What’s the difference between BMT and TCT?

by | Sep 5, 2023 | Shed Building, Shed Construction, Sheds garages carports | 0 comments

When constructing a steel shed, it’s imperative to have absolute confidence in its strength, durability, and engineering. 

In the steel cladding industry, there are two critical terms often used to describe the material’s properties: Base Metal Thickness (BMT) and Total Coated Thickness (TCT). These measurements are distinct but sometimes confused, and it’s essential to use them correctly to ensure the quality of your shed.

Base Metal Thickness (BMT)

Base Metal Thickness (BMT) is used to calculate the strength of steel cladding before any coatings or paint layers are applied. BMT is particularly useful for design calculations and structural considerations.

Total Coated Thickness (TCT)

Total Coated Thickness (TCT) accounts for both the base metal and any additional metallic coating layers, including hot-dip galvanization for corrosion resistance. To calculate TCT, simply add together the thickness of the base metal and each layer of alloy coating, paint, and primer. Unlike BMT, TCT doesn’t specify the core steel’s strength.

Choosing Between BMT and TCT

Both BMT and TCT measurements are similar, with only a slight difference in thickness. BMT represents the core strength of the steel, while TCT considers all protective layers, such as primer and paint. Neither measurement is inherently better than the other; they serve different purposes.

Bluescope list their available BMT and TCT together to avoid confusion and misconceptions.

Implications for Shed Quotes

When you’re planning to build a steel shed, it’s likely you’ll collect quotes from various suppliers and manufacturers to find the best price. It’s crucial to understand the cladding specified in each quote and whether the shed will be constructed using BMT or TCT quoted cladding.

During the quote comparison process, ensure that you’re comparing apples to apples. Check if the quotes are for the same thickness of sheeting, i.e., BMT with BMT and/or TCT with TCT. Failing to do so might lead to misconceptions about the product’s quality. Some companies may use thinner TCT grades than others, potentially increasing the risk of damage and wear-and-tear over time. Just because a company specifies a particular TCT measurement doesn’t necessarily reflect the product’s strength accurately.

Due to the distinctions between BMT and TCT measurements, it’s challenging to make direct comparisons between quotes that use different measurements. Therefore, it’s advisable to thoroughly scrutinize your shed quotes to ensure a clear understanding of what you’re investing in.