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Metal Decking for Concrete | What is it Used for?

  • November 10, 2023

Think about the benefits of adding the strength and sustainability of steel to that of concrete for your next commercial project. 

How is this possible?

Metal decking for concrete is an alternative to traditional wood forms. Often, these metal panels are a necessity, such as with elevated floors. 

This article will provide an in-depth view on the aspects of metal decking and what you need to know before you include it in your next project. 

What is Metal Decking?

Metal decking is a versatile building material that can be used for various applications, including roofs, floors, and walls. 

It’s made from thin sheets of metal formed into a series of ribs or flutes. The ribs provide strength and support, while the flutes create a lightweight, open-web structure.

These deck panels can create a strong and durable surface, acting as a floor deck for concrete to be poured onto.

Types of Metal Decking

Several types of steel decks can be used to support your concrete slab. Each type has its use, but the first on the list is the most popular for good reason. 


Composite steel decking can be bought in a variety of sizes. Formlok, a famous decking supplier, offers composite decking in sizes of 1.5”, 2”, and 3”. 

The size measures the depth of the ribs. The most common, 1.5”, is known simply as B deck. If you need a long-span metal decking panel, you’ll want to choose the deeper sizes of 2” or 3.”

Metal deck products also come in a variety of steel gauges. The gauge of a metal panel is a measurement of the thickness. Deeper deck profiles from the lower steel gauges will result in more robust concrete slabs. However, only massive projects require the deepest decks and gauges. 

Composite metal decking is the top choice for most contractors because it increases the floor’s strength without adding extra weight.

The embossments in the steel sheets bond with the concrete as it dries. In effect, using both the strength of structural steel and concrete creates one extremely durable concrete floor. 


Cellular metal floor decking contains a piece of flat metal under the flutes to create cells. These cells are used to run electrical or plumbing under the floor, keeping them protected from the elements. 

This type of metal decking can be used for a roof deck or floor deck, but is most often applied to acoustical floor systems. Cellular is reserved for these uses because it’s too costly for anything else.


This slim profile sheet metal is rarely used as a steel floor deck because it simply supports the concrete and will not increase the strength of the floor. Steel-form decking is often used for the building of metal roofs. 

These are non-composite deck systems with two products available: Shallow Vercor and Deep Vercor.

How to Choose the Right Metal Decking for Your Project

What type of metal decking you should use for your project depends on many factors like the:

  • Type of concrete that will be poured on the decking
  • Load the decking will need to support
  • Length of the span needing to be covered
  • Climate in which the decking will be used
  • Budget for the project

Regarding engineering standards, the American National Standards Institute and Steel Deck Institute worked together to create a guide for professionals to follow concerning the gauges and thickness of panels and more. 

Why Use Composite Metal Decking for Concrete?

Composite metal decking is the best type of metal decking, period.

While other form decking can support heavy concrete pours, composite decking takes things one step further. Its structure, in effect, fuses the steel deck with the concrete, creating a concrete slab stronger than any other. 


Since the panels are precut and lightweight, minimal crane use is needed to place the forms before pouring concrete. In fact, the system is so fast that one team can install about 400 sq meters of composite decking per day.


Once installed, it provides a safe canopy for the workers below, minimizing the chances of being hurt by falling material or equipment. 

These panels also provide a strong platform for the workers above. Having the composite decking installed prevents people from having to walk carefully across steel joists to get where they need to go.  

Weight Reduction

Due to the amount of strength created by a composite decking system,  less concrete is needed to reach the load-bearing capacity listed in the specs. 

Less concrete translates into less weight, reducing the load on the entire structure. It also means reduced material costs. 


Composite decking results in much stronger slabs than the alternatives when constructed to the correct specs. It can act as a lateral restraint for beams and increase wind load resistance with fewer columns needed.

Shallow Construction

Since composite flooring needs less concrete, it results in thinner slabs. These thinner floors create a smaller story height. With each story taking up less vertical space, this will save the height of the entire building.


Both steel and concrete, the two materials used to create a composite floor deck, are considered sustainable building products. Steel is 100% recyclable, infinitely, making it incredibly sustainable. Concrete has many long-lasting properties as well. 

Read more: 11 Ways to Achieve Concrete Sustainability

How Much Does Metal Decking Cost?

The cost of a metal decking project is dependent on many factors, fluctuating with market value:

  • Current price of steel
  • Size of the job
    • How many square feet does the slab need to cover?
    • What about slab thickness? 
  • Depth and gauge of your metal decking 
  • Finishes
  • Delivery and shipping

How to Install Metal Decking

The construction team must follow a set process of installing metal decking in order to create a durable and sustainable structure, with each composite deck doing its job. 

1. Follow Specs

Each project will come complete with the engineer’s metal decking specifications.  The team must be familiar with and follow these specs to ensure the job is a success.

This document will not only provide you with the basic instructions and practices for installation, but will also give you the materials list needed so you can order all necessary items. 

2. Lay Out Metal Decking

Once you have all your metal decking in their correct placements, you’ll need to connect each sheet using a punch tool. Proper alignment is crucial to secure the sheets without leaving any cracks that can lead to corrosion or defects. 

3. Fasten the Panels to the Structure

Regarding the fasteners used to connect the panels to the structure, you have three choices:

Self-Drilling Screws

A screw gun is needed to install these into the frame. There are hand-held screw guns, but you’ll want to use a stand-up version for larger jobs. This option is most commonly used for roof decks, not flooring. 


Welding is a popular choice because it creates a stronger bond, but it’s the slower fastening option. Plug welds or puddle welds can be used.

Power-Driven Fasteners

Power-driven fasteners are one of the most popular. Installing them is fast and easy. It uses a tool with pistons that ram a pin into the decking. 

Whichever fastening option you choose, attach the metal decking first, then the side laps. Fastening the deck first ensures it stays in place and doesn’t shift when you connect the side laps. 

4. Install Reinforcements

Steel mesh and rebar are attached to the decking to amplify the strength of the concrete slab. These reinforcements are installed attaching the steel deck to the beam below and at the top section of the pour. 

5. Pour Concrete

The decking is now ready for the concrete to be poured. This step has some variables to consider, such as what concrete you need. 

With your chosen concrete, you can begin to pour this over the decking. Proper care must be taken not to overload one section and ensure the pour is even. Once all the concrete is poured and leveled, it must cure and dry.

Types of Concrete

One of the main variables in a pour is the type of concrete you choose. 

Your first choice is whether to use structural or nonstructural insulating concrete. 

Structural concrete is a mix of cement, aggregates, and water. It adds strength to the structure. Nonstructural insulating concrete is a mix of cement, vermiculite, and water. It provides insulation and is added in two layers with an insulating board in between. 

Structural concrete is often used on composite metal decking, and nonstructural concrete is for non-composite metal decking.

Next, you need to choose between normal or lightweight concrete. The difference between the two is the aggregates mixed in. Normal-weight concrete contains crushed stone, while lightweight concrete contains clay or shale. 

Learn more: Structural Concrete: What It Is, How It Works + Comparisons


Hopefully, after reading this article, you’ve gained the knowledge you need to decide if metal decking is what your project needs.  

If you are interested in building a project that requires metal decking, contact FMP Construction. They have the know-how, machinery, and experience necessary to install your metal decking project correctly.

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