The Invention that Accidentally Made McMansions

This video is supported by Nebula. The more that I think about it, the more that I come to believe that this invention is responsible for the suburbs as we know it. This unassuming little piece of metal, it's called a gang nail plate or a truss plate. And its job is to affix pieces of wood together at their joints. What's really unique about it though, is that it can securely connect wood members positioned at almost any angle. With the aid of these plates, houses made of standard two by four studs can have open floor plans, cathedral ceilings, and complicated roof shapes, all constructed with ease. You might recognize all those three traits as the common features of modern suburban homes, especially the so-called McMansions. Yeah, these things make McMansions possible. But the impact that this plate has had, and the man who invented it on our world, does not end there by a long shot. And I wanna connect the dots. This is how this metal plate helped build the suburbs. To understand, let's head to Miami. Well, Miami before it looked like this. You know, when it looked a little more like this. This is what a typical house in Hialeah City, a suburb of Miami, might've looked like at the time. A small ranch style house, built sometime between the 1940s or the early 1950s. The problem was that roofs on houses like this were getting torn right off, or otherwise just getting damaged during the area's frequent hurricanes. These storms can punish structures with winds upwards of 100 miles per hour. And John Calvin Gerate, a civil engineer, was deeply concerned. He joined efforts to improve building practices by establishing the first building code for the area. While the codes covered a range of issues, Gerate himself studied the problem of roof failures during the high winds. Of course, he understood Bernoulli's principle, which explains how high speed winds flowing over a roof create a low pressure zone above it. Meanwhile, the high pressure inside the house pushes upward, essentially turning the roof assembly into an airplane wing that's prone to just lift right off. If you look closely at the construction, you can see exactly why this is a problem. The roof structure is made from a series of individual sloping rafters. The rafters need to be tied together with collar ties or ceiling joists to prevent them from spreading out and collapsing. But each time sloping pieces connect, one piece is often pushed to one side, extended, and overlaps so that it can be nailed securely to the other members. Where you can't do that, like at the sill plate, the wood is connected with a technique called toe nailing. That's when nails are driven in at a sharp angle through the corners of the wood. This isn't a very strong way to do it, and it's awkward for carpenters to try to nail into the wood at this sharp angle. It's in places like this that the roof was failing. Not only that, but all of these angled cuts, that's exactly where the carpenter skill is being put to the test. Any small error in this area is magnified into weakened construction, and it's where you waste a ton of wood. Every angled cut leaves scrap that just gets thrown away. Weak, hard to make, and expensive. That's hardly what you want in hurricane-prone Florida, or anywhere for that matter. That's a problem. So Gerait went home and sketched something that looked a lot like this, the first prototype of the gang nail plate connector. It's made by stamping sheets of galvanized steel, cutting and bending tiny strips into sharp nail-like spikes. It can be pressed onto boards, and instead of toe nailing with two or three nails, you get dozens of spikes gripping the wood at each joint. If we use this technique for the roof on our Hialeah house, a plate would go on each side of every joint. We go from overlapping the boards or toe nailing to strong inline connections. After securing the patent, Gerait went into production. It was an immediate success. Everyone saw the value in it, and he quickly noticed how it changed the way that people were making roofs in general. Instead of using individual rafters with ties, the plate allowed contractors to efficiently use trusses. Trusses have many more connections than simple rafters do, which made them impractical for residential construction before. They're just too labor-intensive and expensive to build on site, but the benefit is that they can be made with smaller pieces of wood. By using the power of geometry, you can arrange the wood pieces to span further with less material overall. Instead of large rafters that are limited by a size of trees, we have light, efficient trusses crisscrossing above our heads. These can span significant distances, without the need for any interior support walls. What's even better is that these trusses can be made off-site, in a factory, and then from there, they're shipped complete and lifted into place with a small crane or a boom. By targeting one of the most complicated and expensive parts of the house, this single invention can save up to 25% of the lumber when compared to previous construction techniques for roofs. For a 2,000 square foot house, that could be around 1,000 board feet of lumber saved. Building trusses in a factory also reduces wood waste by up to 15% just by itself, because cuts can be pre-planned more efficiently. Over about 100 houses, that's enough wood to build several more houses. It reduces roof construction time by half, meaning every house can be finished about two or three weeks earlier than it would have been otherwise. And all of these benefits can be had for about 15 to 25% less costs than other roof methods. I personally cannot think of a single invention that is so simple that has created such a profound effect on the way that we build. Gerate has been compared to Henry Ford for how he ushered in a new era for housing by shifting a significant portion of its construction to an assembly line. Not only did Gerate go into business making these plates, he created an entire new operation strategy that delivers finished trusses to the job site. Gerate's final hurdle for wide adoption though was to get these new plates and technology approved for use in the building code that he used to work on. So since Gerate was on that committee, coupled with the fact that the nail plate was simply performing better, the case was pretty simple. By the early 1960s, the plates were approved for use within building codes across the US. They added a new line in the building code in the section on wood construction for trusses. By the 1970s, pre-manufactured trusses became the norm in suburban residential construction. And this impacted the design of how houses looked and functioned. You can probably spot the difference between a house built in the 1940s and the 1970s. You might not attribute them to the truss construction though. So let's look a little bit more closely to see how those add up. First, trusses make it