Winter Boot Basics: Insulations & Technologies

Know your shearling from your sheepskin? Prep for winter with this guide to winter boots and insulation.

The key to any good adventure might just be the right pair of winter boots.

Think about it. From a muddy backcountry hike to a day on the slopes, your winter boots keep you in step in harsh conditions—protected, warm and stable as you move. So when you’re prepping for your next outing, it’s important to know a thing or two about your outdoor footwear.


winter boot basics

The Upper: The soft, outermost portion of your boot is the upper. This component is typically made of materials like leather, suede, rubber or synthetics.

Lining: When it comes to warmth, it’s all in the lining.  Boot lining can be comprised of fleece, fur, sheepskin or synthetic materials. Many brands offer heat-seeking technologies, which use specialized fibers to trap and retain warmth. And don’t forget about waterproof liners.

Removable Lining: Removable boot lining lets you customize your level of warmth, trading a thermal liner for an all-weather one as the conditions change. If your boot is wet at the end of your trek, you can simply remove the liner to allow it to dry faster.

Midsole: Molded materials, like EVA or polyurethane, provide support and shock absorption for comfort. Keep in mind—the thicker the midsole material, the more warmth your shoe will provide, as your foot is farther from the ground.

Outsole: The all-important outsole is critical for trekking through snowy, muddy and rainy terrain. Traditionally, boots come with rubber outsoles, and for good reason: Rubber is naturally waterproof and slip-resistant.

When shopping for winter boots, always refer to the thickness of the outsole. Many boots come with spikes or lugs for walking over technical terrain. Many are designed to be slip-resistant and come with specialized tread patterns.

Toe Box: The toe box is a layer of protection that extends over your toes. Some toe boxes are covered with a layer of insulation for extra warmth. Work boots often come with steel or composite material toe boxes.


For maximum performance, always go for weather-specific materials and technologies. You can often find these materials in winter boots across popular brands:

  • Down is Mother Nature’s best insulator, providing a warmth-to-weight ratio that has never been replicated by any man-made product. Down is, however, highly susceptible to moisture, so avoid splashing through puddles.
  • GORE-TEX is a unique porous lining that repels and blocks moisture while maintaining breathability. It’s commonly found in boot liners that feature nylon and polyester. 
  • Fleece is lightweight yet thermal. It also wicks moisture to keep you dry and comfortable.
  • Shearling is a fine fleece that can be produced naturally or artificially. Like traditional fleece, it’s soft and cozy, but not well-suited for extreme conditions.
  • PrimaLoft is a synthetic insulation that’s water-resistant, quick-drying and thermal. Best of all, it’s extremely lightweight for warmth without extra bulk.
  • 3M Thinsulate uses small fibers to retain warmth while still allowing moisture to escape for breathability.
  • Sheepskin lining is naturally soft-textured and moisture-wicking for performance in extreme temperatures. Plus, it’s plush enough to provide an extra layer of cushion in your footwear.
  • Aerotherm is an innovative, eco-friendly insulation developed by NASA. Available exclusively at DICK’S Sporting Goods, this boot insulation is based on the unique properties of Aerogel and is 2 to 8 times more effective than traditional insulation. It protects against both extreme cold and hot conditions while maintaining a lightweight feel. Some boots actually feature Aerotherm insulation beneath the sole of the boot for superior warming power.

When you reach successfully the end of your outdoor excursion—your hike, your work day or your run down the mountain—it might be thanks to that just-right pair of boots.