What Does Waterproof Breathable Mean? 

"Waterproof Breathable"

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Is that Waterproof AND Breathable or is it Waterproof OR Breathable?

Gore-Tex, Neo Shell, eVent and other waterproof membranes are funny things. For many people it's the layer they reach for anytime the weather isn't perfect. The thing is that those waterproof breathable membranes just don't seem to breathe very well when it's wet out and as far as I can tell, nothing does. The problem is physics.

Okay, so I talked about membranes, what are those? There's two classes of waterproof jacket out there - membranes and coatings. Membranes work by bonding a membrane to an outer material (and often another layer or two) while coatings are just that - something basically slathered onto the outer material with maybe a protective layer or raised profile on the inside. Membranes - like Gore-Tex and eVent tend to breathe better, but the jackets also tend to be heavier, less packable and more expensive. Coatings - like Marmot's NanoPro or Pertex Shield+ are lighter, less expensive, but less breathable and often less durable that their membrane counterparts.

The Waterproof Breathable Problem

Waterproof breathable membranes and coatings work on the principle of diffusion. Diffusion needs a difference in humidity on each side of the membrane in order for your jacket to accomplish anything. The bigger the difference, the higher the rate of diffusion. When you are working hard, it's wet inside your jacket, so it's best at moving that sweat to outside your jacket when it's dry out. 

Pissing rain means it's pretty damn humid out - which means the driving pressure for diffusion is low or straight up zero which means maybe your jacket is waterproof, but it just isn't very breathable. If you are sweating while it's pouring raining, you're getting wet. If the humidity outside your jacket is the same as the humidity inside your jacket - then there's just nowhere for your sweat to go, so unless there's some crazy voodoo going on that I don't know about, I don't know how a breathable jacket could keep you dry while you are working hard in a humid environment. It's certainly what I've experienced during my time in the super wet coast mountains of BC. 

If you want more info on how waterproof breathable membranes and coatings work, REI has a really good article on it.

What it really comes down to, is if it's raining out, you have three realistic options: 

1. Say screw it to a shell, get wet from rain. Works when it's warm.
2. Wear a waterproof shell, work hard and get wet from sweat which is generally warmer than getting wet from the rain, but you freeze when you stop.
3. Wear a waterproof shell , realize that it's going to breathe like shit, even if you have the fanciest thing out there because the humidity inside and outside the jacket are so similar and restrict yourself to only going as fast as you can go without seriously sweating. If you start getting wet, slow down. 

Notice that there's no solution for 'stay dry while working hard in the rain'. There just isn't anything out there that can do that at this point.

The real reason to carry that waterproof-breathable jacket on a ski tour is for the way down - protection from snow while you're skiing - but do you really need to pay for the most breathable possible jacket to get that done?

The Alternative Solutions

I have a different way of doing things. In fact, I have two. The first is 'the two jacket system' and the second I call 'the honest compromise'.

I'm going to reference gear that's currently in the review-cue since I've got it lying around and have used it recently, but there's lots of options to everything.

The Two Jacket System

The two jacket system basically breaks the goal of your shells down into component parts - instead of using a jacket that is decent (at best) at everything, let's use one jacket that's super breathable and one that's waterproof.

This is the system I use in the summer for climbing, scrambling and general mountain fun.

The Breathable Jacket

There are some amazing wind shells out there. These things shrug off wind and even light rain thanks to DWR coatings. I've used the Patagonia Houdini and the Arcteryx Incendo recently and they're both featherweights that disappear into your pack and breath miles better than any waterproof breathable jacket out there that I've tried. They even handle short bouts of light rain without too much complaint. 

I'm currently reviewing the Outdoor Research Helium II. While breathable, it's not as breathable as a membrane jacket, but it IS just as waterproof. If it's currently raining, then how breathable something is really doesn't matter that much because nothing is getting past the simple fact that the humidity inside and outside my jacket is the same damn thing so just as much moisture is diffusing IN to my jacket as OUT.

Now, nothing says you can't bring a membrane jacket and if the humidity isn't 100% and it's only a light drizzle,  then yea, the membrane jacket is going to be more breathable, but the difference just isn't that big and some of the coating jackets are way lighter and pack way smaller. The extra size and weight for a membrane jacket may not be worth it.

The Two Jacket Bottom Line

By giving up on the idea of one jacket doing everything and going with two jackets - I have a breathable jacket when I need a breathable jacket and I have a waterproof jacket when I need a waterproof jacket. The real kicker is that the two jackets combined can be lighter and cheaper than a single membrane based waterproof breathable jacket.

The Arc'teryx Beta AR jacket is basically the standard against which all other waterproof breathable jackets are measured. It's light at 460g advertised weight and uses the latest Gore-Tex Pro membrane, but it's also expensive at an eye-watering $700CAD. You can save some money by going with the MEC Synergy jacket at 438g and $425CAD.

