Why Layer FR Clothing?

You might think that a single-layer AR / FR garment with an arc rating above the potential incident energy level is the best way to protect yourself while performing high-risk work. While these garments are effective, two lightweight AR / FR layers typically have a higher arc rating than one layer at twice the weight. This is because when you layer two garments, an air gap is created, often boosting the protection value.

Another key benefit of layering is comfort. Put simply, wearing multiple lightweight layers of fabric can allow for greater range of motion and breathability than heavier garments. Increased comfort contributes to both compliance and overall safety—the more comfortable your garments are, the more likely you are to wear them and the less restricted you’ll feel while performing tasks.

How AR / FR Garment Layering Works

CAT 2 and higher protection can be achieved through layering various AR / FR base layers like undergarments, mid-layers like shirts, sweatshirts, and pants, and outer layers like jackets, coveralls, and more.

To determine the protection value of two layered garments, you might think you can simply add the arc rating of each item to determine the total calorie rating, but this is not the case. A 4 cal/cm² base layer and an 8 cal/cm² outer layer, for example, do not necessarily equate to 12 cal/cm² of protection. Remember: air gaps between layers can add calories to the arc rating, increasing protection.

Both ASTM F1959 and NFPA 70E state that you cannot merely add together the arc ratings of single layers to arrive at the arc rating of the layered system. This is why it’s critical to rely on existing test data to confirm that the two AR / FR fabrics you plan to layer have been tested together in the same configuration in which they will be worn.

Quick AR / FR Garment Layering Tips

When thinking about layering to reach a higher protection levels like 20 cal/cm² and above, consider these factors:

• Most pants typically fall within the 10–18 cal/cm² range and most shirts fall within 8–10 cal/cm², so you need added protection on both the top and bottom to reach this arc rating.
• A standard AR / FR base layer top and bottom with coveralls is one such way to achieve a 20 cal/cm² or higher protection level.
• Only AR / FR base layers count toward the total protection value of the layered system.

Note: For mid-level CAT 2 requirements, like 10–15 cal/cm², you may only need an added layer on top to reach the necessary arc rating if your pants already fall within this range.

Layer Smarter, Not Harder

Tyndale makes it simple for our customers to determine the total protective value of two layered AR / FR garments with our mobile app layering tool, which provides specific layering data for the garments we sell. It’s the easiest way to ensure you’re adequately protected.

More information on this tool—including a video walkthrough—can be found here: https://tyndaleusa.com/fr-safety-resources/tools/layering-tool/.