor productivity and digitization.

One modular construction firm aiming to bring the sector into the 21st century is iMod Structures, which builds shipping container-sized modules that can be assembled into buildings. The modules can then be disassembled to modify the existing structure or transported to a different site to build a new one.

Freethink recently visited iMod Structures to get an up-close look at its unique spin on modular construction.

Do buildings have to be permanent? | Hard Reset by Freethink

Techniques like this could help bring construction into the 21st century. But despite its futuristic and transformative appeal, modular construction is far from a new idea. In fact, the history of prefabrication — the broader category of construction to which modular belongs — goes back centuries.

Prefabrication: From 17th-century cottages to diners to skyscrapers

One of the earliest examples of prefabrication came in 1624, when a colonial American fisherman commissioned an English construction company to fabricate components of a building and ship them overseas to the fishing village of Cap Anne.

In the 17th and 18th centuries, English firms also shipped prefabricated structures — storehouses, cottages, and hospitals — to Australia, South Africa, and New Zealand. In the U.S., prefabricated homes became popular during the Gold Rush when California towns had too many people but too few houses.

In the early 20th century, mass-production made modular construction more practical and, sometimes, more popular. From 1908 to 1940, Sears sold about 70,000 kit homes across the country; some of the cheapest models started around $160. (Kit homes were like IKEA products: the manufacturer builds and precuts the parts, and the buyer assembles them.)

Still, prefabricated homes weren't particularly popular in the first half of the 20th century; homebuyers generally viewed the structures — especially the metal and experimental ones — as strange and undesirable.

Modular construction Pre fabricated house shipped via boxcarThe Aladdin Company via Wikipedia

But appearance wasn't a major concern during World War II. Facing huge demand for cheap and simple housing for soldiers in the early 1940s, the U.S. produced hundreds of thousands of Quonset huts — prefabricated, semi-cylindrical structures made of corrugated galvanized steel — which about six unskilled laborers could construct in a day.

Modular construction A Quonset hut being put in place at the 598th Engineer Base Depot in Japan, post-World War IIUS Army Corps of Engineers via Wikipedia

After the war, millions of U.S. soldiers returned home, and the nation faced a housing shortage crisis. Hundreds of companies entered the prefabricated housing market, with several receiving support from the federal government. One of the most iconic models was the enameled-steel Lustron house, which cost $7,000 to $10,000, took two weeks to assemble, and promised to "defy weather, wear, and time."

Modular construction Lustron HouseAdirondack Architectural Heritage

By 1958, roughly 10 percent of all homes in the U.S. were prefabricated. In addition to homes, the prefabrication industry also built thousands of diners throughout the 20th century, especially after World War II when owning a prefabricated diner was a decent small-business opportunity. Popular in New Jersey, the narrow diners could easily be shipped to buyers by rail.

Interior of a 1938 Sterling manufactured diner, with curved ceiling, in Wellsboro, PennsylvaniaI, Ruhrfisch via Wikipedia

Despite the post-war boom, modular construction never really caught on in most parts of the world, though many architects and builders have long been attracted to the method. Some of the reasons include consumer perception that modular homes are unattractive, technological constraints, and the high costs of researching and developing new building techniques.

These challenges can be prohibitive, especially for large-scale projects.

"Building anything over 10 stories in modular is something no one has wanted to do because you have to invest in research and development," Susi Yu, executive vice president of residential development for the Forest City Ratner Corporation, told Fast Company. "There's science behind it that you need to figure out."

But attitudes on modular buildings may be shifting.

"Today, modular construction is experiencing a new wave of attention and investment, and several factors suggest it may have renewed staying power," noted a 2019 report from the consulting firm McKinsey & Company. "The maturing of digital tools has radically changed the modular-construction proposition — for instance, by facilitating the design of modules and optimizing delivery logistics. Consumer perceptions of prefab housing are beginning to change, particularly as new, more varied material choices improve the visual appeal of prefab buildings."

The report goes on: "Perhaps most important, we see a change in mind-set among construction-sector CEOs, as many leaders see technology-based disruptors entering the scene — and realizing it may be time to reposition themselves."

In recent decades, construction firms around the world have built all kinds of modular buildings, including modular skyscrapers in the U.K., U.S., and China; containerized homes in Mexico; and classrooms in rural South Africa.

