Crew Leveling Concrete Mezzanine Floor

What is Form Deck?

Author Headshot - Charles
Nov 30, 2022

Form deck is used extensively in floor construction because it provides an economical solution to shoring and supporting the weight of a concrete floor in industrial building construction.

With a number of varieties available, it is important to understand what type of form decking is best suited to your site project, and this article will outline everything you need to know.

When it comes to concrete floor construction, form deck is an essential component in just about every site project. It provides an easy-to-install and inexpensive concrete form solution for multistory steel frame constructions. 

Where Is Form Deck Used?

Crew Leveling Concrete Mezzanine Floor

Form Deck is primarily used for flooring to support the weight of concrete that is poured over it to create a new floor level. It provides temporary shoring for wet concrete while it cures.

Unlike a composite floor—using B Deck with plywood—a concrete floor offers rock-solid stability and durability.

Form deck is available in various depths generally ranging from half an inch to an inch and a half. The deeper the panel, the stronger it is. This will then affect how thick a concrete slab it can support, usually between three and six inches. This will vary depending on the spacing of steel supports for the metal decking and the load requirements of the concrete slab.

How is Form Deck Made?

Unloading Decking Roll Form Machine

Much like most other types of metal decking, Form Deck is made using a steel deck roll forming machine. This draws steel of a predetermined gauge from a large coil through a sequence of 25-30 dyes to create the characteristic ridges and sidelap. 

This method of cold-forming is performed over such a large number of dies to ensure maximum strength while creating a shape that further increases its shear strength and load capacity while being lightweight.

What Are Different Kinds of Form Deck?

Decking Stack

As with all types of metal decking, there are a number of variants to suit different requirements. Form deck is no exception and there are some specific instances where specific characteristics will be necessary.

Gauge (Thickness)

Gauge is the unit of measurement that indicates the thickness of the metal decking. A lower number means a thicker and therefore heavier sheet, and a higher number is thinner and lighter. 

Because Form Deck is used to support wet concrete and not as a composite, it is usually manufactured in a lighter gauge (20-26 gauge) and the most common variants are 20 and 22 gauge.


Galvanized White Bottom Comparison

Unlike other forms of metal decking, it is advised to always use form deck with a galvanized finish to avoid premature rusting. White or gray paint can also be applied to provide a protective layer during construction or to provide an aesthetic finish, but paint should never be used in place of galvanizing.

The most common type of galvanizing for Form Deck is G30 which has 0.3 ounces of zinc per square foot. 


Form decking is supported by steel structural supports usually no more than five feet apart. If this distance is larger, sidelap screws are recommended to increase shear strength.

Sheet Length

In most cases, Form Deck is available as pre-cut sheets of between 10 and twenty-five feet, but it can be custom ordered to specific length up to 35 feet on

You can use a metal deck calculator to get a good idea of how much your project will cost.

Where Do I Buy Form Deck?

Structural Deck Loading

There are many local suppliers of form deck across the United States that have pre-cut sheets and a variety of finishes like those mentioned above. 

PWI purchases form deck from Structural Deck because they offer custom sheet lengths and 24 hour turnaround times.

They offer local pick-up from their Nappanee, Indiana location but also deliver to Indiana, Ohio, Michigan, Illinois, and southeastern Wisconsin.

Regardless of the size of your construction project, is your go-to metal decking supplier.