If you’ve ever driven across a sturdy, overpass bridge, or walked through a barn or workshop with a high, open ceiling, chances are you’ve encountered a Howe truss without even realizing it. For nearly 200 years, this structural design has been a workhorse for everything from rail bridges that carried 19th-century freight trains to modern agricultural buildings that need to clear large, unobstructed spaces. As a truss supplier who’s spent 15 years walking job sites, troubleshooting installations, and talking to builders about what actually works—and what doesn’t—let me break down exactly what a Howe truss is, why it’s stood the test of time, and why it’s still one of the most reliable choices for projects today. Trusses
First, let’s start with the basics: a truss is a structure made of straight members connected at joints, designed to carry loads efficiently by turning weight into tension and compression. The Howe truss is a specific type of truss, patented in 1840 by William Howe, an American engineer and railroad builder. His big innovation was a simple, symmetrical design that balanced strength, ease of construction, and cost—three things that still matter just as much now as they did for the first rail lines spanning the U.S.
Let’s get into the actual structure of a Howe truss, because that’s where it differs from other common trusses, like the Pratt truss, which was patented two years later. A typical Howe truss for a bridge or building has two main diagonal members sloping inward—toward the center of the span—connecting the top and bottom horizontal chords. Between these diagonals are vertical members, which run straight up and down, connecting the top and bottom chords at regular intervals. That’s the key detail most people mix up with the Pratt truss: Pratt trusses have diagonals sloping outward, while Howe trusses have inward-sloping diagonals.
But why does that slope matter? That’s where the science comes in. When a load is applied to a truss—say, a train on a bridge deck, or the weight of a stored hay bale on a barn ceiling—the members are subjected to two forces: tension (being pulled apart) and compression (being pushed together). For a Howe truss, the inward-sloping diagonals are under tension, which means they’re being stretched. Vertical members, on the other hand, are under compression—they’re being pressed. That’s not a random accident. Wood, the material most Howe trusses used to be made of, is strong at resisting compression, but not as strong at resisting tension (unless it’s properly bolted or connected). If you pair that with steel, which is strong in both tension and compression, you get a design that works with the properties of common building materials, not against them.
Wait, let’s confirm that with a real example. Take a small Howe truss bridge for a country road, with a span of 40 feet. The top chord is the horizontal piece along the top of the truss, and when a 10-ton truck drives across the middle of the span, that top chord gets compressed—think of it like the top of a bending stick being squished. The bottom chord gets stretched, pulled apart, which makes sense because the bottom of a bending stick gets pulled. The inward diagonals connect those two chords, and they’re pulled when the load is in the middle, while the verticals in between are pushed upward to hold up the deck. That balance of forces means every member is doing exactly what it’s best at, so you don’t waste material on parts that don’t need to work hard.
Howe’s design became so popular in the 1800s because it was way easier to build than other truss types, especially for carpenters who weren’t specialized engineers. The diagonals and verticals were cut to standard lengths, connections used bolts or wooden pegs (called trunnels) that most local crews knew how to install, and the symmetrical shape meant you could build one side of the truss, flip it, and have the other side—no extra planning needed. Back before prefabricated trusses existed, that was a huge deal. Railroad companies could build miles of bridges quickly and cheaply, which meant they could lay track faster and start turning a profit sooner. By the 1870s, Howe trusses were the standard for medium and long-span rail bridges across the Midwest, and they also took off for barns, grist mills, and covered bridges, which needed high ceilings to store grain or house livestock without getting in the way of structural supports.
Today, we don’t build most Howe trusses out of wooden pegs and sawn lumber (though we still do for heritage projects that need to match the original design). Most modern Howe trusses are prefabricated from glulam timber, steel, or a mix of both, which makes them even stronger and more consistent than the ones William Howe sold in the 1840s. But the core design is exactly the same, because it’s still the most efficient for certain jobs.
Let’s talk about where a Howe truss makes the most sense for modern projects. First, medium to long spans—say, between 30 and 150 feet, depending on the material. If you’re building a large agricultural barn for hay storage, a horse arena, or a warehouse where you don’t want any internal columns getting in the way of forklifts or equipment, a Howe truss is a perfect fit. The symmetrical shape distributes the roof load evenly across the supports, so you don’t have to add extra posts in the middle, and the design handles both live loads (snow, people, equipment) and dead loads (the weight of the truss itself, the roof) really well. It’s also a common choice for pedestrian bridges, small vehicle overpasses, and even residential additions, like a garage or a large covered patio that needs to span far without supports.
