The Ultimate Guide to Choosing waterproof breathable membrane

Mar. 03, 2025

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Waterproof-Breathable Fabrics Explained | Trail & Crag

If you've ever found yourself trying to choose between two waterproof jackets and wondering what was meant by 'tricot', 'DWR, or 'water-resistant', this article is for you. In this gear guide, I'm going to go into the technology used in waterproof fabrics and the things you might want to consider when choosing your next piece of rainwear. Just know that it's going to get a little nerdy as this is the most technical article in a whole series on waterproof garments. If you are looking for something more general, like how to choose a rain jacket or an article explaining the differences between a soft shell and a hard shell, I have articles on those too.

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Waterproof vs water-resistant

To ensure proper protection in the conditions you expect to face, it's important to know the difference between the three levels of water protection afforded by fabrics. To be clear, the industry has yet to develop a standardized system for rating the water resistance of fabrics, and what I have done here is use designations where there is the most consensus among brands. Thankfully, many manufacturers have performed a more or less standardized test, which makes it possible to make comparisons. In a hydrostatic head test, an open-ended cylinder is placed on top of a piece of fabric and slowly filled with water. Results are measured in how much water the material can be exposed to (in milimeters) before it begins to seep.

Water-resistant (0 to 1,500 mm)

'Water-resistant' means that a fabric is tightly woven or manufactured in such a way that it resists penetration by moisture. But that doesn't mean much. A garment made from water-resistant fabric won't keep you dry in much more than a misty morning fog or a little drizzle. This is the lowest level of protection against moisture. Water-resistant fabrics perform very poorly in hydrostatic head tests and usually aren't even tested.

Water-repellent (1,500 to 5,000 mm)

Water-repellent fabrics have one up on water-resistant fabrics in that they have a durable water repellent (DWR) coating which causes water to bead and roll off a jacket instead of soaking through it. This slows the speed at which a jacket becomes saturated in sustained rain. Because they don't have waterproof membranes, water-repellent fabrics are only good for keeping you dry in light rain and are not sufficient for rainwear.

Waterproof (over 5,000 mm)

A waterproof layer will protect you in moderately heavy to very heavy rain depending on its rating. In very wet conditions, a fabric rated to 10, 000 mm will keep you drier than one rated to 5,000 mm, but above 20, 000 mm there is little notable difference in performance. Garments deemed waterproof typically have a DWR-treated face fabric and a waterproof-breathable membrane. Beyond this, they also need to have sealed seams (taped or heat welded) to ensure that water doesn't get through the seams.

How do waterproof breathable fabrics work?

The fabrics used in technical rain wear typically have at least two layers: a waterproof breathable membrane and a permeable outer face fabric that protects the membrane.

A membranes acts as a barrier to water

At the core of every waterproof breathable fabric, there is a membrane which acts as a barrier to liquid water. These membranes come in two types: the first is porous and allows for air to pass through it while preventing the transmission of water droplets. The second, less breathable type of membrane is non-porous and allows for only water vapor to pass through it. Despite their functional differences, both types of membrane have to remain clean and unclogged if they are to 'breathe' at all.

The DWR-treated outer fabric helps the membrane to breathe

A waterproof membrane will usually stop breathing if the face fabric 'wets out' and becomes saturated in water. With nowhere to go, the water vapor in your perspiration then accumulates on the inside of your jacket, making you cold and sweaty. To prevent this, manufacturers treat their face fabrics with a hydrophobic Durable Waterproof Repellant (DWR), which causes water to bead up and roll off fabric instead of permeating it. The more effective the DWR, the better a fabric will breathe and keep you dry.

PFAS-free membranes and DWR

Up until recently, both the membranes and DWR found in waterproof fabrics relied on per- and polyfluorinated alkyl substances (PFAS) to repel water and make fabrics breathable. The problem with PFAS is that they do not break down over time and are harmful to the environment and people who can ingest them. To solve this problem, gear manufacturers have invested heavily in the development of PFAS-free membranes and DWR.

Nikwax was the first major brand to launch a range of PFAS-free products with TX.Direct Wash-in and Direct.Dry (factory-applied DWR), but many others have since followed their example. Gear Aid now make their own PFAS-free DWR called Revivex, and at least a few fabric manufacturers, like Gore-Tex, have developed their own PFAS-free DWR. But it's not just DWR that has traditionally contained PFAS. Most membranes are still made using PFAS, although the fluorine-free trend is gaining momentum here too with eVent, Gore-Tex, and several clothing manufacturers developing PFAS-free membranes.

What are the downsides to PFAS-free fabrics and DWR?

As can only be expected, there are some downsides to PFAS-free fabrics and DWR. The most significant of these is that PFAS-free garments have to be washed and reapplied with DWR more regularly. If in the past, you washed and reapplied DWR to your rain wear only once a season, you might find that you need to reapply DWR two or three times a season. But for most consumers, that will be a small price to pay for owning a more sustainable product. Reapplying DWR is also pretty easy as I explain in my guide on how to apply DWR.

Which brands make garments that are PFAS-free?

