Steel Roof Deck: What Are the Different Types?

Published: 06th May 2011
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The Wide Rib Roof Deck is the most popular steel roof deck and has the highest strength to weight ratio of all the steel roof decks. It is 22-gauge roof deck, most commonly called a Type B roof deck. The Wide R Roof Deck can handle a stress load at any span from four to six feet. In order to achieve greater strength you need a steel roof deck that has deeper ribs or a heavier gauge. A heavier gauge means getting a steel roof deck with a lower number.

If you have deck that was made before the inception of the Type - B/Wide Rib roof you may need to use a Narrow or Intermediate Rib Roof Deck to match it. These are known as the type- A roof deck and type - F roof decks, their ribs are spaced 6 in on center and are also the same in depth. This is called the six-inch pitch. They may be a little less than the strength to weight ratio, but they offer more support for insulation than the Type - B Wide Roof. The Type - A is the oldest of the steel roof decks. It was made in the 50's and 60's to handle the really weak insulation of that period

The Deep Rib Roof Deck is the most economical steel roof deck especially when you need a roof to handle large vertical loads or if you want it to span anything over 8ft. Just like structural beams, it has proven to be more economical to use deeper steel roof sections rather than increasing the material. This gives the roof more flexibility when it comes to handling vertical loads. Most canopied buildings utilize deep Rib/Type N roof decks simply because they do support more weight.

You can also fasten a steel roof deck to most existing primary structures or adjacent steel roof deck units. This makes the steel roof deck more like a diaphragm that is capable of transferring the horizontal load throughout the structure. Earthquakes or high winds can easily cause a horizontal load weight, which is why the Steel Roof Institute published a manual on diaphragm design.

The manual shows in detail how each type of steel roof deck sections can withstand pressures. They examine each using a variety of fasteners and horizontal weight loads. All so that the users of steel roof decks can choose one that will be beneficial in their region. Steel roof decks have evolved and are stronger than the roofs of our great grandparents, and even our grand parents. They are galvanized today for greater longevity. Learn more about them almost anywhere on the internet.


Mr. Steel travels North America giving presentations to professionals in the construction industry on metal decking and steel deck and their uses in construction. When not traveling for work, John enjoys vacationing in Hawaii where he enjoys the people, the culture and the fun activities.

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