Introduction
Steel props—adjustable temporary supports used to hold up ceilings, support concrete slabs, and stabilize excavations—are among the most essential tools in modern construction. But how did we get from rough-hewn timber braces to today’s precision-engineered steel shoring systems? This article traces the complete history of steel props, from ancient timber origins through revolutionary innovations in adjustable steel technology, and explores where the industry is heading next.
Whether you’re a contractor, engineer, or construction professional, understanding the evolution of temporary support systems helps you appreciate the safety and efficiency benefits of modern steel props—and make better decisions for your projects.
Ancient Origins: The Timber Era
The Birth of Temporary Support
Long before steel became the material of choice, construction workers relied on timber for temporary structural support. The earliest shoring techniques can be traced back hundreds—if not thousands—of years. The word “shoring” itself derives from “shore,” an old term for a timber or metal prop [11†L4-L5].
In the early days of construction, builders manually cut and braced wooden beams to support structures during work. While effective, these systems were labor-intensive, inconsistent in quality, and difficult to reuse [19†L17-L20].
19th Century: The Timber Peak
The first documented use of ground shoring dates back to the 1860s in London, during the construction of the city’s sewer networks. Timber support was common practice, but the depth and size of excavations were fundamentally limited by the size of timber available—generally restricting spans to about 10 meters [6†L10-L14].
These early excavations were typically undertaken by miners and navvies who came from coal mining and canal construction, bringing their ground support techniques to the building industry [6†L15-L17].
The construction of the London Underground in the late 19th century pushed these techniques further. Early routes were built using “cut and cover” methods along street alignments, employing traditional timber support techniques. Later lines went deeper, using tunneling shields, but traditional excavation support remained the standard for accessing tunnel depths [6†L18-L22].
What engineers achieved with these now-primitive techniques is remarkable—many sewers and train tunnels excavated using these methods remain in service today [6†L24-L26].
Early 20th Century: The Limits of Timber
Into the 1920s and 1930s, timber remained dominant. In the mining industry, which was a major driver of shoring technology, wooden props were widely used but had serious shortcomings. At a colliery in North Wales in the early 1930s, every single wooden prop broke, requiring additional chocks to be set to keep the roof from collapsing [10†L19-L25].
Timber props presented another critical limitation: once a wooden prop failed under excessive load, it became completely useless. Steel props, by contrast, would bend when overloaded but continue to develop useful resistance [1†L34-L36].
By 1931, steel props had been introduced in British mines—6-inch by 5-inch section props that “revolutionised the conditions.” Falls of roof at the working face, which previously threatened both safety and productivity, no longer occurred. Miners began clamoring for steel props despite their increased weight, recognizing the dramatic improvement in safety and reliability [10†L20-L33].
The Great Leap Forward: The 1930s Adjustable Steel Prop
W.A. de Vigier’s Revolutionary Invention
The most significant breakthrough in temporary support technology came in 1935, when Swiss inventor W.A. de Vigier designed the first adjustable steel prop—a development that “revolutionized many aspects of the construction industry including to support slab formwork, wall formwork, trench sheeting and falsework” [20†L29-L32].
This single steel prop could have its height adjusted using a screw jack mechanism—simple in structure but transformative in application. The adjustable steel prop’s ability to be easily dismantled and reassembled, its convenient transportability, and its strong versatility led to rapid adoption worldwide [21†L20-L24].
Two Design Approaches Emerge
As the technology spread, two distinct design philosophies emerged:
Screw thread exposed props – Simpler and less expensive, but vulnerable to damage and contamination
Screw thread closed props – Enclosing the threaded mechanism to prevent dirt, mortar, and debris from freezing or jamming the adjustment system, while also protecting threads from damage during use and handling [21†L24-L29]
The enclosed design gained particular popularity across European countries, where construction conditions often demanded greater protection for moving parts [21†L29-L30].
The Birth of “Acrow Props”
In 1936, just one year after de Vigier’s invention, a company called Acrow Limited was founded in the United Kingdom. Acrow would go on to become synonymous with adjustable steel props to such an extent that the brand name became a generic term. Today, “Acrow props” is used worldwide to refer to any type of adjustable steel prop or telescopic prop, regardless of manufacturer—a testament to the company’s foundational impact on the industry [15†L3-L8].