My current Two Jacket system uses the Patagonia Houdini as a wind layer that clocks in at a measly 102g advertised weight and despite being made by 'Pata-gucci' only costs $119CAD. For a waterproof layer, I'm currently trying the Outdoor Research Helium 2. As you'll see in the upcoming review, it happily keeps me dry, it's breathable enough that I don't need to immediately switch layers when the rain stops, comes in at a super light 180g advertised weight and only costs $220CAD.

The traditional waterproof breathable system clocks in at 460g and $700CAD on the high end and 438g and $425CAD on the low end. In comparison, the two jacket system is going to cost you in the neighbourhood of $340CAD and weighs 282g.

It's counter intuitive, but by going with two jackets, you ca save money, you can save weight and you can save space in your pack.

Even if you just can't wrap your head around the idea of leaving your trusty Gore-Tex jacket at home, being willing to leave it in your pack until it's genuinely raining and using a lightweight wind shell when it isn't is going to make you more comfortable for any reasonably high output activity.

The Honest Compromise System

The Honest Compromise System is designed for the needs of winter mountaineers. It's a system that I've wanted to see for ages and thanks to the dead bird people, it's starting to be a real thing.

A caveat: this system really only works in the winter. Once you're dealing with actual rain, it's time for the two jacket system.

When you're ski touring, you need something that's breathable on the way up and waterproof. The thing is, your shell doesn't need to be waterproof everywhere. Snow doesn't settle on vertical surfaces the way rain does - so what you really want is a jacket that has waterproof shoulders and arms, but is super breathable elsewhere. Likewise for pants, a waterproof butt and lower legs is really nice, but most other places, breathable is what you really need.

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This brings us to the honest compromise. I spent this ski season rocking the Arc'teryx Procline Comp jacket and I used the Lythic Comp pants for a couple of seasons. It strategically balances waterproof panels of Gore-Tex Pro where you need waterproof and a super breathable, and stretchy softshell where you don't.

The result is pretty awesome and I really like this as a solution for higher output winter activities. 

The Honest Compromise Bottom Line

With the honest compromise jackets you have a shell that breathes enough that in cooler weather at least, you don't need to strip off your shell on the way up and is waterproof where you need protection from snow. It's not suitable for rain, because that'll soak through the softshell panels, but in the winter it's pretty ideal. I've also used these compromise shells for ice climbing and they're pretty solid there too.

The rub, is that the jacket still isn't breathable enough for spring touring, you still need to use a wind layer if it isn't cold enough to keep your sweating at least a little bit in check. If it's a nice spring day with blazing sun and my main concern is wind, I'm still going with a wind shell, but for those mid-season days when it's puking snow and pretty crisp out, these are the one jacket solution.

They are an honest compromise - they trade 'waterproof' for breathable because you just don't need 100% waterproof most of the time in the winter and the result is better because of that honesty. I really hope other brands jump on this trend.

The Waterproof Breathable Reality

I worked in retail for years and in that time I could not count the number of people who brought in a brand new Gore-Tex jacket and told me it was defective because they got wet while wearing it in the rain. The jacket was waterproof - but because there wasn't enough of a difference in moisture on each side of the membrane, the diffusion required to keep that person dry from sweat just wasn't there. 

For low energy output activities like light hiking - you can get away with a single waterproof breathable jacket. For high energy output activities like ski touring, a waterproof breathable jacket just isn't going to breathe well enough for most people. If rain isn't actually a worry, then be honest about that and ditch the waterproof and go with breathable with strategic regions of waterproof. If rain IS a worry, then either go slow, or get wet.

How are Waterproof Ratings Determined?

Waterproof ratings are determined by the clothing manufacturer or fabric producer, with testing done either by independent laboratories or in-house. There are a number of different testing protocols in use, but most involve the equivalent of placing a 1” x 1” square tube over the fabric and determining how high (in millimeters) a column of water you can suspend over it before it starts to leak. Some manufacturers have developed their own testing methods that involve adding pressure to the process to simulate the effects of wind.

While waterproof ratings are becoming more standardized, remember that different labs may test or report differently, and may come up with different results even with two pieces of fabric from the exact same roll, so take the numbers with a grain of salt. Keep in mind that some manufacturers report waterproof ratings in PSI (Pounds per Square Inch) rather than millimeters, which has a conversion rate of 704 mm = 1 PSI.

How are Breathability Ratings Determined?

Like waterproof ratings, breathability ratings are determined by both manufacturers and independent labs, but the testing methodologies are quite diverse and almost impossible to compare with each other.

