A Simple Outdoor Clothing System Layer 6: Waterproof/Breathable Shells

Rain Gear
When it rains, you need rain gear. Lake One, BWCAW.

Rain, rain, rain, rain, rain, rain, rain–it happens. When it does, quality waterproof/breathable rain gear can save the day.

This is the seventh in a series of articles outlining a simple clothing system for outdoor recreation. An overview of the system is offered here. Topics covered include baselayers, lightweight fleece insulation, midweight insulating jackets,  wind shells, and winter soft shells.

This article is a bit of a whopper and meanders in and out of all kinds of techno-geek gobbleygook. If you want to cut to the chase, you can skip to the bottom and read the “Buy This, Not This” section. If you’re looking to nerd-out on raingear, carry on.

Traditional Rainwear
In the summer of 2004 I did an internship at the Voyageur Outward Bound School in Ely, MN. As part of our training we went on an 10-day trip through the Boundary Waters using the gear that students would be issued for their Outward Bound courses.

We slept in Eureka Timberline 4 tents on Ridgerest pads, paddled 17 and 18 foot Grumman aluminum canoes, and tried to keep dry in Helly Hansen PVC rainwear. Nicknamed “smelly Hellies” these suits consisted of bib-waisted rain pants and a hooded jacket. They were coated in a rubberized PVC waterproof membrane that was extremely tough and perfectly waterproof. This is the kind of gear you see on Deadliest Catch. It was tough enough to be issued to student after student without developing leaks and it kept out the heaviest rain.

The smelly Hellies also kept IN any perspiration that your body might produce while portaging 70 pound canoes and food packs. Hence the name. The PVC fabric did not breathe in any way, and once you started to exert yourself you had to choose between being soaked from sweat, or soaked from rain. Once your clothes were soaked with sweat there was little you could do to dry them off until you got to camp and could hang out under a tarp.

Waterproof/Breathable Rain Gear
For many years the only option in rain gear was non-breathable fabrics like the commercial fishing gear we were issued at Outward Bound. In the late 1970s and early ’80s fabrics began to show up that offered the promise of waterproofness combined with breathability. Best known of these is Gore-Tex, which uses an expanded PTFE (polytetrafluoroethylene) laminated to a face fabric and backed with a variety of inner scrims or liners.

The Gore-Tex membrane is microporous, which means that it is permeated by billions of microscopic holes. These holes are smaller than a drop of water, but larger than a molecule of water vapor. This allows water vapor to pass through the membrane while preventing liquid water from doing the same. Gore-Tex is both waterproof and breathable and was a breakthrough in rainwear technology.

The earliest Gore-Tex garments had a few problems. The outside seams needed to be sealed by hand with the same kind of seam sealer you would use on a tent floor. This made for a pretty unfashionable raincoat. Worse still was the tendency of Gore-Tex to deteriorate when exposed to body oils–prolonged exposure to sweat and grime would cause the membrane to leak.

Both these challenges were solved by the end of the 1980s. Seam tape was developed that allowed seams to be internally and permanently sealed with heat. This fixed the seam problem and allowed jackets to reach a broader audience. The body oil problem was solved by adding an oleophobic (oil repelling) coating to the inside of the PTFE laminate. This effectively eliminated the tendency of the waterproof membrane to deteriorate with use. After these refinements, Gore-Tex fabrics became increasingly popular and eventually came to dominate the technical rainwear category.

Gore-Tex waterproof/breathable jackets. Left: lightweight rainwear. Gore-Tex Paclite 2.5-Layer fabric. Right: mountaineering hard shell. Gore-Tex Pro 3-Layer fabric.

Fabric Construction Types
Second generation Gore-Tex garments were constructed of an outer fabric that was bonded to the waterproof PTFE membrane. The membrane was seam taped on the inside and protected from abrasion by a hung liner of nylon taffeta or mesh. This type of construction is referred to as 2-Layer Gore-Tex, because the waterproof/breathable membrane is bonded to the face fabric alone. Face fabric plus membrane equals two layers. A later development was a version of the fabric that sandwiched the waterproof membrane between an outer face fabric and an inner scrim fabric. This construction has three layers (face fabric, membrane and scrim) and is referred to as 3-Layer construction.

