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Floor Deck vs. Roof Deck: What's the Difference?
Robert Rubio

By: Robert Rubio on October 24th, 2019

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Floor Deck vs. Roof Deck: What's the Difference?

Metal Deck

Metal Decking is manufactured in a few different forms. The two most commonly used are Composite Metal Floor Deck and Non-Composite Metal Roof Deck. It is important to know the difference when you go to purchase, so that you order the correct type.

Composite Metal Floor Deck

Non-Composite Metal Roof Deck






Shown above is Type B-Formlok Shown above is Type HSB-36

Distinguishing between Composite Floor Deck & Non-Composite Roof Deck is particularly important because some panels share the same profile and have identical dimensions such as HSB-36 and B-Formlok™(both types shown above). The only thing that differentiates them is the embossment pattern. The B-Formlok is manufactured with an embossment pattern, while HSB-36 is smooth with no embossment pattern.


Metal Floor Deck

Metal Floor Deck is oftentimes referred to as composite metal deck or composite metal floor deck. Composite Metal Floor Deck is meant to have concrete poured on it.


Composite is the combination of 2 or more distinct substances to create a solid material. In this case, we are referring to the metal deck and the concrete slab. They each have different physical characteristics and when they combine they create a composite system.


In order to create an effective composite slab, the metal floor deck is manufactured with an embossment pattern. The trade name for this embossment pattern is called Formlok™, which is manufactured by Verco Decking, Inc. It is manufactured into the vertical side of the decking. The embossment pattern gives the concrete something to attach and bind to.


Composite Floor Deck is made up of different profile types, below are the types manufactured by Verco Decking.


Composite Metal Floor Deck is used as a floor deck. The decking and concrete are used to provide an optimal vertical load capacity. It is made in different profile types, each with different diaphragm strength and unshored span tables which is stronger than the sum of the parts.


Metal Roof Deck


Non-Composite Metal Roof Deck isn’t intended for concrete. It is a smooth panel, with no embossment pattern. It is a structural roof deck that provides both diaphragm shear and vertical load capacity. As with the Composite Floor Deck, there are different profile types that each provide different diaphragm strength.


Non-Composite Roof Deck is made up of different profile types, below are the types manufactured by Verco Decking.


Non-Composite Metal Roof Deck is commonly used for roof decking on commercial buildings where they put rigid board insulation on top of it. On top of the rigid board insulation, they put built-up roofing.

Another use that is quite common is roofing on a canopy or steel building even though this material is not intended for that purpose, people put down type HSB-36Ⓡ and use that as the actual finished product for the roof. This was never intended to be used as stand alone roofing, but it is more common than you'd think. We do not recommend it to be used as stand alone roofing.

Some other ways that we have seen roof deck used are:

  • Siding, where roof deck is put in vertical condition to close off a wall.
  • Gates & fencing used in either horizontal or vertical position depending on how the owner wants the finished product to look.
  • Trash gates or roof covers for dumpster areas (used to prevent rainwater runoff)
  • Platform in movie theaters with the luxury reclining seating. Platforms have to be built up to accommodate this new type of seating and are usually done with metal roof deck underneath.

Roof Deck or Floor Deck?

When placing an order for Metal Deck it is important to let your sales rep know which type you need. Some profiles are made as both a Non-Composite Roof Deck and a Composite Floor Deck, which is why it is important to let your sales rep know which type you will need. Ordering Type B-deck or type N-deck isn’t enough information since both are made as a roof and floor deck. It is not uncommon to call out for type B-deck and the default is to sell roof deck since Formlok was not specified. This can cause huge problems if the plans specified B-Formlok.

Now that you understand the key differences between composite and non-composite decking and what each is used for you are ready to get pricing. Our sales reps have decades of experience with metal decking and would be happy to assist you. For more information on different types or you are ready to purchase please contact a sales rep today.


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About Robert Rubio

Robert Rubio is the President of Western Deck & Steel Erection. He has been in the steel construction industry since 1970 and is a Journeyman Local 433 Iron Worker.