These adjustable steel props—also known as Maxi props when they were introduced to the market—offered unprecedented strength, reliability, and ease of use, setting new standards for safety and efficiency on construction sites [5†L12-L15].
Post-War Expansion and the Steel Revolution (1940s–1970s)
World War II’s Catalytic Effect
While adjustable steel props had been invented before the war, World War II created conditions that dramatically accelerated their adoption. The need to undertake repairs to war-damaged structures drove demand for better temporary support solutions [6†L36-L37].
In the United Kingdom, the economic recovery of the construction market in the mid-1950s meant major developments were undertaken on bomb sites—the first structures to have deep foundations. These projects demanded shoring capabilities that timber alone could not provide [6†L39-L43].
Structural Steel Takes Over
As excavations became deeper and support spans grew wider, structural steel began replacing timber frames. Basements excavated with timber and steel sheet pile support reached considerable depths [6†L37-L39].
Between 1955 and 1970, basement walls were commonly built using diaphragm wall techniques, and tripod rig piling introduced piles up to 600mm in diameter—further increasing the demand for robust steel shoring systems [6†L47-L51].
The American Steel Sheet Piling Revolution
In the United States, another major innovation was taking shape. Steel sheet piling—thin steel plates driven into the ground to form a continuous retaining wall—was patented in the 1890s and entered commercial production in the early 1900s. Before its introduction, contractors had no effective means of installing shoring systems in challenging soil conditions [8†L10-L14].
After World War II, small backhoes and large excavators were developed that were mobile enough and strong enough to move and set shoring equipment. This led to the proliferation of hydraulic aluminum shores and steel shoring shields, dramatically expanding what was possible in excavation support [7†L55-L56].
Shoring Systems Diversify
This period saw the emergence of most major shoring system categories used today:
Aluminum hydraulic shores – Allowed rapid installation and removal
Steel shoring shields – Provided worker protection in trenches
Steel trench plates – Covered excavations to allow surface traffic
Slide rail systems – Introduced in Europe, they took decades to gain traction in the United States [7†L13-L17][2†L26-L28]
These innovations transformed shoring from a skilled craft into an engineered science.
The Safety Era: Regulation and Standardization (1980s–2000s)
OSHA Subpart P: A Regulatory Turning Point
The adoption of the OSHA Subpart P—Excavation Standard in 1990 had a major impact on the shoring industry. Unlike earlier prescriptive standards that specified exactly which techniques to use, Subpart P was “results-based,” leaving the industry to determine how to more safely and effectively complete work while complying with the standard [7†L18-L22].
This regulatory shift created powerful incentives for innovation. Contractors who failed to comply faced increased bodily injury, property damage, costly fines, and lawsuits—risks substantial enough to put companies out of business [7†L24-L28].
Safety Drives Standardization
As safety devices were developed in response to accidents and became available on the market, they quickly became industry standards. Ramps, bridges, ladder access platforms, and handrails for accessing shoring shields evolved from optional add-ons to mandatory requirements. Carpenters who once built these devices on-site by hand gave way to manufactured steel and aluminum access devices available for rental or sale [7†L33-L47].
This safety-driven evolution had ripple effects across the industry. Even when regulations didn’t explicitly require certain safety equipment, using it became a matter of legal prudence—because a lawyer could argue in court that a contractor who failed to use commercially available safety equipment showed “improper concern for the safety of their employees” [7†L44-L47].
British Standards Lead the Way
In the United Kingdom, falsework design and use were codified under British Standard BS 5975. First introduced by the British Standards Institute in March 1982 and revised in 1996, the standard was later updated to align with new European codes: EN 12811-1:2003 (Temporary works equipment—Scaffolds) and EN 12812:2004 (Falsework—Performance requirements and general design) [20†L42-L50].
These standards created consistent design, testing, and performance expectations for steel props, reducing variability and increasing safety across the industry.
Modern Steel Props: The Multi Prop Revolution (2000s–Present)
From Maxi Props to Multi Props
The mid-20th century introduced adjustable steel props—called Maxi props in many markets—which remained the standard for decades. But the 21st century has seen the emergence of “multi props,” representing the next generation of temporary support systems [19†L25-L26].
Multi props are designed for high-performance applications and offer significant advantages:
Superior load capacity for demanding structural work
Precision adjustability for accurate height control
Modular compatibility with scaffolding, formwork, and falsework systems
Enhanced safety features, including locking mechanisms and reinforced base plates
While Maxi props remain a reliable choice for smaller load-bearing tasks and general support, multi props are becoming the preferred solution for heavier loads and complex formwork systems [19†L27-L35].