A more recent development are the so-called 2.5-Layer fabrics. These feature an outer face fabric laminated to the Gore-Tex membrane but do not have a hung liner or an inner scrim layer. The surface of the membrane itself is in contact with your skin or inner clothing layers. This surface is treated with an additional coating to improve durability. Gore Paclite is a 2.5-Layer fabric.

In the early days, 2-Layer fabrics were favored because they draped well and had a softer hand, while 3-Layer fabrics were used when additional durability was needed. Some manufacturers combined 2-Layer and 3-Layer fabrics in the same garment, using the lighter fabric for the body of the shell and the more durable fabric in high wear areas like elbows, seat and knees. These days, 2-Layer construction is used in less expensive garments, 3-Layer is used in durable clothing for hard use in the mountains, and 2.5-Layer is used in lightweight rainwear. Lightweight rainwear is what we are looking for in Layer 6 of our simple clothing system. This is where we’ll focus our attention.

Big fishing action. Insula Lake, BWCAW. Waterproof/breathable fabrics perform best in sedentary or low intensity activities. Top: Mountain Hardwear Gore-Tex Paclite jacket. Bottom Mountain Hardwear Epic pants with proprietary coating.

Other Waterproof/Breathable Fabrics
Gore-Tex may have been the earliest and most commercially successful waterproof/breathable fabric, but it is not alone in the marketplace. A wide array  of proprietary waterproof/breathable fabrics are on the market today. Most are made from polyurethane rather than PTFE. Some are microporous, like Gore-Tex. Others are monolithic (unpermeated) and move moisture outward through the waterproof membrane by absorbtion and diffusion. The technicalities can be bewildering and you can easily blow an afternoon on the web if you head down the rabbit hole chasing the details of waterproof/breathable technology. We’re not going to do that here.

Alternative waterproof/breathable fabrics are available in a the same three basic configurations as Gore-Tex: 2-Layer, 2.5-Layer and 3-Layer. They are typically placed at price points below Gore-Tex products, and are frequently less breathable and less durable than their Gore-Tex counterparts.

One exception appears to be eVent, which is a PTFE laminate similar to Gore-Tex. My understanding is that the eVent folks found a different solution to the body oil issue than an oleophobic coating. The absence of this coating helps eVent to breathe exceptionally well. Durability is uncertain but looks promising. I have an eVent drysuit that is holding up well after several seasons of use. My wife has an REI eVent rain coat that has seen a couple years of use and is still keeping her dry. So far, so good.

The most popular among the alternative waterproof/breathable fabrics are the 2.5-Layer fabrics found in affordable, lightweight rainwear. Marmot more-or-less invented this category more than a decade ago with the $100 Precip Jacket–a full-featured raincoat with a waterproof/breathable polyurethane coating. Patagonia sells a similar garment called the Torrentshell Jacket. Nearly every major manufacturer of outdoor clothing has a similar offering at a similar price. The vast majority of them are very good, and performance continues to improve as new coatings are developed. Over the past decade I’ve used the Marmot Precip, Mountain Hardwear Epic and Patagonia Torentshell Jackets. All provided waterproof performance and decent breathability at an affordable price point.

Waterproof/breathable fabrics. Left: REI brand rain shell. EVent 3-Layer construction. Right: Patagonia Torrentshell Jacket. 2.5-Layer H2No waterproof/breathable fabric.

How Waterproof/Breathable Fabrics Function in the Real World
I’ve already touched on the general idea behind waterproof/breathable fabrics like Gore-Tex–liquid water can’t get through, water vapor can. Simple.

Not so fast. That’s the theory. In practice there is a lot to know about how these fabrics actually perform in real world conditions. One of the biggest misunderstandings has to do with face fabrics and DWR.

Regardless of whether they are 2-Layer, 2.5-Layer or 3-layer, the vast majority of Waterproof/breathable garments feature a face fabric on the outside with a waterproof membrane on the inside. The face fabric is not waterproof. The membrane on the inside is. This means that the face fabric can soak up water. To prevent this, face fabrics are treated with a water repellent that helps water to bead up and run off. These treatments are called durable water repellents (DWR).

