Steel deck is a type of cold-formed corrugated metal most commonly used to support the insulating membrane of a roof. It is created by stamping and pressing traditional sheet steel into the desired shape, which, upon installation, provides extra support between the roof’s joists and beams. Many different manufacturers sell their own trademarked brand of steel deck, although the most important qualities that builders tend to look for remain fairly consistent across all brands.
Strength and Versatility
Steel deck is designed to have a high strength-to-weight ratio for handling heavy loads of concrete and membrane while still remaining versatile. The width and depth of the ribs in each piece of steel deck are crucial to providing lateral force distribution throughout the structure's vertical force resisting systems. The four common rib types are narrow, intermediate, wide and deep. The first three each feature rib depths of about 1 1/2 inches and are produced with 30- to 36-inch cover widths, while the deep rib is about 3 to 7 inches tall with 24-inch cover widths and is mostly used when longer spans are required between support beams. Builders can choose from a wide variety of thicknesses as well, although typically no thinner than 0.76mm.
Steel deck is available in a number of specialized designs, including composite, cellular and acoustic. Composite deck is made with mechanical embossing in the webs that creates a structural bond between the steel deck and the concrete. The composite action lets the steel deck act as a pliable reinforcement for the slab, eliminating the need for rebar and reducing the costs of labor and materials. Cellular deck includes a flat liner panel that provides the same strength as traditional corrugated steel decks with a flat appearance on its underside instead of the typical ribbed look. And acoustic deck is produced with fiberglass insulation batts that absorb sound waves and prevent echoing.
Steel deck can be erected in and can withstand nearly all types of weather conditions, from intense sun and humidity to rain, sleet, frost and snow. The galvanized steel used to make steel deck features a rust-resistant zinc, zinc-iron or zinc-aluminum alloy coating that usually meets requirements for fire resistance as defined by Underwriters Laboratories. In addition, steel deck is a low-cost material with a long life cycle that provides high economic value, is relatively easy to maintain and provides an aesthetically pleasing appearance if left exposed.
Steel Deck Design Tools
A number of computer-based tools are available specifically to assist builders with installing steel deck. Maximum-span calculators figure out the longest unshored span a specific piece of steel deck can withstand when used with various structural concrete slabs. Diaphragm-interaction calculators determine shear resistance and uplift pressures. Certain programs also create tables that calculate the slab capacities in structural concrete by factoring deck yield, gauge and concrete density. In addition, professional design guides on steel deck contain lists of standard steel properties, galvanizing designations and conversion tables between U.S. standard units and metric units.
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