"In many countries, modular construction is still very much an outlier," McKinsey noted. "But there are strong signs of what could be a genuine broad-scale disruption in the making. It is already drawing in new competitors — and it will most likely create new winners and losers across the entire construction ecosystem."

The benefits of modular construction

Modular construction has the potential to deliver $22 billion in annual savings to U.S. and European markets, mainly because of the inherent benefits of building components in a controlled factory setting. The Modular Building Institute lists a few examples:

  • Shorter construction schedule. Because construction of modular buildings can occur simultaneously with the site and foundation work, projects can be completed 30 percent to 50 percent sooner than traditional construction.
  • Elimination of weather delays. 60 to 90 percent of the construction is completed inside a factory, which mitigates the risk of weather delays. Buildings are occupied sooner, creating a faster return on investment.
  • Improved air quality. Because the modular structure is substantially completed in a factory controlled setting using dry materials, there's virtually no potential for high levels of moisture (which can cause mold growth) to get trapped in the new construction.
  • Less material waste. When building in a factory, waste is eliminated by recycling materials, controlling inventory, and protecting building materials.
  • Safer construction. The indoor construction environment reduces the risks of accidents and related liabilities for workers.

But perhaps the biggest benefit of modular construction is relocatability and modifiability.

Future-proofing buildings and cities

Buildings are hard to modify and practically impossible to move. That's a problem for many organizations, including the Los Angeles Unified School District. The district currently maintains thousands of decades-old trailers it built to accommodate a fast-growing student population.

Seeking to replace those trailers with structures, the district partnered with iMod Structures to build "future proof" modular classrooms that can be reconfigured and relocated, depending on fluctuating enrollment levels.

"If you have one of our classrooms in a particular location and 5, 10, or 20 years later, you need them across town at another campus within the school district, you simply disassemble, relocate, and reassemble them where they are needed," Craig Severance, Principal with iMod Structures, said in a statement. "And it can be done within a few days, minimizing school [downtime] and disruption of our children's education."

Modular construction iMod Structures classroomiMod Structures

Founded in 2009 by former real estate investors John Diserens and Craig Severance, iMod Structures takes a hyper-efficient approach to modular construction. Instead of making many types of prefabricated components, the firm makes only one standardized block-shaped frame, each roughly the size of a shipping container. The firm builds the frames in factories and then outfits them with walls, windows, and other custom features the client wants.

Because the frames have the dimensions of a standard shipping container, they can be easily transported to the building site by truck or rail. On site, the frames are connected together or stacked on top of each other. Once the structure is intact, workers finish the job by adding plumbing, electricity, and other final touches.

The process saves a lot of time.

"Typically, it would take nine to 15 months to manufacture a classroom out in the field," said Mike McKibbin, the head of operations for iMod. "We're doing that in twelve days."

Movable neighborhoods

Today, iMod Structures is focusing on future-proofing classrooms in California. But it's not hard to imagine how this kind of modular construction could transform not only the ways we build buildings but also organize cities. For example, if a company wants to set up offices in a new part of town, it could build an office park out of iMod Structures frames.

But what if the company needs to expand? It could attach more modules to its existing structure. If it needs to shut down? Instead of demolishing the office park, the structure could be modified and converted into, say, a hospital or apartment building. Alternatively, the modules could be removed from the site, and reused elsewhere, so the city could construct a park.

Under this kind of framework, cities could become far more flexible and dynamic, able to quickly adapt to changing needs. And with no need to demolish buildings, modular construction could prove far more sustainable than any method the industry uses today.

"We don't want our buildings to ever end up in a landfill. Ever," said Reed Walker, head of production and design at iMod Structures. "We want to take that system and use it again and again and again."

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    "I was intrigued," says Ron Fouchier, in his rich, Dutch-accented English, "in how little things could kill large animals and humans."

    It's late evening in Rotterdam as darkness slowly drapes our Skype conversation.

    This fascination led the silver-haired virologist to venture into controversial gain-of-function mutation research — work by scientists that adds abilities to pathogens, including experiments that focus on SARS and MERS, the coronavirus cousins of the COVID-19 agent.

    If we are to avoid another influenza pandemic, we will need to understand the kinds of flu viruses that could cause it. Gain-of-function mutation research can help us with that, says Fouchier, by telling us what kind of mutations might allow a virus to jump across species or evolve into more virulent strains. It could help us prepare and, in doing so, save lives.

