Cold weather clothing layering: Why thicker isn’t better

Responding is Michael Batson, military and professional workwear global product director, Polartec, Lawrence, MA.

Layering protective clothing during winter is a tried-and-true way to maximize your comfort when working outdoors or in an unconditioned environment. Layering also allows you to make quick adjustments based on your activity level and changes in the weather to stay comfortable and compliant.

Selecting the winter clothing system

In the performance outdoor athletic market, whenever temperatures drop or foul weather is expected, a three-layer clothing system has traditionally been viewed as the “go-to” clothing kit.

The kit is composed of a base layer to manage moisture; an insulating layer to protect you from the cold; and an outer layer that shields you from wind, rain and snow. You simply add or subtract layers as needed to adjust and regulate your body temperature depending on the working weather conditions encountered.

Determining what specific garments should be worn as layers is the critical step in building the ideal clothing system. The layers need to work well together to offer adequate warmth and breathability, while not being overly bulky and making it uncomfortable to move and work. Each layer should work well with the other layers based on where it lies in the system, offering stretch to enhance freedom of movement, breathability to prevent overheating, and good fit, which is a function of the fabric used and the design of the garment.

Great as ‘only layers’ and synergistic as a system

Protective clothing is not inexpensive and, as the old adage goes, you get what you pay for. One way to help manage the cost of your clothing systems is to select items that work well when used as standalone garments and work well – or even better – when used as part of a system during cold and foul weather. For example, a number of high-performance base layer shirting fabrics offer adequate arc flash protection (NFPA 70E) and low expected percentage body burn (NFPA 2112) to make them suitable for use as the only garment worn on the upper torso during hot weather.

Interestingly, when FR garments are worn together as a system, the level of the FR and arc flash protection of the system is often higher than merely adding the protection of each layer together. For example, a leading “8 cal” FR base layer shirt worn under a “12 cal” mid-layer garment might offer an ATPV rating in the mid-30 cal range vs. 20 cal (8+12). Thus, the synergistic “1+1 sometimes equals 3” effect can occur when layering FR garments.

The same can also be said in terms of the warmth of a clothing system. A person wearing three layers of light to mid-weight FR fabrics may feel warmer than an individual wearing a heavy FR bomber jacket over a base layer alone, even though those two layers weigh as much as or more than a performance three-layer system. This is because a proper three-layer system will manage moisture better, have a higher warmth factor as a system (Clo value similar to the R value for home insulation) and offer better freedom of movement than the two-layer system previously described.

Editor's note: This article represents the independent views of the author and should not be construed as a National Safety Council endorsement.