PFC-free DWR and face fabrics are now the norm, but only a few brands are using PFC-free membranes in all their garments. Patagonia and Fjällräven are two brands that stand out in having already achieved this. Other brands, like Rab and Outdoor Research, have committed to being 100% by the end of and have already made progress in removing PFAS from most of their products. There are also those brands that will only start using PFAS-free because the law demands it.

Brands that are completely PFAS-free Brands that are close to PFAS-free Patagonia Rab Fjällräven Outdoor Research Houdini Arc'teryx Jack Wolfskin

2L, 2.5L and 3L fabrics

Most waterproof fabrics are constructed in one of three ways: with 2 layers, 2.5 layers, or 3 layers. Each has its own pros and cons, and differs from the others in terms of breathabiity, durability, weight and bulk.

2L fabrics

Traditionally, 2-layer shells have had a face fabric bonded to a waterproof-breathable membrane with a loose (typically mesh) protective liner hanging inside them. Although more affordable, these mesh-lined 2L garments are generally heavier, bulkier, and less comfortable than 2.5L and 3L equivalents. However there are now also a few innovative 2L fabrics which use a textured membrane that increases abrasion resistance and makes an additional protective layer unnecessary. Garments made with these fabrics don't need a mesh lining, meaning that they can be made lighter and less bulky.

2.5L fabrics

Like 2L and 3L fabrics, 2.5L fabrics also have DWR-treated face fabric and a waterproof-breathable membrane. But instead of having a separate mesh lining like most 2L fabrics or an inner layer bonded to the membrane like 3L fabrics, 2.5L fabrics have a thin protective coating (the 0.5 layer) painted onto the inside of the membrane. In the past, these coatings weren't as good at absorbing and transmitting perspiration as a tricot lining, and many 2.5L shells left wearers feeling a bit clammy when they were worn next to skin. But recent developments in 2.5L fabric construction have helped improve the clammy factor, and some 2.5L shells are now almost as comfortable as 3L equivalents.

3L fabrics

In 3-layer fabrics the waterproof-breathable membrane is sandwiched between the face fabric and a protective inner lining. Again, the main purpose of this last layer is to prevent sweat and oils from clogging the microscopic holes in the membrane ' something that would hinder breathability and make the wearer clammy with perspiration. It is this ability of the lining to prevent a membrane from becoming fouled that gives 3-layer fabrics an advantage over comparable 2.5 layer fabrics. The disadvantage of 3L fabrics is that they are slightly heavier than 2.5L fabrics (2L garments have a separate inner lining and can actually be heavier). As with 2L and 2.5L fabrics, the degree to which a 3L fabric is breathable depends on the type of waterproof-breathable membrane.

Waterproof-breathable membranes

Making a garment waterproof isn't difficult, but making it waterproof and breathable is. To overcome this challenge, gear manufacturers have all turned to the same solution, a waterproof-breathable membrane. The original ePTFE membrane was produced by Gore-Tex, a brand that dominated the market for decades. 60 years on, there are now four different types of waterproof-breathable membranes and a dozen companies making them. This is what you need to know about the pros and cons of each.

Air-permeable membranes

Because they are porous, air-permeable membranes allow for the transmission of air and water vapor molecules, making them significantly more breathable than vapor-permeable membranes, which don't allow air to pass through them. Given how important breathability is for preventing the build up of sweat during exercise, this type of membrane is often a better choice for physically intense activities.

ePTFE

Expanded polytetrafluoroethylene, or ePTFE for short, is the material that was first used in waterproof-breathable membranes. Because it doesn't need to be as thick as polyurethane, it can be made thinner and more breathable than polyurethane film equivalents. The downside to ePTFE membranes is that they can become fouled more easily (impairing breathability) if exposed to oil and dirt and need to be washed regularly to ensure breathability and longevity. Products include Gore-Tex Pro and eVent, the two most expensive outdoor fabric brands on the market.

Gore-Tex Pro
eVent

Electrospun polyurethane

Because they are non-porous, regular PU film membranes (described under vapor-permeable membranes) are inherently less breathable than ePTFE membranes. To overcome this limitation and improve breathability, a few fabric manufacturers have started using electrospun polyurethane to make porous membranes. The result is a type of air-permeable membrane that is almost as breathable (or even as breathable) as ePTFE membranes and only slightly less waterproof. Fabrics include Polartec NeoShell, Outdoor Research AscentShell, and The North Face FutureLight.

Polartec NeoShell
Outdoor Research AscentShell
The North Face FutureLight

Vapor-permeable membranes

Unlike air-permeable membranes, vapor-permeable membranes are non-porous, meaning that air cannot pass through them. To achieve breathability, vapor-permeable membranes allow the transmission of water vapor through molecular wicking. This makes them inherently less breathable than air-permeable membranes, although the degree to which they are less breathable varies significantly between the two types of vapor-permeable membrane.

ePTFE-PU

Unlike Gore-Tex Pro, which has an ePTFE-only membrane, regular Gore-Tex features an ePTFE membrane bonded to a thin PU film. The purpose of the latter is to help prevent oil and dirt from clogging the membrane, the achilles heel of true ePTFE membranes. The result is a membrane that is less breathable than ePTFE membranes but more breathable than PU membranes. This type of hybrid membrane also splits on the difference on resistance to fouling and sits between the two in terms of price. Achieving a happy middle ground in all aspects of performance, Gore-Tex is still the most popular of waterproof-breathable fabrics.

