The Hidden Forces That Build America: Arching Action and the Tools We Trust Words: Shayne SandersMost people at World of Concrete can identify a CMU block from 50 feet away. Some can even smell Type S mortar curing from across the hall. But mention the phrase “arching action,” and you will see a surprising number of boots shift and eyes drift toward the nearest coffee stand.That is the interesting thing about masonry. The part everyone sees is only the surface. The real work often happens inside the wall, quietly and reliably, where chemistry and physics team up to keep the integrity of the wall and openings exactly where builders intended them to stay. Every year at WOC, we are reminded that nothing on the jobsite works harder than the unseen forces that hold our structures together. Well, except maybe the crew trying to roll a pallet jack across the carpet in South Hall.Arching action is not an abstract theory. It is the reason openings perform. It is the silent muscle behind lintels, jambs, and walls that stand true. And when the right conditions exist, it becomes one of the strongest forces available to a mason.Arching ActionThe Strength Most People Forget ExistsArching action takes place when masonry redirects the load around an opening and carries it into the structure, the way it was designed to. When the geometry is correct, the wall mass is sufficient, the bearing is right, and the temporary support is reliable, the wall begins to support itself.Masonry is a naturally self-stabilizing system. It will take over the job if you give it the chance. The challenge is making sure nothing interferes with that process while the mortar is curing.When arching action is restricted or allowed to develop unevenly, problems show up. Cracks form where none should exist. Lintels take on unintended loads. Openings sag. Head joints reveal that something was not right on day one. And callbacks arrive that could have been avoided with better planning.The Consequences of Improper ShoringAsk any mason, GC, or engineer, and you will hear a story about temporary shoring. These stories usually involve a field-built wood buck that leaned, twisted, or sagged enough to make everyone nervous. Even a small imperfection influences how the wall cures and how it will behave later.Mis-shoring tends to produce the same results again and again:Load paths never redirect because the buck absorbed the weightHead joints crack when the support bows under pressureOut-of-plane movement develops if the support is pulled too earlyLintels carry more than they should because arching is never engagedHere is the irony. WOC is filled with contractors who would never slide a random scrap of lumber under a heavy machine. Yet temporary masonry support is often built from whatever wood happened to arrive on the truck that morning. Some bucks are fine. Many are not. Almost all are inconsistent. And none of them guarantee the straight, square, rigid support that proper arching action requires.The Rise of Modern Temporary SupportAcross the country, contractors are leaving homemade wood bucks behind in favor of engineered steel systems or pre-cast systems. The shift is driven by the rising demand for increased productivity, consistency, predictability, and cleaner openings. Crews are tired of spending valuable labor time building temporary structures that will be thrown away. They are tired of inconsistent results and callbacks tied to preventable movement.Engineered support is not about being fancy. It is about being consistent. Masonry behaves the way it is supposed to when its temporary support is straight, square, and level. Clean openings do not happen by accident. They happen when someone on the jobsite respects gravity enough to plan ahead and ensure they get the best solutions at the right time.At WOC each year, contractors are clearly searching for predictable systems that reduce the variables on their projects and save time and money. GCs want fewer surprises, and Engineers want structures that respond to load the way they intended. And crews want to build without fighting their support.A Conversation with Scot Kelly of Quick HeadersTo explore how temporary support shapes real jobsite outcomes, we spoke with Scot Kelly, owner of Quick Headers and a driving force behind the effort to bring smarter, safer, and more cost-effective shoring solutions to masonry contractors nationwide. Scot has watched thousands of openings go up and has seen nearly every method of shoring in practice.Q: In your experience watching thousands of openings go up, what is the most misunderstood part of temporary supportScot:“The biggest misconception is thinking you can simply wing it with whatever might be lying around the job site. The consequences of insufficient or poorly installed shoring can be far more costly than the expense of building the project in the first place. Quick Headers are so much more efficient and cost-effective that it will always be the best option without even accounting for a catastrophic failure on a wall.Temporary support shapes how the wall cures and how it will perform for the rest of its life. If the buck is twisting or sagging or taking load the wrong way, the wall cures around that mistake and carries it forever.Arching action is trying to do its job, but it needs the right environment. When your support is rigid, square, and consistent, the load moves exactly where it should. When it is not, the wall fights itself. I have seen a lot of long-term problems that can be traced straight back to temporary support that did not do its job on day one.”Q: What advice would you give a crew switching from wood to engineered shoring for the first timeScot:“My advice is simple. Do not overthink it. You are not changing the way you lay blocks. You are just giving the wall a better starting point.Most crews are surprised by how much cleaner their openings become. Inspectors notice it right away. GCs notice it because it reduces callbacks. The masons notice it because their work is easier when the support under them is not moving with the weather.Once a crew sees how predictable it is, they do not want to go back to building wood bucks. It is safer. It is faster. And it is usually cheaper once you account for labor and waste. Trust the support and let the masonry do its job. When your support is predictable, your results are predictable.”Scot’s perspective captures what the industry has been moving toward for years. Clean, consistent, engineered temporary support is no longer a luxury. It is a necessary part of building masonry that performs the way it was designed.Pulling It All TogetherThe Modern Jobsite Depends on PredictabilityThe industry is far past the point where good enough is acceptable. Masonry is a precision system, and arching action only works when temporary support is straight, rigid, properly placed, and designed for the load. In a world where every minute is billable and every mistake is documented, clean openings carry real value.They show that the wall was given the structure it needed to cure correctly. They reflect craftsmanship. And they give everyone on the job one less thing to worry about.At World of Concrete, thousands of professionals walk the floor looking for systems that make their work safer, faster, and more consistent. The best tools do not just hold up masonry. They support the people who build it.World of Concrete brings out the best of the industry. New tools, new ideas, and thousands of people who know that gravity does not take a day off. The hidden forces inside a masonry wall will always be there, working quietly and faithfully.Our job is simple. Give those forces the support they deserve.About: Technical Talks
