Modern composite deck flooring is an innovative product that owes its development to the iterations of previous products, stretching back before World War II and continuing through today. From those early roots to the present, steel deck flooring has been a proven industry leader in structural strength, quality, value, and durability. The evolution of composite deck from its earliest form to the products you can buy today that will last for generations is interesting and worth tracing.
Prior to World War II: Holroib
Before the Second World War, developers commonly constructed concrete floors in steel buildings using reinforcing bars and temporary or permanent forms. While this was an effective method, it was also time-consuming, labor-intensive, and expensive. As a result, designers and contractors began looking for better options.
In response, Holorib began producing a metal deck with dovetail-shaped ribs spaced on 6” centers. Originally this product was manufactured as a steel roof deck, but Holorib inverted it to use as composite flooring. Although the product had significant limitations, the dovetail shape bonds steel deck to concrete very effectively and is still an advantage today.
The 1950s: Cofar and Q-Floor
Another company, Ganco, also sought to provide a better alternative to the reinforcing bars used prior to the war. It produced Cofar, which it advertised at the time as “reinforcement that forms.”
Cofar was built on two profiles that were popularly used as permanent metal forms for concrete floors. Cofar added transverse wires to these forms to create composite action and eliminate the need for positive reinforcement through reinforcing bars.
Although Holorib had a similar function, Cofar outperformed it because of the structural integrity inherent in its symmetrical shape. Cofar’s transverse wires did dual duty as temperature and shrinkage reinforcement, making it even faster and easier to install.
Cofar met a market need and was considered innovative when it was developed, but it didn’t stand the test of time. Ultimately, the dovetail profiles and later composite alternatives proved to be more efficient and effective.
As it turned out, the answer to steel deck flooring issues in the 1950s would be solved by roofing material. The H.H. Robertson Company developed standard steel roof deck profiles in thicknesses heavy enough so that the steel deck itself could carry the entire dead and live load of the floor. This innovation completely eliminated the need for positive reinforcement in the slab, so developers no longer needed composite action between the steel deck and overlying concrete. The company named this product Q-Floor and began the tradition of H.H. Robertson naming all of its steel deck profiles—with one notable exception—Q Deck.
Though this method is no longer used, at the time, Q Deck was so ubiquitous that it became synonymous with steel deck, the way Kleenex is synonymous with facial tissue. This was largely because the H.H. Robertson Company salesforce was a massive army that penetrated the market the way no other company could. Its sales team had members in every city, and they went to civil engineering schools to promote their products. This was when you couldn’t just look up a product on the internet, so in-person sales teams were the driving force behind selling products.
The 1960s: Hi-Bond and Q-Lock
The H.H. Robertson company used Q-Floor profiles that were typically 1-1/2” deep with ribs on 6” centers and 3” deep with ribs on 8” centers—standard steel roof deck profiles. Though not typical, the company also produced some profiles that were more than 3” deep. Robertson was the industry leader, but it did have competition—most notably Inland Steel, which later became Inland-Ryerson and still later Inryco. In the 1960s, it added composite action into its profiles. This brilliant innovation was achieved by rolling embossment into the steel deck, which bonded the deck to the overlying concrete the way embossments bond rebar to the concrete around it. Inland Steel named this product Hi-Bond.
Because it was a simple and inexpensive solution, other companies soon copied the concept, including Robertson, which named its product Q-Lock.
The 1970s: The Sears Tower
Along with composite steel deck flooring, other composite materials were also being used around this time. Developers were welding steel studs—shear connectors—to steel beams to create composite action between a beam and the concrete slab that it supported. As a result, developers needed new equipment that could weld studs to beams through the steel deck. This necessitated creating an entirely new steel deck profile that could fully develop the strength of the shear connectors. This new profile required a significant upfront investment in new tooling, which was much more expensive than it is today.
The existing products had incompatible profiles, and adjustments added extra weight and expense. Inland and Robertson were the first companies to create compatible profiles. The companies maintained rolling embossments but made the ribs wider for more effective shear connections. They also made symmetrical shapes that had a better strength-to-weight ratio and were 3” deep to achieve longer spans without shoring.
The primary difference in the Inland profile was that it was originally made with ribs spaced on 15” centers, while the Robertson one was made with ribs spaced on 12” centers. The Inland profile was used for the Sears Tower—now called the Willis Tower. Yet the Robertson profile—the QL-99—became the standard we still use today, both in 2” and 3” depths. These are now produced by many different manufacturers. Many of these later companies were able to enter the market as the price of production came down.
Over Seven Decades of Composite Steel Deck
Ultimately, the steel deck composite we use today owes its development to four prior advancements: dovetail profiles, transverse wire profiles, roof deck profiles with embossments, and the QL-99 equivalents—each evolutionary step addressing practical construction challenges and setting new standards in performance. Understanding this progression not only highlights the ingenuity that has driven the industry forward but also underscores why composite steel decking remains essential in modern construction—delivering unparalleled durability, structural integrity, and lasting value to builders and developers alike.