Galvanised Metal Decking Guide Steel Deck Types Coatings Sizes Gauges and Corrosion Protection

Galvanised Metal Decking Guide

Galvanised metal decking is the most widely used material for steel decking systems in North America and globally. It offers a combination of structural performance, corrosion resistance, and cost efficiency, making it the standard choice for commercial, industrial, and infrastructure projects.

From composite floor systems to roof decking and mezzanine structures, galvanised steel decking delivers long term durability in a wide range of environments.

This guide provides a full technical and commercial overview of galvanised metal decking, including coatings, types, sizes, gauges, performance, applications, and installation.

What Is Galvanised Metal Decking

Galvanised metal decking is steel decking coated with a layer of zinc to protect against corrosion. The galvanisation process creates a protective barrier that extends the life of the steel, even in harsh environments.

How Galvanisation Works

Zinc Coating Protection

Zinc acts as a barrier against moisture
Prevents rust formation

Sacrificial Protection

Zinc corrodes before steel
Protects exposed areas

Coating Methods

Hot dip galvanising
Continuous galvanised coil coating

Types of Galvanised Metal Decking

Galvanised Composite Decking

Profile Details

Embossed ribs
Designed for concrete bonding

Applications

Concrete floor systems
Multi story buildings

Galvanised Roof Decking

Profile Details

B deck and N deck profiles
Designed for roofing systems

Applications

Commercial roofs
Industrial buildings

Galvanised Non Composite Decking

Profile Details

Structural steel deck
Used without concrete

Applications

Mezzanine floors
Platforms

Galvanised Corrugated Decking

Profile Details

Wave profile
Lightweight

Applications

Agricultural buildings
Light duty roofing

Galvanised Deck Sizes and Dimensions

Deck Depth

1.5 inch standard deck
2 inch intermediate deck
3 inch deep deck

Sheet Width

Typically 24 inch to 36 inch

Sheet Length

Custom cut
Typically 6 ft to 40 ft

Rib Profile

Designed for strength and load capacity

Gauges and Thickness

Common Gauges

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

Thickness Selection

Based on span
Based on load requirements
Based on environmental exposure

Galvanisation Coating Standards

Common Coating Levels

G60 moderate protection
G90 standard protection
G115 heavy protection

Coating Selection

Interior environments G60
Exterior environments G90
Harsh environments G115 or higher

Materials and Finishes

Standard Galvanised Steel

Zinc coated steel
Most common option

Galvalume Coated Steel

Aluminum zinc coating
Enhanced corrosion resistance

Painted Galvanised Steel

Additional coating for aesthetics
Extra protection

Corrosion Resistance and Durability

Environmental Performance

Performs well in dry and moderate environments
Suitable for most commercial and industrial applications

High Risk Environments

Coastal areas
Chemical exposure
High humidity

Protection Strategies

Use higher coating levels
Apply additional coatings
Ensure proper drainage

Load Capacity and Structural Performance

Load Types

Dead load
Live load
Concrete load
Environmental loads

Structural Performance

High strength to weight ratio
Suitable for floor and roof systems

Span Capabilities

Depends on deck depth and gauge
Deep profiles allow longer spans

Applications of Galvanised Metal Decking

Commercial Buildings

Office floors
Retail structures

Industrial Facilities

Factories
Warehouses

Roofing Systems

Roof deck applications

Infrastructure Projects

Bridges
Platforms

Agricultural Buildings

Storage facilities

Installation Process

Step by Step

Deck Placement

Install on structural frame
Align panels

Fastening

Weld or screw to supports
Secure side laps

Composite Systems

Install shear studs
Pour concrete

Roof Systems

Install insulation and membrane

Installation Best Practices

Protect Coating

Avoid damage during installation

Secure Fastening

Prevent movement

Proper Storage

Keep materials dry before installation

Advantages of Galvanised Metal Decking

Excellent corrosion resistance
Long service life
Cost effective
Widely available
Suitable for most environments

Limitations

Limited protection in extreme environments
May require additional coatings
Coating damage can lead to corrosion

Common Problems and Solutions

White Rust

Cause

Moisture trapped during storage

Solution

Store in dry conditions

Coating Damage

Cause

Handling or installation damage

Solution

Use protective methods and touch up coatings

Corrosion in Harsh Environments

Cause

Insufficient coating

Solution

Use higher coating levels or alternative materials

Cost of Galvanised Metal Decking

Cost Factors

Coating thickness
Deck type
Gauge thickness
Project size

General Cost Trends

Cost effective compared to other materials
Slight increase for higher coating levels

How to Choose Galvanised Metal Decking

Consider Environment

Select appropriate coating level

Consider Application

Floor or roof system

Consider Load Requirements

Structural loads

Consider Budget

Balance cost and durability

FAQ Galvanised Metal Decking

What is galvanised metal decking
It is steel decking coated with zinc for corrosion protection

What coating is best
G90 is standard for most applications

Can it be used outdoors
Yes with proper coating selection

What gauges are available
Typically 22 to 16 gauge

How long does it last
Depends on environment and coating level

Conclusion

Galvanised metal decking is the industry standard for structural decking systems due to its durability, corrosion resistance, and cost efficiency. It is suitable for a wide range of applications from floors to roofing systems.

Selecting the correct coating, gauge, and installation method ensures long term performance and reliability in any project.