|
D-MAC Industries offers a wide variety of steel roof decks in order to meet the design requirements of virtually every commercial roof application.
The most efficient (highest strength-to-weight) and widely used inch-and-a-half deep steel roof deck is the Wide Rib Roof Deck in 22 gauge. Commonly known as Type B Roof Deck, the Wide Rib deck can support common gravity roof loads at spans varying from four to six feet. Longer spans and higher load resistance are achieved by utilizing a steel roof deck that is either deeper or heavier (made with a thicker gauge and therefore lower gauge number).
When strength of roofing materials is a concern, or when matching existing steel roof deck profiles that were commonly used before Type B/Wide Rib Roof Deck became prominent, an Intermediate Rib Roof Deck, or Narrow Rib Roof Deck may be required. Also known as Type F Roof Deck and Type A Roof Deck, respectively, these steel roof decks are also one-and-a-half inch deep and have ribs spaced at six-inches on center (referred to as six-inch pitch). Though both of these steel roof decks off er a lower strength to weight ratio , they provide more support for insulation board than the Type B/ Wide Rib. Type A, which is the oldest steel roof deck profile, was designed to provide support for the very weak insulating materials used back in the 1950’s and 60’s.
When large vertical loads are encountered, or spans are in excess of eight feet, the Deep Rib Roof Deck is the most economical steel roof deck. As with the design of structural beams, it is usually most economical to achieve increased bending resistance by utilizing deeper steel roof deck sections rather than increasing the material thickness of a shallower steel roof deck. Deep Rib/Type N Roof Deck is often used on building canopies because it can support the weight of roofing materials over spans common to such installations within deflecti on limits.
In addition to sustaining vertical loads, steel roof decks may also be fastened to the primary structure and to adjacent steel roof deck units, so that the steel roof deck itself becomes a diaphragm to transfer horizontal loading through the structure. This horizontal loading may be caused by wind or by seismic activity. The Steel Deck Institute publishes a Diaphragm Design Manual which details the design strength of various steel roof deck sections attached to the primary structure using a variety of fasteners, such as screws, welds, butt on-punches, and powder actuated fasteners, all applied in a variety of patterns and frequencies.
When exposed in the interior of a building, steel roof decks can function as a sound-deadening barrier when perforated webs are filled with insulation. This is referred to as Acoustical steel roof deck.
When a flat surface is desired, D-MAC Industries can supply Type B roof deck or Type N roof deck with a fl at sheet welded to the bottom of the corrugated deck sheet. This is commonly referred to as “plated roof deck” or “cellular roof deck”. When the plate is perforated and the cells of the steel roof deck are filled with insulat on for sound deadening, the resulting panel is referred to as “cellular acoustical roof deck.”
D-MAC Industries provides all steel roof decks with either a prime-painted, Galvanized, or galvanized and prime-painted finish. Since a steel roof deck is intended to be covered and protected from the elements throughout its service life, the deck coating primarily serves to protect the base metal during production, transportation, job-site storage, and erection. In less-severe climates, a prime-painted finish is usually very effective in providing this temporary protection. However, if transit or storage ti mes are long, or if the local environment is humid, a galvanized finish should be selected in order to achieve a higher level of corrosion resistance. Galvanized steel roof deck is available in either a G60 (0.6 oz/s.f. of zinc totaled over both sides of the sheet) or G90 coating. The relationship between coating weight and corrosion resistance is nearly linear. That is, a G90 coating provides one and a-half ti mes the corrosion protection of a G60 coating. Regardless of coating selection, steel roof deck must be properly stored on site in order to prevent excessive corrosion. One side of the roof deck bundle should be elevated so that moisture can escape with the help of gravity. The high side of the bundle should be covered loosely with a waterproof membrane or tarp.
The preceding overview of steel roof decks is just that. For more details on each specific roof deck profile offered by D-MAC, please click HERE. If you cannot find the information you are looking for online, please contact us via email or telephone at 1-800-878-3622. We look forward to the opportunity to serve you!
|