    Many of his scientific peers, however, disagree; they say his experiments are not worth the risks they pose to society.

    A virus and a firestorm

    The Dutch virologist, based at Erasmus Medical Center in Rotterdam, caused a firestorm of controversy about a decade ago, when he and Yoshihiro Kawaoka at the University of Wisconsin-Madison announced that they had successfully mutated H5N1, a strain of bird flu, to pass through the air between ferrets, in two separate experiments. Ferrets are considered the best flu models because their respiratory systems react to the flu much like humans.

    The mutations that gave the virus its ability to be airborne transmissible are gain-of-function (GOF) mutations. GOF research is when scientists purposefully cause mutations that give viruses new abilities in an attempt to better understand the pathogen. In Fouchier's experiments, they wanted to see if it could be made airborne transmissible so that they could catch potentially dangerous strains early and develop new treatments and vaccines ahead of time.

    The problem is: their mutated H5N1 could also cause a pandemic if it ever left the lab. In Science magazine, Fouchier himself called it "probably one of the most dangerous viruses you can make."

    Just three special traits

    Recreated 1918 influenza virionsCredit: Cynthia Goldsmith / CDC / Dr. Terrence Tumpey / Public domain via Wikipedia

    For H5N1, Fouchier identified five mutations that could cause three special traits needed to trigger an avian flu to become airborne in mammals. Those traits are (1) the ability to attach to cells of the throat and nose, (2) the ability to survive the colder temperatures found in those places, and (3) the ability to survive in adverse environments.

    A minimum of three mutations may be all that's needed for a virus in the wild to make the leap through the air in mammals. If it does, it could spread. Fast.

    Fouchier calculates the odds of this happening to be fairly low, for any given virus. Each mutation has the potential to cripple the virus on its own. They need to be perfectly aligned for the flu to jump. But these mutations can — and do — happen.

    "In 2013, a new virus popped up in China," says Fouchier. "H7N9."

    H7N9 is another kind of avian flu, like H5N1. The CDC considers it the most likely flu strain to cause a pandemic. In the human outbreaks that occurred between 2013 and 2015, it killed a staggering 39% of known cases; if H7N9 were to have all five of the gain-of-function mutations Fouchier had identified in his work with H5N1, it could make COVID-19 look like a kitten in comparison.

    H7N9 had three of those mutations in 2013.

    Gain-of-function mutation: creating our fears to (possibly) prevent them

    Flu viruses are basically eight pieces of RNA wrapped up in a ball. To create the gain-of-function mutations, the research used a DNA template for each piece, called a plasmid. Making a single mutation in the plasmid is easy, Fouchier says, and it's commonly done in genetics labs.

    If you insert all eight plasmids into a mammalian cell, they hijack the cell's machinery to create flu virus RNA.

    "Now you can start to assemble a new virus particle in that cell," Fouchier says.

    One infected cell is enough to grow many new virus particles — from one to a thousand to a million; viruses are replication machines. And because they mutate so readily during their replication, the new viruses have to be checked to make sure it only has the mutations the lab caused.

    The virus then goes into the ferrets, passing through them to generate new viruses until, on the 10th generation, it infected ferrets through the air. By analyzing the virus's genes in each generation, they can figure out what exact five mutations lead to H5N1 bird flu being airborne between ferrets.

    And, potentially, people.

    "This work should never have been done"

    The potential for the modified H5N1 strain to cause a human pandemic if it ever slipped out of containment has sparked sharp criticism and no shortage of controversy. Rutgers molecular biologist Richard Ebright summed up the far end of the opposition when he told Science that the research "should never have been done."

    "When I first heard about the experiments that make highly pathogenic avian influenza transmissible," says Philip Dormitzer, vice president and chief scientific officer of viral vaccines at Pfizer, "I was interested in the science but concerned about the risks of both the viruses themselves and of the consequences of the reaction to the experiments."

    In 2014, in response to researchers' fears and some lab incidents, the federal government imposed a moratorium on all GOF research, freezing the work.

    Some scientists believe gain-of-function mutation experiments could be extremely valuable in understanding the potential risks we face from wild influenza strains, but only if they are done right. Dormitzer says that a careful and thoughtful examination of the issue could lead to processes that make gain-of-function mutation research with viruses safer.

