Know What You Are Buying
When buying roofing sheets, many customers ask one question:
“How much is the price or how many millimetres is the sheet?”
But the number alone does not tell the complete story.
A roofing sheet can be described using several important specifications, including Base Metal Thickness (BMT) , Total Coated Thickness (TCT) , metallic coating, steel grade, profile, and applicable product standards.
At Awa Roofing, we believe customers should understand what they are buying—not simply compare prices or thickness numbers.
BMT vs. TCT : What Is the Difference?
BMT — Base Metal Thickness
BMT means Base Metal Thickness.
It refers to the thickness of the steel substrate before the metallic coating is applied.
For example, when we specify an Awa Roofing product as:
0.50 mm BMT
we are referring to 0.50 mm of base steel.
BMT is therefore an important specification when comparing the actual steel substrate used in different roofing products.
TCT — Total Coated Thickness
TCT means Total Coated Thickness.
It refers to the thickness of the finished coated material, including the steel substrate and the applicable coating layers.
Therefore, BMT and TCT are not the same measurement.
For example:
BMT = thickness of the steel substrate
TCT = steel substrate + coating layers
This is why customers should always ask whether a quoted thickness is BMT or TCT before comparing different roofing products.
What Does AZ150 Mean?
Another important specification is the metallic coating.
For example, Awa Roofing uses AZ150 coated steel for specified products.
AZ150 is a coating designation. It does not mean 0.15 mm steel thickness.
The “150” refers to the specified total metallic coating mass under the applicable product specification, expressed in grams per square metre (g/m²).
The metallic coating provides protection to the underlying steel and contributes to the product’s durability and corrosion-resistance performance.
Therefore:
« 0.50 mm BMT and AZ150 describe two different characteristics of the product.»
The first describes the base steel thickness.
The second describes the metallic coating specification.
Why Does Steel Thickness Matter?
The steel substrate is an important part of a roofing sheet’s mechanical performance.
However, thickness should not be considered in isolation.
A quality roofing product also depends on factors such as:
• Base metal thickness
• Steel grade
• Metallic coating
• Profile and geometry
• Manufacturing quality
• Dimensional accuracy
• Installation method
• Environmental exposure
• Applicable product standards
A thicker sheet is not automatically the right product for every application, and a lower price does not necessarily represent better value.
The appropriate specification depends on the intended application and the conditions in which the roof will be used.
What Should Customers Ask Before Buying Roofing Sheets?
Before purchasing roofing sheets, we encourage customers to ask:
1. What is the BMT?
Is the quoted thickness the actual base metal thickness?
2. What is the TCT?
Does the stated thickness include the coating?
3. What is the metallic coating?
For example, is the product AZ100, AZ150, or another specified coating?
4. What is the steel grade?
Different steel grades have different mechanical properties and applications.
5. What profile am I buying?
The profile and geometry of a roofing sheet are also important to its application and performance.
6. What standard or specification does the product follow?
A proper product specification should identify the relevant technical standard.
7. What documentation supports the specification?
Where applicable, customers should be able to request relevant product or quality documentation.
Awa Roofing’s Approach to Transparency
At Awa Roofing , we believe roofing materials should be described clearly and honestly.
That means we do not want customers to judge a roofing sheet simply by a number written on a quotation.
We want customers to understand:
▪︎ What is the base steel thickness?
▪︎ What is the coating?
▪︎ What is the steel grade?
▪︎ What is the finished thickness?
▪︎ What application is the product designed for?
▪︎ What documentation supports the specification?
Our goal is to make technical information easier for customers to understand so they can make informed purchasing decisions.
Our Example: Awa AZ150 — 0.50 mm BMT
For our specified AZ150 product, the specification should be communicated clearly as:
Product: Awa AZ150 Roofing Sheet
Base Metal Thickness: 0.50 mm BMT
Metallic Coating: AZ150
TCT: As specified and verified for the product
Steel Grade: As specified for the product
Profile: As selected for the application
The exact technical specification should always be verified against the applicable product documentation.
Don’t Compare Roofing Sheets by Price Alone
Two roofing sheets may appear similar but have different specifications.
When comparing products, don’t ask only:
«“How much is one sheet?”»
Also ask:
«“What exactly am I getting?”»
Understanding the BMT , TCT , coating, steel grade, profile and applicable specification gives you a better basis for comparing roofing products.
At Awa Roofing, we believe an informed customer is a better customer.
Know the specification. Understand the material. Make an informed choice.
Awa Roofing — where every roof tells a story.
"Know What You Are Buying When buying roofing sheets, many"