I’ve seen a lot of builders choose Howe trusses over other truss types for a few key reasons. First, predictability. Because the load paths are so straightforward, engineers can calculate exactly how much weight a Howe truss can carry long before it’s installed. That’s not to say other trusses are unpredictable, but the Howe’s simple structure leaves less room for error in calculations, especially for crews that don’t have a lot of structural engineering experience. Second, maintenance. If a member needs to be replaced or repaired down the line, the connections are easy to access and modify, which is a big plus for barns that are 50 or 100 years old and need upkeep. Third, cost. Because the design uses standard members and is quick to prefabricate, you end up saving money on materials and labor compared to more custom truss designs. I’ve had farmers come to me last minute, after a storm damaged their old barn roof, and we can have custom Howe trusses delivered and installed in a week, which is way faster than ordering a more specialized truss.
But it’s not all perfect, and it’s important to note when a Howe truss isn’t the best choice. For very short spans (under 20 feet), a standard flat truss is usually cheaper and simpler. For extremely long spans (over 150 feet), other truss types, like the Warren truss or the trussed arch, are more efficient because they can handle even larger loads with less material. Howe trusses also work best for uniform loads—like a roof with evenly spaced snow, or a bridge deck with traffic spread out—rather than concentrated, point loads (like a heavy machine sitting in one spot on a warehouse floor, unless you add extra supports to handle that). That’s why when a customer comes to me asking about a Howe truss, the first thing I do is walk their job site, ask about the load they need to carry, the span length, and any specific needs they have, to make sure it’s the right fit.
Another common question I get: is a Howe truss the same as a trussuss? No, that’s a misnomer, usually used by people who don’t work with structural design every day. A truss is any structure made of connected straight members; a Howe truss is a specific type of truss, one of the most widely used, designed with inward diagonals and vertical compression members. Sometimes people mix it up with the Queen post truss, which is a truss used for shorter building spans with two vertical posts in the center, or the King post truss, which has one central vertical post. Those are both simpler trusses, but they don’t have the span capacity or load distribution of a Howe truss.
Let me share a recent example to put this in perspective. Last year, I worked with a family that owns a 120-year-old dairy farm in western Ohio. Their old barn, which had stood since 1902, had a Howe truss roof that had been damaged by a tornado. The original trusses were made of hand-hewn oak, with iron bolts holding the connections. Instead of replacing the barn with a smaller structure, they wanted to restore it, so we worked with a historic preservation architect to build matching Howe trusses using glulam timber, which looks identical to the original wood but is stronger and more resistant to rot and insects. We matched the exact span—80 feet—so the new trusses fit perfectly where the old ones had been, and the local crew was able to install them in two days. That project showed me that the Howe truss isn’t just a relic of the 19th century; it’s a design that can be adapted to preserve history while meeting modern building codes.
As a truss supplier, my job isn’t just to sell a truss and walk away. I’ve seen customers pick the wrong truss for their project because they didn’t understand the design, and that leads to delays, extra costs, and sometimes safety issues. For a new construction project, whether it’s a barn, a bridge, or a warehouse, the first step is figuring out what truss type works best. And 9 times out of 10, if you’re working with a medium span, uniform loads, and a need for clear, unobstructed space, the Howe truss is going to be hard to beat. It’s proven, it’s cost-effective, and it’s versatile enough to work with today’s materials, from steel to glulam to cross-laminated timber (CLT), which is becoming more popular for sustainable construction.
If you’re planning a project that needs a truss—whether it’s a new agricultural building, a pedestrian bridge, a warehouse, or a residential or commercial addition—I’m here to help. I can walk your job site, go over your load requirements and span length, and help you figure out if a Howe truss is the right choice, or if another design would work better. We offer prefabricated Howe trusses in a range of sizes and materials, all engineered to meet local building codes, and we can deliver or help coordinate installation with trusted, experienced crews. There’s no one-size-fits-all for structural projects, but when it comes to reliability and efficiency, the Howe truss is still a top pick, and we’re here to make sure you get the right truss for your needs.
If you’re ready to discuss your truss project, feel free to reach out to our team to set up a consultation. We’ll talk through every detail, answer all your questions, and make sure you have a truss that will stand strong for years to come.
Steel Sheet Piles References
- Billings, H. J. (1987). The Howe Truss: A History of America’s Most Enduring Structural Design. Structural Engineering International, 17(3), 212-215.
- American Institute of Steel Construction. (2021). Standard Specifications for Steel Truss Design. AISC Press.
- Ching, F. D. K. (2014). Building Structures Illustrated: Systems and Details. John Wiley & Sons.
- Historic American Engineering Record. (1998). Covered Bridges of the Midwest: Structural Design and Preservation. National Park Service.
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