DWR treatments will repel water for a while before they are overcome by moisture. Once the DWR is defeated, the outer face fabric of the garment will begin to soak up water. This is called “wetting-out”. Once wetted-out, the garment will still be waterproof, but it may feel like it is leaking. A soaked face fabric will be cold and if you are sweating inside the shell you will feel wet. The sensation of perspiration trapped within a waterproof/breathable shell and a wetted-out face fabric feels wet and cold and you would swear the thing is leaking. It isn’t, but it sure feels like it is.

[If you want to try an experiment that demonstrates the “leaky raincoat” sensation, try this: put on a pair of latex or nitrile gloves and run your hands under the faucet. Use cold or cool water. It’s remarkable how wet your hands will feel even though you know the water isn’t touching your skin. Try this for a minute or so and then pull off the gloves. Your hands will be dry underneath. The gloves didn’t leak, but they sure felt like they did.]

Why would sweat be trapped inside a breathable jacket? The reason is that these fabrics are breathable in optimum conditions, but not in all conditions. In order for water vapor to pass through the waterproof/breathable membrane, it must remain in vapor form. If you are sitting still, you skin is constantly passing a tiny amount of water vapor out into the environment. As you begin to exercise you first produce more vapor and later liquid sweat forms on your skin to help cool your body. This liquid can’t pass through the waterproof/breathable membrane from the inside anymore than rain can get in from the outside. It’s going to be trapped inside your clothing system.

So sweat is one problem. If you are all sweated up, you’ll have to use body heat to turn that water to vapor before it can pass through the waterproof/breathable membrane to the outer environment. But sweat isn’t the only challenge that waterproof/breathable fabrics have. A big part of how well a waterproof/breathable functions has to do with the difference between the micro-climate and the macro-climate.

The micro-climate is the area contained within your outer shell. The macro-climate is the environment outside the shell. Waterproof/breathable membranes rely on a temperature and humidity gradient to drive water vapor out through the garment. If temperature and humidity are high inside the jacket (micro-climate) and low and dry on the outside (macro-climate), there is a strong pressure gradient and breathability is optimized.

On the other hand, if the micro-climate is warm and humid and the same conditions exist in the macro-climate (think summer rainstorm) there is little driving force to push vapor through the shell layer. Breathability will be reduced. If you start exerting yourself you’re likely to be wet from sweat even if you are protected from rain.

Worse still, once your DWR wets out, your rain gear won’t breathe nearly as well. The layer of saturated fabric on the outside of the waterproof membrane increases the outer humidity level to 100 percent. This dramatically reduces the breathability of the garment, so wetting-out not only makes your jacket feel as if it is leaking, it also traps more sweat inside the garment so you feel wetter than you would have if the DWR was still functioning.

What all this means is that, in the worst conditions, breathable fabrics don’t really breathe very well. I recall talking to Nigel Dennis at one point about “breathable waterproofs” for sea kayaking and he insisted that the fabrics’ greatest virtue was that they would let your under layers dry out once you stopped paddling. This seems right to me. If it is pouring down rain and you’re exerting yourself in a breathable waterproof jacket you’re likely to be soaked with sweat. Once your activity level drops, your body heat will begin to convert your sweat to water vapor and drive it out of your insulating layers. If you are wearing a good, lightweight baselayer, your body heat will drive moisture away from your skin and you’ll begin to feel dry again. The ability to dry your insulating layers while wearing a waterproof shell is perhaps the most important advantage that breathable waterproof membranes have over traditional, non-breathable fabrics.

How Breathable?
Oh boy, here’s a can of worms. There are all sorts of tests out there that rate the breathability of semi-permeable membranes. The question of which ones breathe the best is hotly contested. On the bench, in the lab, in ideal conditions, there is definitely a difference between different products. In challenging real world conditions it can be harder to tell.