Aluminum and Advanced Materials
Material technology has driven significant improvements in prop performance. High-strength aluminum alloys and powder-coated finishes have extended service life, reduced maintenance requirements, and made props significantly lighter and easier to handle [19†L40-L41].
Some manufacturers now achieve service lives exceeding 10–15 years under proper use and maintenance—making steel props increasingly cost-effective over their full lifecycle [5†L17-L21].
Modular System Integration
Modern multi props are engineered to work seamlessly with modular systems, allowing for faster setup and more adaptable configurations on site. This modular integration means a single set of components can be reconfigured for multiple applications, reducing the number of distinct parts a contractor needs to inventory [19†L42-L43].
Tubular shoring systems have reached impressive capabilities—available with maximum load capacities from 1,400kN to as high as 15,000kN [4†L17-L21].
Global Manufacturing and Market Evolution
China’s Transformation
The story of steel props cannot be told without acknowledging China’s dramatic transformation. Before 1949 and into the early 1950s, scaffolding and shoring in China were built almost exclusively from bamboo or wooden structures—following a traditional “South Bamboo, North Wood” principle that persisted for centuries. In the 1960s, steel pipe scaffolding with couplers was promoted, marking the beginning of China’s transition to modern shoring systems [5†L27-L29].
Today, China is the world’s largest manufacturer and exporter of steel props, scaffolding, and formwork systems, producing everything from basic adjustable props to highly engineered ringlock systems that meet international standards.
Australia’s Quadshore Innovation
A recent standout example of ongoing innovation comes from Australia. The Quadshore lightweight propping solution—a joint project by Coates Hire, Monash University, and Knox Engineering—was voted “Innovation of the Year” at the World Steel Association’s constructsteel Awards 2023 [9†L2-L8].
Quadshore uses lightweight, high-strength steel structural elements and boltless connections. Where conventional propping systems made of low-grade steel are heavy and hard to use, Quadshore’s revolutionary design makes construction sites more efficient and safer. This project demonstrates that even in a mature industry, genuine innovation remains possible [9†L9-L13].
Acrow’s Global Reach
Acrow, whose name became synonymous with adjustable steel props, has evolved into a global enterprise. The original Acrow Limited was founded in the UK in the 1930s. Today, Acrow entities operate worldwide—including Acrow Bridge in Parsippany, New Jersey (founded in the US in 1951), and Acrow Limited in Australia (founded 1936, now listed on the Australian Securities Exchange as ACF). Acrow’s Superprop shoring systems continue to support major infrastructure projects, including parts of Interstate 10 in New Mexico [3†L17-L26].
Current Market Size and Growth
The global shoring equipment market has grown substantially alongside construction activity worldwide. The market for iron or steel equipment for scaffolding, shuttering, propping, and pit-propping represents a significant international trade sector [5†L30-L37].
Recent data shows that steel props now make up approximately 40 percent of shoring rental volume for many contractors—up from 28 percent just two years ago. Many rental yards now offer “pour packages” that bundle galvanized steel prop units with base plates and head jacks, matched to typical slab thicknesses for commercial and industrial work [5†L4-L9].
The concrete shoring system sector has evolved into a critical backbone for modern construction projects, responding to escalating demands for safety, efficiency, and sustainability [17†L6-L8].
Future Trends: Where Is Steel Prop Technology Headed?
Lightweight Materials and Composites
Industry experts predict significant changes in shoring materials over the coming decades. RMD Kwikform’s commercial director John Breen anticipates that steel usage will diminish in favor of high-grade alloys with better strength-to-weight ratios, along with robust carbon fiber materials. “Rather than having big steel tubes, we will have large spun carbon fiber props—which are much more durable” [13†L20-L25].
Other experts see a shift toward polymers and glass reinforced plastic (GRP) for shallower excavations, where lighter components offer substantial handling advantages. However, quality control remains a challenge—steel is a repeatable, closely controlled product, while composites can vary in thickness and material composition [13†L25-L38].
