On Deck

Success with design-build requires expertise from various construction disciplines and depends on the partnering among contractors, architects, engineers, specialty contractors and manufacturers. Collectively the team considers options, selects the best ones, coordinates design activities and mobilizes operations to make the process work. As a result, the steel industry is well positioned to contribute to the success of design-build projects.

Teamwork and involvement by steel specialty contractors and material suppliers during the design development process is what makes it work. Steel deck producers can play a complementary role in the design-build process and should be called upon to help design-build teams optimize solutions to meet the needs of specific projects.

The Speed Factor

Steel decking speeds the design-build process by accelerating construction. Deck is lightweight and manageable, fabricated off site, able to be installed efficiently and is adaptable to any structural frame. Erectors can select from no less than four different field connection methods, depending on structural performance needs and the selected deck profile. This equates to a structure that is built faster and released to other trades sooner.

When brought into the process early enough, deck producers can respond to the design-build team with a complement of services, including support in design development, engineering and manufacturing. Project management support can also help coordinate bundling, shipping schedules and installation procedures with fabricators and erectors. And steel deck can be used in a variety of applications with design-build.

From the Rooftops

Since the mid-20th century, steel deck has been commonly used in roofs covering commercial and manufacturing facilities and is an integral component in the roofs of structures in all market segments. More recently, steel roof deck is adding value to high-performance schools, transportation hubs and athletic facilities.

It’s a structural workhorse providing an all-season barrier to the elements. Consider that in a single application, steel roof deck may see forces ranging from say a 60-PSF wind uplift to a 60-PSF snowdrift. Steel decking’s structural performance is qualified by the AISI Specification for the Design of Cold-Formed Structural Members and documented in numerous tests and re-assurances from international code and hazard insurance agencies.

Producers are now responding to an industry in transition. Topping the list of challenges is sustainable design. Sustainability is an opportunity for roof deck producers to develop and enhance products that reduce labor and material demands, weigh less, install faster, improve the interior environment and lower life-cycle costs. Research and development efforts are in place to position the industry to meet growing demand.

With the emergence of green roof technology, high load capacity decks are best suited to sustain their additional weight without resorting to additional, closely spaced supports. Deep, long-span oriented profiles offer designers another way to handle increased load while enabling the freedom to open up spaces.

The integration of daylighting elements through roofs, such as skylights, is gaining in popularity. Case studies confirm natural lighting will positively impact student performance and the work environment while helping to reduce life-cycle energy costs. Related to steel decking, the process begins with carefully planning the position of the elements over the roof surface. Once determined, certain deck shapes can be outfitted with factory cut holes and reinforcements to retain structural integrity.

Steel deck’s multi-functional and aesthetic options range from bold, deep-fluted profiles to decks with curved or smooth cellular liner panels to the lineal plank look of the dovetail shape. A structural dynamo, many designers are leaving metal exposed instead of covering it with suspended ceilings.

Warranted, engineered paint coatings make deck exposure possible — environmental demand predicates coating performance. For example, coatings designed for an aggressive, damp natatorium environment are entirely different from those of a stadium sunscreen subjected to UV rays. Paints can also help regulate light reflectivity, another critical element in space design protocol.

Virtually all steel roof deck profiles are available with a sound control feature. Controlling sound is a proven method to enhance attention and has a calming influence in places where people congregate. Acoustical decks require the addition of perforations to the exposed interior surfaces of the deck profile. Sound energy is dissipated by acoustical insulation batts placed behind the perforations. The level of sound absorption is heavily dependent on the deck profile, perforation area and insulation properties. Other roofing components can vary performance slightly.

Cellular decks, consisting of a liner panel fixed to the bottom of a fluted deck profile, can be outfitted with removable panels to enable concealment of secondary sprinkler lines and conduit runs. Integrated support brackets are added between the deck sidewalls to support the service lines.

Designers of domed and serpentine structures and canopies can use hard curving techniques to eliminate residual forces exerted when walk-down methods are employed to induce curvature to an otherwise rigid deck profile. Typically this method will impact aesthetics as well.

On the Floor

Structures requiring non-combustible construction assemblies frequently specify traditional composite floor decks featuring web embossments that key to the concrete topping. Their use is widespread and generally well understood. The same can be said of concrete topped form decks placed over closely spaced supports, such as open web steel joists. Durable, fire and shear resistant composite floor systems are time tested.

Like roof decks, composite floor decks may be left exposed, and, when needed, contain similar sound absorbing features. Composite acoustical decks involving cellular liner panels and others outfitted with caps and plugs to keep wet concrete from contacting the insulation batts are available.

Reducing floor heights is significant when jurisdictions impose height restrictions to accommodate the limits of their fire-fighting equipment or to maintain a community’s visual appeal. This helps explain why low-profile composite deck systems have captured a larger portion of the mid-rise residential market as developers attempt to maximize the number of floors in a building. Because composite floor decks require shallow concrete depths to achieve their fire resistance ratings, they help reduce floor-to-floor height and provide an opportunity to shed a portion of the cost of expensive curtain walls and service risers that feed them.

Recent innovations include the development of low-profile, long-span composite floor decks capable of reaching spans up to 35 feet. Long-span floors provide flexibility to designers wishing to create wide-open spaces free of dropped filler beams. Advancements in low-profile composite beams coupled with long-span composite floor decks are also strengthening steel’s position in the design-build market.

Across the Bridge

Reinforced concrete bridge decks are built safer and completed sooner with stay-in-place steel forms. Gone are the hazards associated with the installation and stripping of conventional plywood forms while the section’s closed ends speed installation by eliminating end closure.

Bridge deck is formed from heavily galvanized steel sheet to enhance longevity. Advancements in polymer laminate coatings make bridge deck an excellent choice in aggressive environments like those over brackish waters or salted roadbeds.