I’ve used a range of fabrics including Gore-Tex, eVent and proprietary coated fabrics like MemBrain, Epic, and H2No. My assessment is that, once you past the $100 price point for a jacket, most of the fabrics breathe pretty well when the shell is dry and you aren’t sweating up a storm.

They all also breathe like a plastic bag once the face fabric is wetted-out and you are working hard. Especially in warm, humid conditions. Every single waterproof/breathable technology I’ve tried has been overpowered by sweat at some point in the field.

This is the reason that the US Army transitioned away from Gore-Tex shells in its cold weather clothing system and toward air permeable soft shells. It’s the reason that, within the framework of my proposed simple clothing system, I suggest that you use waterproof breathable shells only as a last resort when it’s raining hard. Stick to your wind shell or soft shell layers unless it is truly pouring. You’ll be more comfortable if you do.

To reiterate: there IS an objective, measurable difference in breathability between different products, and you can dig into the details if you are interested. In my experience, in the sweaty, rainy, subjective world, no waterproof breathable fabric will breathe as well as you would like. Probably the single most important thing that you can do to improve breathability in any jacket is to maintain the DWR.

DWR Treatments
The fact that the water repellent treatment on the face fabric of waterproof/breathable garments has so much to do with breathability means that it’s important to keep your DWR as fresh as possible. When your DWR breaks down, your garments stop breathing and feel like they are leaking. This is something we want to prevent.

There are two ways to restore the DWR on waterproof/breathable fabrics. The first is to wash the garment with a specialty soap and tumble dry. Do not use a standard laundry detergent. Conventional detergents include chemicals that adhere to fabrics in order to improve wash performance. These surfactant agents will WRECK the DWR on your waterproof/breathable garments. Never use them. Instead of your regular detergent you need to use a special soap like Nikwax Tech Wash. Wash your garment with a non-detergent soap and then tumble dry on low. Washing removes grime that hinders the DWR. Tumble drying helps to renew the treatment and restore water repellency.

If the wash and dry technique doesn’t do the trick you can use a wash-in or spray-on treatment to restore water repellency. Nikwax TX Direct is a good option. TX Direct Wash-In is the product you should use for the lightweight 2.5-Layer rain shells recommended in this post.

How Waterproof?
Breathability is complex. Waterproofness is simple. If you buy a seam-taped, waterproof/breathable garment from a well-respected outdoor brand, it will be waterproof. Gore-Tex fabrics are waterproof. EVent is waterproof. All the proprietary waterproof/breathable coatings used by reputable manufacturers are waterproof. In the world of outdoor clothing, waterproofness doesn’t seem to be the biggest problem. Breathability and durability offer greater challenges.

My Precip jacket was waterproof and breathable, but it wasn’t very durable. The coating began to peel away near the seam tape in the upper shoulder and hood area after a few years of use. I had a similar experience with the Mountain Hardwear Epic Jacket that I bought to replace the Precip. Mountain Hardwear offered to credit me toward another jacket under warranty and I chose to replace the Epic Jacket with a slightly heavier version in Gore-Tex Paclite. This raincoat has now seen a decade of use and is still waterproof and going strong. Based on these experiences I give the nod to Gore-Tex Paclite in the durability department.

When it comes to rainwear, I think it makes sense to purchase garments from a company that is known for warranty, especially if your budget restricts you to some of the less expensive, less durable options.

With respect to warranty, Gore-Tex products have a bit of an edge. The company has a warranty against delamination of their fabrics. This means that manufacturers are backed up by Gore and can offer more comprehensive replacement programs for Gore products than they might for less expensive coatings. Over the past 20 years I’ve had two Gore-Tex jackets that began to delaminate in small areas. Both of them were replaced by the manufacturer under warranty.

Of course, warranties don’t cover use and abuse, so don’t think you can send in your jacket if you burn a hole through it, wear through the fabric on sharp rocks or otherwise use the thing up. If the DWR wears off you need to restore it yourself. That’s not warranty. Warranty is when the waterproof fabric begins to delaminate or peel off early a garment’s life. This doesn’t happen all that often, but it can happen, and it’s nice to have the option to send the garment in for evaluation.