    But in the meantime, the moratorium stifled some research into influenzas — and coronaviruses.

    The National Academy of Science whipped up some new guidelines, and in December of 2017, the call went out: GOF studies could apply to be funded again. A panel formed by Health and Human Services (HHS) would review applications and make the decision of which studies to fund.

    As of right now, only Kawaoka and Fouchier's studies have been approved, getting the green light last winter. They are resuming where they left off.

    Pandora's locks: how to contain gain-of-function flu

    Here's the thing: the work is indeed potentially dangerous. But there are layers upon layers of safety measures at both Fouchier's and Kawaoka's labs.

    "You really need to think about it like an onion," says Rebecca Moritz of the University of Wisconsin-Madison. Moritz is the select agent responsible for Kawaoka's lab. Her job is to ensure that all safety standards are met and that protocols are created and drilled; basically, she's there to prevent viruses from escaping. And this virus has some extra-special considerations.

    The specific H5N1 strain Kawaoka's lab uses is on a list called the Federal Select Agent Program. Pathogens on this list need to meet special safety considerations. The GOF experiments have even more stringent guidelines because the research is deemed "dual-use research of concern."

    There was debate over whether Fouchier and Kawaoka's work should even be published.

    "Dual-use research of concern is legitimate research that could potentially be used for nefarious purposes," Moritz says. At one time, there was debate over whether Fouchier and Kawaoka's work should even be published.

    While the insights they found would help scientists, they could also be used to create bioweapons. The papers had to pass through a review by the U.S. National Science Board for Biosecurity, but they were eventually published.

    Intentional biowarfare and terrorism aside, the gain-of-function mutation flu must be contained even from accidents. At Wisconsin, that begins with the building itself. The labs are specially designed to be able to contain pathogens (BSL-3 agricultural, for you Inside Baseball types).

    They are essentially an airtight cement bunker, negatively pressurized so that air will only flow into the lab in case of any breach — keeping the viruses pushed in. And all air in and out of the lap passes through multiple HEPA filters.

    Inside the lab, researchers wear special protective equipment, including respirators. Anyone coming or going into the lab must go through an intricate dance involving stripping and putting on various articles of clothing and passing through showers and decontamination.

    And the most dangerous parts of the experiment are performed inside primary containment. For example, a biocontainment cabinet, which acts like an extra high-security box, inside the already highly-secure lab (kind of like the radiation glove box Homer Simpson is working in during the opening credits).

    "Many people behind the institution are working to make sure this research can be done safely and securely." — REBECCA MORITZ

    The Federal Select Agent program can come and inspect you at any time with no warning, Moritz says. At the bare minimum, the whole thing gets shaken down every three years.

    There are numerous potential dangers — a vial of virus gets dropped; a needle prick; a ferret bite — but Moritz is confident that the safety measures and guidelines will prevent any catastrophe.

    "The institution and many people behind the institution are working to make sure this research can be done safely and securely," Moritz says.

    No human harm has come of the work yet, but the potential for it is real.

    "Nature will continue to do this"

    They were dead on the beaches.

    In the spring of 2014, another type of bird flu, H10N7, swept through the harbor seal population of northern Europe. Starting in Sweden, the virus moved south and west, across Denmark, Germany, and the Netherlands. It is estimated that 10% of the entire seal population was killed.

    The virus's evolution could be tracked through time and space, Fouchier says, as it progressed down the coast. Natural selection pushed through gain-of-function mutations in the seals, similarly to how H5N1 evolved to better jump between ferrets in his lab — his lab which, at the time, was shuttered.

    "We did our work in the lab," Fouchier says, with a high level of safety and security. "But the same thing was happening on the beach here in the Netherlands. And so you can tell me to stop doing this research, but nature will continue to do this day in, day out."

    Critics argue that the knowledge gained from the experiments is either non-existent or not worth the risk; Fouchier argues that GOF experiments are the only way to learn crucial information on what makes a flu virus a pandemic candidate.

    "If these three traits could be caused by hundreds of combinations of five mutations, then that increases the risk of these things happening in nature immensely," Fouchier says.

    "With something as crucial as flu, we need to investigate everything that we can," Fouchier says, hoping to find "a new Achilles' heel of the flu that we can use to stop the impact of it."

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