more difficult to occupy the space that's underneath of a sloped roof. So attics become less common once trusses are adopted. This was often offset with storage in the basement or in large garages like you see in this one, depending on the regional building practices. Another feature is that you can have a deeper floor plan without the need for multiple roof slopes because the truss can span further with smaller pieces of wood. The higher strength to weight ratio also means that it can span the entire width of the house without the need for any internal support walls. All the weight of the roof is carried down through the outer walls. Since these exterior walls are carrying the majority of the load, they might be built with larger wood members, maybe two by sixes instead of the standard two by fours. And that just gives more space for the insulation to occupy. Meanwhile, there are no interior walls that bear the weight of the roof. So let's say you want larger spaces on the first floor with a series of smaller bedrooms on the top. That's more difficult to do with the older system where the internal walls probably carry the weight of the room. The walls of the bedrooms may need to align and carry down that weight down to the first floor. But when these don't take any of that weight, the floors work completely independently. And the first floor can be completely open while the second has lots of walls in it. While you might not know that all these features are made possible using trusses, you can probably just feel the difference in the openness or the lack of attics and things like that. But of course, these are all just a small price to pay for all of the benefits. Then during the 1980s, things started to take a bit of a turn. Home builders started to become the main characters and they recognized that larger homes were more profitable than the smaller ones. They started to prioritize size and complexity over things like quality and sustainability. And at this time, homes started to shift to become more of an investment vehicle than just a place to live. At the same time, the oil crisis eased and financial markets boomed in the wake of new technologies, there was more money, cheaper gas, and an incentive to build big, often by the people who weren't even planning to live inside of these homes. I think it's no coincidence that the company that Gerait founded, it was among the first to use computer-aided design for building components. They bought a $1 million room-sized computer to calculate the truss forces and designs. And it was a good thing too, because things, they were about to get crazy. Enter the McMansion. McMansions. A McMansion. McMansions. What people here are calling a McMansion. These things are built even further away from cities and they took all of those things that we discussed as being features of the 1970s homes that we attributed to the truss and exaggerated them. Huge, complicated, often uninhabitable roofs, along with sprawling open floor plans. The multitude of roof peaks everywhere became almost a caricature of a house, a supersized symbol of excess. When I view these in this lens, I think that these houses almost look like they're specifically designed to showcase what trusses and gangnail plates made possible. Just look at how many trusses are up there. That's probably what these two dudes are talking about. Trusses also make cathedral ceilings affordable through something called a scissor truss. Imagine the bottom part of the truss angling upward like the open pair of scissors. Even those gigantic foyers that we associate with these kinds of buildings became possible because of the truss plates. So, here's the big irony. The invention that's meant to make homes stronger and more efficient also played a huge role in creating less sustainable living patterns. Instead of pocketing the savings that the truss plates offer, our houses ballooned to fill the gap, using even more energy and materials in the end. It shifted our values from the handcrafted to the mass-produced, from the unique to the uniform. It stretched our cities outward, consuming landscapes and altering our ecosystems. It changed how we interact with all sorts of things, just like our homes, our neighbors, and our environment, and not always for the better. It is crazy to me that an invention for our roofs could lead to such a wide array of unintended consequences. If we just look at the sociological studies of things like open plans, we can find all kinds of ways that these changed our behaviors, none of which were part of Gerait's original plan. Research like the UCLA study, Life at Homes of the 21st Century, shows that the open floor plans do facilitate interaction between family members, but that comes at the cost of added stress, as everyone is exposed to noise and activity all the time. While open spaces make it easier to be together, they also make it more difficult for individuals to withdraw for solitude or to feel like they have any control over their individual environments. Shared spaces also just tend to accumulate clutter, contributing to the feelings of disorganization and stress overall. And if psychological trauma isn't enough, by the 2000s, rapid home construction accelerated by the efficiencies that were made possible by the trust plate contributed to overproduction in the housing market. The trend towards larger homes increased household debt, while the construction surge contributed to this misguided perception that homes were just gonna increase in values forever. Berkshire Hathaway purchased Gerait's company in 2001, and seven years later, the housing market collapsed, and Berkshire Hathaway became the company that bailed everyone out and pocketed billions. So look, I am not blaming the last 60 years of suburban sprawl, aesthetic erosion, and the biggest economic meltdown since the Great Depression solely on Calvin Gerait and his trust plate. But sometimes it's hard to untangle cause and effect. Did we start wanting open floor plans and elaborate roofs just because they became possible, or was the trust fulfilling some innate desires that we had for our homes that just wouldn't have been feasible before? Was the commodification of housing inevitable, or was it accelerated by new production methods? Every innovation carries with it a set of consequences, some intended and some that show up unexpectedly. The gangnail plate didn't just build suburbia, it shaped a significant part of our modern world, for better or for worse. Building a certain way just because we can isn't the same as building the way we should. I find these unexpected moments like trust joints fascinating for how their outsized impact shapes our world around us. It seems like you might be right there with me too, and that's why I think that you'll love what's waiting for you on Nebula. Nebula is a streaming service built by creators for curious minds like ours. 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