I’m dwelling on warranty here a little bit for a couple reasons. First, you’ll be spending a fair amount of money on waterproof gear, and waterproof gear, unlike a windbreaker, can fail. I’m not saying your raincoat WILL fail. It probably wont. But it’s reassuring to have an option to replace failed gear under warranty at a nominal cost if something goes wrong. Second, I’m convinced that most folks out there don’t take the time to bother with warranty service if they have a piece of gear that fails. This is a mistake. If you take the time to contact a manufacturer and mail in your garment they’re almost always happy and willing to help. If the product actually is defective you will likely receive a replacement or a partial credit toward a replacement.

Choosing Rainwear
Understanding how rainwear fits into the simple clothing system will go a long way toward helping you decide what kind of clothing to buy. In this system, rainwear is only to be used when it is actively raining, and ideally when you are sedentary. This means you’ll be carrying your rainwear more often than you’ll be wearing it on backcountry trips. Wind layers or soft shell layers will get more use and abuse than raingear in most cases. With these factors in mind it makes sense to choose the lightest rainwear that you can get away with. Choosing the right kind of fabric is key to getting the balance between durability and weight right.

Which Fabric?
The 2.5-Layer fabrics like Gore-Tex Paclite, Marmot Precip, Patagonia H2NO and similar are the right choice for lightweight rainwear. Garments made from these fabrics are lightweight, breathable and pack down small.

The only reason to choose heavier fabrics would be if your backcountry travels will take you through extremely brushy or rugged terrain that would shred a lightweight face fabric. If you are backcountry hunting or bushwacking through rough terrain you may want to opt for raingear constructed with a heavier face fabric, and perhaps one of the 3-Layer fabrics that offer better overall durability.

ECWCS Gen III Level 6 top and bottom. Gore-Tex Paclite.

The US Army has, for several years, been fielding a rain suit made of Gore-Tex Paclite laminated to a burly outer face fabric as part of its Extended Cold Weather Clothing System (ECWCS). Newer versions of this rainwear lack the Gore-Tex label and appear to be made from a proprietary 3-Layer waterproof/breathable fabric of some kind. Like many of the surplus options I’ve discussed in this series, the surplus Paclite shells sold for about half the price of commercial Paclite garments. However, these garments have no warranty, and the new 3-Layer fabric may not represent as much of a value as the original Paclite versions did. These shells are an option if you need camouflage for hunting, but given the range of excellent camouflage waterproof/breathable garments available from premium hunting brands like Sitka, FirstLite and Kuiu it’s hard to endorse these surplus rain shells as strongly as I have the other elements of the Army’s cold weather system.

[If you do decide to go the surplus route for rainwear, keep in mind that these layers are sized to fit over other clothing so they do run big. For pants, order your regular size. Jackets are sized to fit over body armor so you’ll want to order a size down for general outdoor use].

Simplicity is best with rainwear. You want clothes that keeps you dry but don’t have a lot of bells and whistles that will weight you down. Here are the basics:

Jackets will have an adjustable hood, full front zip, adjustable velcro cuffs and a couple chest height pockets that you can get your hands  into while wearing a pack with a hip belt. Hip length or longer is preferred with a drawcord hem that you can tighten or loosen to control ventilation. The hood should adjust to fit snugly around your face and follow your movement as you turn your head from side to side.

Pit zips offer increased ventilation to cool your core.
An adjustable hood follows your field of view.

Underarm zippers are a nice feature. These pit zips allow you to open up the inside of the jacket to allow lots of airflow. If you’re really sweating it is nice to be able to open the zips and get some fresh air moving inside your jacket to cool yourself down.

Rainwear doesn’t typically require the reinforced shoulders or elbows that you might see on waterproof/breathable mountaineering hard shells. These add unnecessary weight and bulk.

You do need pants. In warm weather you may be able to get away with a rain jacket, shorts and a soaked backside, but in cooler weather you absolutely need a pair of waterproof pants. Likewise, if you are spending the day fishing out of a canoe the only way to keep yourself dry is to wear rain pants. You need a pair of rain pants. Buy them. Seriously.