Results can vary wildly based on test, temperature, humidity and pressure and are not standardized from brand to brand, or test to test. Most testing doesn’t reflect real world winter conditions, like near freezing outside temperatures with high relative humidity. Since manufacturers seldom reveal the actual test used, and are probably keen on reporting the highest possible figures to promote sales, it’s best to read these numbers with the eye of a skeptic, but generally within a given brand or family of fabrics it’s safe to say more grams is more breathable (if a company grades breathability on an RET scale – Resistance to Evaporative Heat Transfer – a lower value is better).

How Breathable a Garment do I Need?

You can get away with a low breathability garment if you aren’t going to work up much body heat or maybe you won’t be out and about for too long. Higher breathability helps for active uses like running, and the ski touring & splitboard crowd to avoid quick wetout inside their layers caused by their own physical exertion. So, you'll want to look out for breathability in your ski jacket, but it might not be important if you're just wearing it around town.

If you're looking for a snowboard jacket, your riding is lift-served, you don’t hike to out-of-the-way lines, and you take regular breaks in the lodge where you remove your coat, a breathability rating of 5,000 to 8,000 grams will probably be fine. This goes for more casual uses, too.

If you do a lot of “high energy” riding, hiking, or running where you often break a sweat, look for breathability in the 10,000 to 15,000 gram range. Backcountry skiers & snowboarders, runners, and mountain bikers should look for garments with breathability in the 20,000 plus range for the best results.

There are times when a layer of warm, moist air between your body and your shell can mean warmth as long as your underlayers don’t become saturated with moisture. In cold and dry weather, a super breathable shell can actually lead to visible clouds of water vapor exiting the wearer’s body, which leads to heat loss. It’s not uncommon for owners of eVent™ jackets, for instance, to need more insulation under their shells to stay warm.

How Waterproof a Garment do I Need?

Jackets and clothing with lower waterproof ratings are better suited for fair weather, low-moisture activities. Clothing and gear with higher waterproof ratings are ideal for people who need gear that will perform when the weather turns sour. People who wear backpacks often may also want to consider outerwear with higher waterproof ratings as the straps put pressure on the jacket and may force moisture through gear that has a lower waterproof rating. An intense, high-exertion day of activity in wet conditions with the added pressure of wind, sitting, and falling can put even the best-rated waterproof fabrics to the test.

We recommend a minimum waterproof rating of 5,000 mm, or 5k, for ski and snowboard jackets and snow pants. If you ride primarily in cold and clear conditions and take regular lodge breaks, this level of protection could be fine, but anything less and you stand a good chance of getting wet and cold in a storm. Clothing rated between 5,000 mm and 10,000 mm (10k) is a good choice for riders who spend long days out and ski or snowboard in any weather conditions. Avid skiers and snowboarders, especially those in wetter climates, should look for waterproof ratings in the 10,000 mm to 20,000 mm range or better. If you spend a good percentage of your time in the backcountry or hiking or skinning to remote locations, breathability becomes equally as important as waterproofing – look for outerwear with both waterproofing and breathability in the 20,000 plus range. As you might expect, higher ratings in both categories will usually mean higher prices. It is money well spent.

How Do They Make Fabric Waterproof & Breathable?

Waterproof breathable fabrics consist of an outer layer called the “face fabric”, usually made of nylon or polyester, and a laminated membrane or coating, usually made of ePTFE (expanded Polytetrafluoroethylene, also known as Teflon®) or PU (Polyurethane). The purpose of the face fabric is to protect and look stylish; it’s not waterproof but is treated with a solution called DWR (Durable Water Repellent) so it doesn’t soak up water. Sometimes a layer of insulation is added for warmth.

The job of keeping the water out is left to the membrane, which has tiny holes too small to let liquid water enter but large enough to allow water vapor to escape. Since contamination with oil, sweat and chemicals can cause PTFE membranes to lose their ability to keep out water, the membrane is protected by an ultra-thin layer of Polyurethane (GORE-TEX membranes have a bi-component laminate structure) or other oleophobic (oil-hating) treatment (eVent™ does this at the microscopic level with individual PTFE fibers). Finally, a fine scrim or mesh is bonded to the inner surface for comfort in 3 Layer (3L) fabrics. 2 Layer (2L) fabrics receive a separate fabric liner, while 2.5 Layer fabrics use an abbreviated pattern screened on the inner surface to save weight. Modern waterproof breathable fabrics have come a long way since the original GORE-TEX, and most are extremely waterproof at any price point, but outstanding gains in breathability in the past few years have redefined the market in high exertion outerwear.

To learn more about outerwear including fabrics and features, check out our Outerwear Construction Guide.

Membrane or Coating?

