Form Metal Decking Guide Non Composite Steel Deck for Concrete Forms Sizes and Applications

Form Metal Decking Guide

Form metal decking, also known as non composite steel decking, is used as a permanent formwork system for concrete slabs. Unlike composite decking, it does not structurally bond with the concrete. Instead, it serves as a platform to support wet concrete during pouring and curing.

Form decking is widely used in construction projects where composite action is not required, such as slabs on grade, elevated slabs with independent reinforcement, and temporary or permanent formwork systems.

This guide covers everything you need to know about form metal decking, including types, sizes, gauges, applications, installation, and key differences from composite systems.

What Is Form Metal Decking

Form metal decking is a steel deck profile designed to act only as a form for concrete placement. It supports the weight of wet concrete and construction loads but does not contribute to the structural strength of the finished slab.

Key Characteristics of Form Decking

Non Composite Design

No embossments
No bonding with concrete

Function

Supports wet concrete
Acts as permanent formwork

Structural Role

Does not act as reinforcement
Concrete slab carries load independently

Differences Between Form Deck and Composite Deck

Form Deck

No composite action
No shear studs required
Simpler installation

Composite Deck

Bonds with concrete
Requires shear studs
Increases structural strength

Types of Form Metal Decking

Standard Form Deck

Features

Smooth surface
No embossments

Applications

Concrete formwork
Slabs with independent reinforcement

Galvanized Form Deck

Features

Zinc coated
Corrosion resistant

Applications

Outdoor or exposed environments

Painted Form Deck

Features

Pre painted finish

Applications

Exposed ceilings

Deep Form Deck

Features

Increased rib depth
Higher load capacity

Applications

Thicker slabs
Longer spans

Form Deck Sizes and Dimensions

Common Depths

1.5 inch
2 inch
3 inch

Standard Width

36 inch

Sheet Length

Custom cut
Typically 6 ft to 40 ft

Rib Design

Designed for load support during pouring

Gauges and Thickness

Common Gauges

22 gauge light duty
20 gauge standard
18 gauge heavy duty
16 gauge extra heavy duty

Gauge Selection

Based on span
Based on concrete weight
Based on construction loads

Materials Used

Galvanized Steel

Most common
Corrosion resistant

Galvalume Steel

Improved durability

Painted Steel

Used for exposed applications

Load Capacity and Span

Factors Affecting Performance

Deck thickness
Span between supports
Concrete thickness

Typical Span Applications

Short to medium spans
Temporary support conditions

Load Types

Wet concrete load
Construction loads
Worker and equipment loads

Concrete Systems Using Form Deck

Slabs on Grade

Used as temporary formwork

Elevated Slabs

Reinforced concrete slabs

Structural Slabs

Concrete carries all loads

Reinforcement in Concrete

Typical Reinforcement

Rebar
Wire mesh

Function

Provides structural strength
Independent of deck

Applications of Form Metal Decking

Commercial Buildings

Concrete floor systems

Industrial Construction

Heavy duty slabs

Infrastructure Projects

Bridges
Public works

Residential Construction

Multi unit developments

Installation Process

Step by Step

Place deck sheets
Align panels
Fasten to structure
Install reinforcement
Pour concrete

Fastening Methods

Welding
Screws
Mechanical fasteners

Installation Best Practices

Proper Support Spacing

Prevents deflection

Secure Fastening

Maintains stability

Correct Reinforcement Placement

Ensures slab performance

Advantages of Form Metal Decking

Simple system
Lower cost than composite deck
No shear studs required
Flexible design options
Easy installation

Limitations

No structural contribution after curing
Requires full concrete reinforcement
Limited span compared to composite systems

Common Problems and Solutions

Excessive Deflection During Pour

Cause

Insufficient gauge

Solution

Increase thickness or reduce span

Deck Deformation

Cause

Overloading

Solution

Follow load limits

Concrete Cracking

Cause

Poor reinforcement design

Solution

Use proper reinforcement

Cost of Form Metal Decking

Cost Factors

Steel gauge
Span requirements
Project size

General Cost Trends

Lower cost than composite decking
Increased cost with thicker gauges

How to Choose Form Metal Decking

Consider Structural Design

Determine if composite action is required

Consider Load Conditions

Wet concrete weight

Consider Span

Match deck to support spacing

Consider Budget

Lower cost solution

FAQ Form Metal Decking

What is form metal decking used for
It is used as a form for pouring concrete

Does form deck support structural loads
No the concrete slab carries the load

Do you need shear studs
No

What sizes are available
Typically 1.5 inch to 3 inch depths

What gauge is used
Typically 22 to 16 gauge

Conclusion

Form metal decking provides a simple and cost effective solution for concrete formwork in construction projects where composite action is not required. It allows for faster construction while maintaining flexibility in structural design.

By understanding its role, limitations, and installation requirements, contractors and engineers can use form decking effectively in a wide range of applications.