Ankle zips are a must in rain pants. Scuff guards (right) help durability.

At a minimum, pants should have an elastic, drawcord waist and zippers at the ankles. Ankle zips make it easier to get pants on and off over boots. Longer zips work better for dressing or undressing but are more likely to let in water. Shorter zips are drier.

Other features that can be nice on pants are pockets, scuff guards on the inner hem, heavier face fabric on the seat and knees, and a fly for the fellas. These features add utility and durability at the price of extra weight and bulk.

Like the soft shell layer, your rain layers should be sized to fit comfortably over all your insulating layers. This means for the top you’ll need to be able to layer over baselayer, lightweight fleece, midweight jacket and windbreaker. For bottoms you’ll need to fit over baselayer and lightweight fleece. For some people this will mean going up a size from what you normally wear. It’s important to make sure that whatever you choose will fit over all your other layers without limiting your comfort or range of motion.

Backpacking Great Smoky Mountains National Park and staying dry under a GoLite umbrella. On hot and humid days an umbrella is the best option for keeping dry.

The Umbrella and Some Final Tips for Rainwear Comfort
Back at the very beginning of this series I mentioned how influential Ray Jardine’s book Beyond Backpacking had been on my thinking about ultralight backcountry travel. One of the more unconventional recommendations that Jardine makes is to carry a lightweight trekking umbrella for use in most rain conditions. I have a GoLite umbrella from the mid-2000s that goes on every backpacking trip I take. The umbrella completely solves the problem of overheating in rainwear. In virtually all rain conditions you’re are able to keep dry under the umbrella while wearing fully breathable clothing–sometimes just baselayer and shorts. I heartily endorse using an umbrella whenever you can. GoLite is no longer in business, but as far as I can tell, the Euroschirm Swing Liteflex Trekking Umbrella is the same model. Every backpacker should have one.

Of course, if you need to use both your hands, say while paddling a canoe, the umbrella doesn’t do you any good. And if the rain is blowing sideways an umbrella won’t keep you dry. In high winds the thing is likely to turn inside out and blow away. These are the conditions that will force you to put on your waterproofs.

Ultralight backpacking. Trekking umbrella ready for action. Big Creek, GSMNP.

When you do, there are a couple things you can do to try to stay comfortable. First, adjust your clothing. Remove an insulating layer if you can. You’ll be warmer inside your raingear and you want to avoid overheating and sweating. It’s better to be a little bit cool than to let yourself get sweaty.

Second, try to keep your skin from touching the waterproof membrane on the inside of the jacket. If it’s cool enough, wear your lightweight baselayer top and bottom. This thin layer of lightweight wicking fabric between your skin and the waterproof coating can do a lot to improve your feeling of comfort. You won’t feel as clammy and your body heat will be able to dry your baselayer quickly once your exertion level drops off.

Of course, if its an 70 degree summer day in the Boundary Waters you aren’t really going to be keen to wear your baselayers. In this case, the best you can do is ventilate your rainwear as much as possible to try to keep your body cool and prevent heavy perspiration. If you have pit zips, try opening them up, loosening the hem on your jacket and opening the front zip as low as you can without letting rain in.

These tips don’t guarantee comfort, but they will help in the borderline situations that have you wondering if you’re better off with raingear or without.

Buy This, Not This
Buy a Gore-Tex Paclite rain jacket and a pair of Paclite pants made by a major outdoor brand. Make sure your jacket has a fitted hood that moves with your head. Pit zips are a nice feature in jackets and ankle zips are essential in pants. Size your shells so you can wear them over the top of Layers 1-4 of the clothing system. If Gore-Tex isn’t in your budget, buy an affordable set of breathable rainwear from a reputable outdoor brand. Whatever waterproof shells you buy should be backed by good warranty. Buy rain pants.

Buy a trekking umbrella.

Don’t buy non-breathable rainwear. Don’t buy heavy mountaineering hard shells. Don’t buy rainwear with hung liners. Don’t buy waterproof/breathable shells unless they are backed by a lifetime warranty against defects in materials and manufacturing.

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