Understanding Metal Form Deck vs. Composite Deck

Composite decks and form decks are two choices of metal deck options. Both can be used in a variety of applications, but how do you know which one is best suited for your needs?

In this guide, we will explain the key differences between these two products and potentially why the EOR specified a particular option for your application.

Metal Form Deck

This image shows a steel form deck

O’Donnell Metal Deck – Steel Form Deck

Steel form decking is the perfect solution for concrete floor slab construction because its permanent steel form eliminates any need for temporary wood forming, making it a fast, easy and efficient solution. And with proper design considerations, you can even eliminate shoring during the construction phase — steel form decking or non-composite deck takes up that role until the concrete cures.

Steel form deck pans are used to hold and form wet concrete as it cures in myriad applications such as stairways, foundations and mezzanine designs. 

They’re especially popular in applications where increased strength is not needed and cost savings are the main goal. The three most common types are 9/16-inch, 1-inch and 1.5-inch form deck, but ⅞-inch and 1 5/16-inch options are also available.


The lower the gauge number, the stronger the steel.


Steel deck profiles have different heights and spacing between ridges: 

  • The 9/16-inch form deck has a total panel thickness of 9/16 inches with ridges spaced at 2.5 inches on center. The panels are available in both 35-inch and 36-inch widths.
  • The 1-inch form deck is 1 inch thick with ridges spaced at 4 ½ inches on center. The panels are available in 36-inch widths.
  • The 1.5-inch form deck is 1.5 inches thick and the ridges are spaced at 6 inches on center. The panels are manufactured to cover 36 inches of floor space.


The standard finishes available on form deck are:

  • 9/16 inch: G-60
  • 1 inch: G-60 and G-90
  • 1.5 inches: G-60, G-90

Metal Composite Deck

This product image shows a metal composite deck

O’Donnell Metal Deck – Composite Deck Products

Composite decks are instantly recognizable by their steel deck embossments. The little indentations within the flutes of the profile allow for composite action between the metal and concrete slab — in this process the composite deck is the positive bending reinforcement for the slab.

After the concrete has hardened, steel deck embossments, rebar and slab design combine to form a composite section that is designed to hold up under load. This mixture of floor decking and concrete serves two purposes: to provide permanent stability and reinforcement. Therefore utilizing composite metal decking can actually boost the strength of your floor system in contrast to using form decks alone.

The EOR will commonly specific three options: 1.5-inch, 2-inch and 3-inch decks.


Just like steel form decks, the lower the gauge number, the stronger the steel is.1.5-inch, 2-inch and 3-inch composite deck panels are manufactured in 16-, 18-, 20- and 22-gauge thicknesses.


Composite deck profiles have different heights and spacing between ridges and can have a different arrangements of embossments.

  • 1.5-inch deck panels are 1.5 inches high, with ridges at 6 inches on center, and a coverage width of 36 inches.
  • 2-inch deck panels are 2 inches high, with indented ridges at 12 inches on center and a panel width of 36 inches.
  • 3-inch deck panels are 3 inches thick, with indented ridges at 12 inches on center and manufactured to cover 36 inches of floor space.


All three panel sizes are available in a G-60, G-90 and PTD finish.

When to Use Composite Deck vs. Form Deck

Deciding between composite and form deck for flooring requires considering their different characteristics.

Composite decks are superior because they add structural strength to your floors without adding extra weight. By combining the compression power of concrete and the tensile strength of steel, composite steel decks decrease material requirements while increasing design efficiency.

Form deck is an ideal choice for floor construction because it offers a cost-effective form to keep concrete slabs in place while they are being erected. In certain situations, utilizing form deck panels eliminates the necessity of expensive temporary deck shoring. Unlike other forms which bond with concrete and thus improve its load-bearing capacity, form deck only serves to support the poured material above it without increasing the strength of the whole system.

Discover Premier Form Deck and Composite Deck Products with O’Donnell Metal Deck

With a record that spans 35 years and over 15,000+ successful projects, O’Donnell Metal Deck is a trusted name in the industry. We provide superior quality products, professional support, expertise in product knowledge and rapid nationwide delivery.

Our form deck and composite deck products have been manufactured to meet the highest industry standards, and we carry all the required accessories and fasteners needed to complete your project on the first attempt! 

Contact us today for more information or to get a fast quote!