Let’s be honest.
Sleeping in a bivy sack is tough.
The good news is that bivy technology has come a long way in recent years.
One of the most useful advancements in most bivy sacks is the use of Gore-Tex on the exterior.
The Gore-Tex bivy has made the bivy sack more flexible, more resilient, and made it more possible for any lightweight or ultralight backpacker to get a decent night’s sleep even when the weather turns bad.
Best Bivy Sacks Ranked
How Military Bivy Bags Got Us To Gore-Tex
The original use of bivy sacks was strictly limited to the military and the few ultralight backpacking pioneers who braved the elements with minimal cargo.
These were simply just bags that went over the sleeping bag for extra warmth and weather protection.
Especially in the case of the military, these bivy’s were perfect since they cut down on the need for bigger, heavier shelters and soldiers could be out for longer periods of time.
Gone were the days that a unit needed to carry tents around everywhere they went and could get by with just a bivouac shelter.
Over time, however, the complaints of these old bivy sacks would pile up.
Complaints included inadequate rain and weather protection, stuffiness, excessive sweating, and overall lack of air circulation.
Fixing these problems would require a complete redesign of the bivy sack as we know it and Gore-Tex was a big part of that solution.
The official military bivy sacks now come with Gore-Tex and are one of the best selling bivy sacks amongst lightweight backpackers.
What Is Gore-Tex
Gore-tex is a fabric made by the Gore products company who design materials for both the private and public sector aimed at improving the quality of the products they’re built into.
The Gore-Tex in a bivy sack is a membrane bonded between a high-performance lining and outer textiles to create a tough, weatherproof laminate in the exterior of the bivy sack.
Specifically, it’s comprised of a thin layer of expanded polytetrafluoroethylene (ePTFE) which has over 9 billion pores per square inch.
When built into a bivy sack, Gore-Tex creates unparalleled waterproofing, wind-proofing, and air circulation.
In the case of rain, water cannot permeate this mean membrane and instead beads up on the exterior.
Wind is also denied entry into your bivy which many tents can’t even do.
Even textiles like microfibers, closely woven fabrics, and many fleece materials that claim to be windproof allow a little bit of wind to penetrate inside.
Technically speaking a fabric can only be considered truly windproof if its air permeability is 1.0 cfm (volume of air that passes through one square foot of fabric in one minute) or less and most of these other fabrics don’t comply.
On the other hand, all Gore-Tex products meet or exceed these standards.
While Gore-Tex’s weather protection keeps you dry and warm, it’s ability to circulate air is truly revolutionary.
The fabric’s breathability refers to how well it lets your sweat escape in the form of moisture vapor.
This feature is incredibly important to anyone sleeping in a bivy sack.
One of the biggest complaints about Bivy Sacks is how they build up condensation.
The tight space in a bivy sack creates more stale air and traps heat more easily.
This can turn your bivy sack into an oven and leave you feeling like a baked potato.
You’ll wake up drenched in your own sweat, even if it’s cold outside.
The Gore-Tex bivy membrane allows moisture to escape while keeping you warm and dry inside.
Which Gore-Tex Bivy Works Best
The beauty of buying a bivy sack in 2018 is the amount of variety.
There are different styles of bivy’s that range in quality from basic sleeping bag covers to mini 1-person tents.
You can get bivies with hoops that create space between your face and the bivy material.
Some have the ability to be staked which helps create some extra space inside.
Most are ultralight weight.
The heaviest bivy sacks are around 3 pounds.
Even bivy’s with hoops weigh between 2 and 3 pounds.
One of my personal favorite bivy sack features is meshed bug netting over the head.
This helps circulate air and keeps things cool inside the sack.
Not to mention if it’s a nice, clear night you can star gaze without worrying about bug bites.
In regards to Gore-tex keep in mind that not every bivy sack includes Gore-Tex.
There are other Gore-tex knockoffs that are usually made by the manufacturer of the bivy sack.
While they promise Gore-tex performance, some of them fall short.
For supreme weather protection and comfort always look for a bivy sack that includes Gore-tex specifically.
Gore-Tex Bivy Setups
The beauty of any Gore-Tex bivy sack is its portability and its ease of use.
There really isn’t any shelter that’s as easy to carry and set up as a bivy sack.
They roll up to the size of a small football and simply require being unrolled and unzipped.
Many bivies have the option to stake it down or run a rod through the fabric to create a dome.
Even these extra features take up little space in your pack and are easy enough for even beginners to use.
Plenty of backpackers use their bivy sacks as emergency backup shelters.
If their primary tent falters the bivy is there.
Especially since it takes up such little space it’s not hard to have one on hand just in case.
Disadvantages of Gore-Tex
As much good as Gore-Tex does, there are some drawbacks.
Maybe the biggest drawback is that it’s so good it encourages you to take unnecessary risks.
While your Gore-Tex bivy is waterproof, some campers might be tempted to set it up in wetter conditions.
It might encourage you to brave weather that you may not be fully prepared to deal with.
Campers also tend to overestimate the breathability of their Gore-Tex bivy.
In hotter conditions, you’re still going to get very warm inside and probably experience excessive condensation.
Even in cooler conditions, the Gore-Tex might not be as breathable as you like and you may still get some condensation.
The inclusion of Gore-Tex fabrics into the construction of bivy sacks was a huge upgrade.
Some would say this is what helped make bivy sacks more mainstream.
Making sure your bivy sack includes Gore-Tex is a must if you’re camping with a bivy.
You’ll have an ultralight shelter that can withstand rain, wind, and cold.
At the same time, you’ll get good air circulation to help you stay comfortable.
Although Gore-Tex isn’t perfect it certainly is an upgrade from the original bivy bags.
Also be sure to keep an eye out for Gore-Tex built into other outdoor items like tents and boots!