Digital Integration and Smart Shoring
Digitalization is reshaping how shoring systems are designed, monitored, and maintained:
Building Information Modeling (BIM) allows for 3D simulations of excavation and shoring, identifying risks before digging begins [18†L34-L35]
Real-time monitoring sensors track soil movement, wall pressures, and vibrations, enabling proactive responses to potential failures [18†L35-L37]
IoT-enabled sensors embedded within shoring assemblies enable stakeholders to monitor performance metrics dynamically and optimize support configurations remotely [17†L34-L36]
Predictive maintenance protocols driven by real-time data on stress, displacement, and soil movement are reducing the risk of structural failure and cost overruns [17†L16-L18]
Doka’s Doka 360 platform represents the next leap forward—an integrated connected platform that brings together digital tools including Concremote, DokaXact, and future smart services into one ecosystem designed to optimize planning, execution, and monitoring of shoring systems [16†L20-L26].
Sustainability and Circular Economy
Sustainability imperatives are driving material science breakthroughs in shoring. Aluminum alloys engineered for low weight and high corrosion resistance, along with engineered timber alternatives selected for renewable sourcing, illustrate the sector’s commitment to minimizing carbon footprints [17†L22-L29].
High-performance aluminum alloys and engineered timber alternatives are gaining traction alongside traditional steel components, signaling an industry-wide commitment to circularity and reduced embodied carbon. Regulatory frameworks around waste management and emissions are further stimulating innovation, encouraging the adoption of recyclable components and eco-friendly coatings [17†L45-L51].
Automation and Robotics
Semi-automated systems are already emerging. Doka’s Shear Wall Climber with FormDrive introduces semi-automated motion to high-rise formwork, using an integrated mobile control unit that allows operators to lift and position formwork systems safely and precisely from a single interface [16†L41-L47].
Looking further ahead, experts predict applications will be performed with less—or even no—human interaction. “The tools will be available to understand exactly how excavations behave, in turn this will enable us to interrogate real-time data and transform this into practical, accurate information” [13†L45-L50].
Expect to see smart props with load sensors, lightweight composite materials, and AI-assisted planning tools in the near future [19†L54-L55].
Practical Implications for Construction Professionals
Understanding the history of steel props isn’t merely academic—it has practical implications for every construction professional:
Choosing the right prop for your application
Basic adjustable steel props (Maxi props) – Suitable for general support, smaller loads, and straightforward applications
Multi props – Required for heavy loads, complex formwork, and demanding structural applications
Specialized systems (ringlock, tubular) – Best for large-scale industrial and infrastructure projects
Understanding safety requirements
Modern regulations—including OSHA standards in the US, EN standards in Europe, and local codes worldwide—establish minimum safety requirements that must be met. Using compliant, well-maintained steel props isn’t optional; it’s a legal and moral obligation.
Evaluating total cost of ownership
While premium steel props have higher upfront costs, their reusability (often 10-15 years or more), reduced maintenance requirements, and faster installation times typically deliver lower total cost of ownership compared to cheaper alternatives.
Planning for the future
As digital tools like BIM and real-time monitoring become standard, contractors who adopt these technologies early will have significant competitive advantages in efficiency, safety, and risk management.
Conclusion
The history of steel props is a story of continuous innovation driven by practical necessity. From the timber braces of 19th century London sewers to W.A. de Vigier’s revolutionary adjustable steel prop in 1935, from the brand that gave its name to an entire product category—Acrow—to today’s precision-engineered multi props, the evolution of temporary support systems has transformed construction.
Key milestones in this evolution include:
1860s – First documented ground shoring using timber in London
1890s – Steel sheet piling patented in the US
1931 – Steel props introduced in British mines, revolutionizing mining safety
1935 – W.A. de Vigier invents the adjustable steel prop
1936 – Acrow Limited founded in the UK
Post-WWII – Hydraulic shores, steel shields, and slide rail systems emerge
1990 – OSHA Subpart P drives safety innovation
2000s–present – Multi props, aluminum components, digital integration, and smart systems
Today’s multi props offer superior load capacity, precision adjustability, modular compatibility, and enhanced safety features that would astonish the miners who first demanded steel props in 1931. And the future promises even more: lightweight composite materials, real-time digital monitoring, AI-assisted planning, and ultimately, autonomous shoring systems.
Whether you’re pouring a residential concrete slab or supporting a massive infrastructure excavation, the steel props you use today carry forward over a century of engineering refinement—and the journey is far from over. As materials science advances and digital integration deepens, temporary support systems will continue to become safer, stronger, and more efficient, driving construction productivity forward for generations to come.
