Men’s Thermal Underwear – The Base Layer in Cold Weather Dressing

Mens-Thermal-Underwear-The-Base-Layer-in-Cold-Weather-DressingFall is here – and winter is right around the corner.  As such – it’s time to start thinking about layering.

Layering is the best way to protect yourself from extreme cold weather.  When done right, it can be the difference between smiling in a snow storm or realizing your weekend has been cut short because you’re not prepared.

unknown man with ice beard

Layering can be divided into three parts – The base layer, the insulation layer, and the protective outer layer.

This article covers the base layer, the layer many men either neglect or mistakenly wear the wrong type of fabric at.  Later this year we’ll cover the other two layers.

Please note – to supplement this topic I interviewed Thermal Underwear Expert Carol Davis of Carol Davis Sportwear.  You can download and or listen to the podcast using the player above.


Three Common Thermal Underwear Fabrics – Advantages and Limitations

Synthetic Thermal Underwear Fabrics – When it comes to a base layer in cold weather, synthetic fabrics made especially for these conditions are the gold standard. Often unique and patented combinations of polyester, nylon, spandex, and lycra, these high-tech man made fabrics achieve the ideal balance of moisture wicking and heat retention that no other fabric can match. Malden Mills in Malden, Massachusetts is a leader in the industry and their line of polartec fabrics are the best in the world for cold weather base layering.

Wool Thermal Underwear Fabrics – A close second, this fiber was developed by nature to work as a moisture wicker and heat retainer. Harder to find and somewhat expensive, it has been used for centuries by cold weather explorers, military, and hunters. The problems with wool however are that many people react negatively to it when it is placed close to the skin. Rashes, itching, and irritation can result.

Cotton Thermal Underwear Fabrics – A distant third, cotton is cheap and plentiful. However it insulates poorly and when worn as a base layer in cold weather retains moisture. This is BAD, as if cool air hits your skin – or enough moisture builds up, this can lead to rapid heat loss. Cotton is only useful as a base layer when you are going to be outside but relatively inactive (example – watching a sporting event or standing outside for less than a few hours). In this case it can hold in a warm air cushion – but not much else.


Why is Moisture Wicking So Important When Selecting Thermal Underwear?

The purpose of wearing thermal underwear is to stay warm.  To stay warm, you have to stay dry.

clothing water wick fabric


Your body, when it heats up, will try to regulate its temperature by perspiring. Under normal conditions this is great – the act of evaporation with pull heat from the skin surface, thus cooling it. When you’re covered in clothing however, this becomes a problem if the fabric isn’t designed to deal with the moisture.

Too much moisture build-up can result in a wet core, which if exposed to cool air will bring a rush of heat loss and/or saturate the core clothing which then loses its insulation properties. Which again can lead to rapid heat loss.

You want thermal underwear which effectively moves moisture through the fabric and out to the middle layer (what happens here is another article) Synthetics fabrics like Polartec and many wools do this – cotton does not do a good job when layered (worn by itself is another story).

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How Does a Thin Layer of Synthetic or Wool Fabric Keep Me Warm?

The secret is Loft.

polartec loft

Loft is the result of a low density weaves that ensures the fabric maintains its form and traps air.  Fabrics with good loft do an excellent job insulating you from heat loss and prevent the cold from seeping in.  They keep your body heated with minimal space and maximum flexibility – an important attribute for those wanting to minimize bulk.


Thermal Underwear Types – Advantages and Disadvantages


Extreme Cold Weather Thermal Underwear

mens carol davis sportswear


  • Will Wick Away Most Moisture
  • Great Fit – Built for athletic builds with higher armholes and lower trouser rise. Close fit along torso and connections to extremities – better movement allowed.
  • One Piece Build – Protects the midsection and you only have to buy one piece.
  • Extremity protection – wrists and ankle protection.
  • Provides medium to extreme protection against cold – adequate for exposure to cold and extreme cold with other layers (-40 to 50 degrees Fahrenheit – with other layers).
  • Multi-direction stretch fabric can be worn for long-term periods (24 hour plus) without fatigue.
  • Bacteria resistant – can be worn for weeks (hunters, campers, military)
  • Can be used in a wide variety of extreme conditions – SCUBA, Ice Fishing, Mountaineering, Hunting in Alaska, Living in Minneapolis during the Winter.


  • High Cost ($100-$300)
  • One-piece design not always optimal for those who only want top or bottom protection.
  • Not suited for cool weather protection (above 50 Degrees Fahrenheit) and will need to be taken off if temperature rises.
  • Made from thicker fabric that may fit close but still will add some bulk. May catch on clothing – although higher end builds often have a slick surface finish.

Company I Recommend Carol Davis Sportswear (Made in the USA)

I have purchased approximately 8 sets of Carol Davis’ thermal underwear over the last decade (FYI – they are called body socks on the website). Most I gave away as gifts, and the two I still have personally are in great working shape after 100 washes and even more wears. I have used them for cold weather motorcycle riding, cold weather running, on 2 Marine Corps deployments, and most recently they are daily wear from December to early March when I leave the house (I live in the Northwoods of Wisconsin). I have even worn them under my suits when I spent a lot of time moving through the frigid streets of Kyiv, Ukraine in the winter.

To learn more about this great American small business – listen to the audio above or visit my review of her cold weather thermal products here.


Performance Thermal Underwear

mens armour thermal underwear


  • Will Wick Away Most Moisture
  • Great Fit – Built for athletic builds with higher armholes and lower trouser rise. Close fit along torso and connections to extremities – better movement allowed.
  • Made from slick fabrics that do not catch and are made to be worn under other clothing or gear.
  • Provides medium to light protection against cold – adequate for medium exposure to cold (32 to 50 degrees Fahrenheit) weather.
  • Fun colors and designs


  • High Cost – $30 – $100 per piece (top or bottom)
  • Not suited for extreme cold protection (below 10 Degrees Fahrenheit).
  • Tight Fit may not work for long-term (24 hour plus) wear.
  • Two piece design does not always protect mid-section, wrists, ankles.

Companies I RecommendIcebreaker, Under Armour Cold Gear

My experience with these companies is limited. I have felt and looked at their clothing, and based off my research the fibers they use are quality blends or wool.  This is the basis of my recommendation.

A cost savings tip is to look for knockoff brands in your larger department stores – if you understand the fabric makeup, you can find similar performance gear for 1/3 the price. That’s the power of knowledge!


Inexpensive Synthetic Cotton Blend Thermal Underwear


mens thermal underwear


  • Lower Cost
  • Will Wick Some Moisture
  • Provides light protection – adequate for short exposure to cold (32 to 50 degrees Fahrenheit) weather.


  • Not suited for long term cold protection.
  • Provides little protection in extreme cold weather (10 Degrees Fahrenheit and lower)
  • Poor fit can create hot spots, discomfort and irritation

Companies I Recommend – Duofold Men’s Midweight Thermals

A good performer – I used to use these when climbing radio communication towers in Iowa during the winter. Not for extreme cold, these will do the trick for casual users.


Cotton Thermal Underwear 


  • Low Cost
  • Provides light protection when you are not active – adequate for short exposure to cool weather (40 to 50 degrees Fahrenheit).


  • Not suited for long term cold protection.
  • Provides little to no protection in cold weather (32 to 10 Degrees Fahrenheit) and can retain moisture thus leading to rapid cooling of the skin if large amounts of perspiration build up in the base layer.
  • Poor Fit – creates hot spots, discomfort and irritation

Companies I Recommend -None