Waterproof breathable fabrics with ePTFE membranes, led by GORE-TEX, have dominated the market for years and still tend to offer the best combination of waterproof breathability at the high end of the market. As technology allows the creation of thinner and thinner layers, high performance Polyurethane and Polyester membranes are beginning to take up a larger portion of the market. Examples are Marmot's MemBrain® (Polyurethane) and SympaTex (Polyester). Membranes come in many different types and price ranges, but chances are you'll want a 2 Layer or 3 Layer fabric with a laminated membrane if you're looking for a versatile and durable snow garment. 3 layer fabrics (3L) have all the layers including the lining bonded together, while 2 layer fabrics use a separate fabric lining which makes for a bulkier garment overall. 2.5 layer fabrics have a raised pattern screened on the inside to keep it off your skin and are usually reserved for superlight rain garments.

Coated fabrics tend to be very waterproof but lack breathability in comparison to membrane laminates. These fabrics are less expensive and are improving as manufacturers finds ways to make the coatings thinner and more porous. Coated fabrics are great for emergency weather protection or for activities that don't involve a high level of exertion.

What is Durable Water Repellent or DWR?

DWR stands for Durable Water Repellent. It is the DWR treatment that keeps the outer layer of your fabric from getting soaked by precipitation. Almost all outerwear exterior fabrics are treated with some sort of DWR. The treatment is meant to keep the fabric from becoming saturated with water which can make the fabric feel heavier, colder, and impacts its performance.

DWR causes water to bead-up and roll off the fabric and is affected by abrasion, dirt and body oils. Falls on the mountain, rubbing against your pack or the chairlift, and normal use can cause the factory DWR treatment to wear off. This is why, after some use, a garment will appear to no longer be waterproof. 

It likely means the fabric needs to be refreshed by smiply washing the garment, re-applying the DWR treatment, or both. Aftermarket DWR treatmens in roll-ons, sprays, and wash-ins are available from companies like Nikwax to re-condition your waterproof/breathable garment after washing. Try a fresh DWR coat if you notice water soaking into the face fabric of your Waterproof/Breathable garments and you have already attempted to refresh the DWR by cleaning your outerwear.

DWR sprays are best applied to a damp garment after washing and thoroughly rinsing it (do a second rinse cycle without soap before you apply the DWR to make sure no detergent residue remains) and should be heat activated using a medium dryer or iron before use. Read the directions on both your garment and the DWR bottle before you start. We recommend spray DWR products rather than wash-in products, which deposit DWR on the interior of the garment as well as the face fabric and may interfere with the functionality of the membrane.

Note: Laws and regulations governing the use of DWR solutions continue to evolve, spurred by efforts on the part of the European Union and states like California to reduce the amount of PFAS (Perfluoroalkyl) chemicals being released into the environment. Originally, most DWR solutions were very effective "long chain" C8-based (8 carbon atoms in the molecule), but these have been largely banned worldwide due to the toxic "forever chemicals" they leave behind. C8's were replaced by C6 DWR formulas, but these too leave non-degradeable toxic compounds in their wake and are now being phased out in many parts of the world. 

What is GORE-TEX

GORE-TEX fabrics are created by laminating a GORE-TEX membrane to high performance nylon and polyester face fabrics. They come in several different grades, including GORE-TEX Pro, GORE-TEX Active, as well as just regular GORE-TEX and GORE-TEX INFINIUM™. GORE also offers soft shell fabric and a super light 2.5L fabric called Paclite. GORE-TEX garments are fully seam sealed and feature a “GUARANTEED TO KEEP YOU DRY®” promise.

Although many laminates are waterproof, a GORE-TEX membrane is capable of maintaining an extremely high level of waterproofness while staying very breathable thanks to billions of microscopic pores that let water vapor out and prevent liquid water from entering. W.L. Gore works hard to develop and refine waterproof breathable technology.
 

Electron microscope photography of GORE-TEX membrane

Introduced in , GORE-TEX Pro fabrics utilize a new membrane with no Polyurethane protective layer and significantly improved breathability. In , GORE introduced a new backer technology for 3 layer GORE-TEX fabrics called C-KNIT™ which uses a very fine nylon backer with a circular weave. C-KNIT™ fabrics also have improved breathability, a softer hand, and slide over mid layers more easily. GORE has also launched the GORE-TEX INFINIUM™ line of products for when comfort and performance matter more to you than total waterproofness.

In late , W.L. Gore introduced a new membrane technology based on ePE (Expanded Polyethylene) rather than their traditional ePTFE. Designed for long-term sustainability, the ePE membrane uses no perfluorochemicals (PFC’s) in its production and features performance very similar to other GORE-TEX fabrics, with exceptional waterproof performance and durability. Because of the ePE membrane’s strength, fabrics are expected to last longer and can be made thinner and more packable. Expect ePE GORE-TEX fabrics to gradually replace ePTFE fabrics beginning in -.

While some people refer to all waterproof/breathable fabrics as “GORE-TEX,” it’s a proprietary product and technology of the W. L. Gore Corporation. For more information on the GORE-TEX family of products, check out our GORE-TEX Guide.

If you want to learn more, please visit our website Waterproof Breathable Membrane.