Gore-Tex

Polyurethane film

Because they don't incorporate any other membrane layers, PU film membranes have to be thicker to ensure the same level of waterproofness. Being thicker and entirely non-porous, these membranes are less breathable than other types of membrane, especially in humid conditions. But PU films also have their advantages: they are very durable and don't become fouled by dirt and oil as easily as ePTFE membranes. And they are more affordable than any other type of membrane, making them a popular choice for proprietary fabrics like Patagonia H2No, Marmot NanoPro, and Columbia OmniShield.

Patagonia H2No
Marmot NanoPro
Columbia OmniShield

How to care for waterproof breathable fabrics

A waterproof jacket will keep you dry and warm for many years if properly cared for. Here's how you get the most out of it.

Wash your rain gear regularly

With use, a garment will be exposed to dirt, sweat, sunscreen and insect repellent, all of which can reduce the effectiveness of a DWR application. Fortunately, restoring the breathability of a garment can be as easy as washing it. Use a suitable soap like Nikwax Tech Wash and make sure to read the manufacturer's washing instructions on the label. Most jackets can be machine washed, but you should always check first.

Don't use fabric softener

Fabric softeners and bleach can damage the membrane in a waterproof jacket, so you should keep these products away from your rain wear. This actually applies to most technical clothing, which is just another reason that it's best to wash your synthetic outdoor clothes (all of which should be washed with tech wash) in a separate load if possible.

Reapply DWR when needed

After a while, your jacket's DWR will become noticeably ineffective even after you wash it. Instead of beading up on the surface, water will permeate the face fabric, causing the garment to 'wet out' and stop breathing. This is a sign that it is time to reapply DWR. But this is quite easy. With waterproof jackets, you wash in the DWR, using a product like Nikwax TX Direct. Again, read the label so that you know how to wash and dry the garment without damaging it.

Get more advice from this gearhead

How to choose a waterproof and breathable jacket - Alpkit

Staying dry when hillwalking, running, climbing and riding is a constant challenge. The right waterproof jacket completes your layering system with a breathable, waterproof outerlayer.

A waterproof, breathable jacket is a critical part of your layering system. This guide is designed to answer every question you might need to ask yourself when choosing a waterproof jacket for hillwalking, climbing, running or riding.

How to choose a waterproof and breathable jacket

What are you going to use it for?
How waterproof does it need to be?
How breathable does it need to be?
Do I need a 2, 2.5 or 3 layer waterproof?
Why do you need an insulated waterproof?
What is a DWR and do I need to think about it?
How durable does it need to be?
Are weight and pack size important to me?
Will it be comfortable for what I need it for?
What other features do I need?

What are you going to use it for?

Deciding what you're going to use your waterproof jacket for is your first step to narrowing down the options. You might need a waterproof jacket for very specific activities like hillwalking, cycling or trail running, or maybe you just want one jacket that will cover as many activities as possible.

Waterproof jackets will generally fit into one of three categories depending on their features and what type of performance they prioritise: lightweight, flexible and packable jackets for high intensity activities; highly durable and fully featured for harsh mountain conditions; and all-rounders that strike a balance between the two.

How waterproof should my jacket be?

For prolonged periods of heavy rain, your jacket should have a hydrostatic head of at least 10,000mm (you may see this listed as 10K). Hydrostatic head (HH) is the industry standard for waterproofing. Essentially, the higher the HH rating, the longer your waterproof will keep out the rain.

It's also a measure of how much water pressure your waterproof can withstand. Heavy rucksack straps, stretching and kneeling increases the water pressure on your jacket. Because of this, waterproof jackets and waterproof trousers need a higher HH than tent flysheets which benefit from being stretched under tension.

1,500 ' The agreed industry standard at which a fabric is considered 'waterproof'. Real world conditions are another matter though!

5,000 ' The rating often used for ski jackets and salopettes, enough to keep out snow and light showers. Our 0Hiro Primaloft® insulated jacket and Cirrus smock use 5K and 8K membranes respectively for extra shower resistance.

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10,000 ' Very good performance, enough for extended periods of heavy rain. This is the lowest rating we use for our waterproof jackets. Our Argonaut, Solace and Atalanta jackets both use a 10K waterproof membrane.

20,000 ' Excellent performance, sufficiently waterproof for all day rain, wearing with heavy packs and strong winds. Our Gravitas, Balance, Fortitude and Pulsar jackets and Parallax, Equinox and Nautilus trousers all have 20K performance.

30,000 ' The highest performing fabrics for the very worst conditions. Reliably waterproof even in serious mountain conditions and storm-force winds. The Definition mountaineering jacket is our only waterproof jacket with a 30K rating.

How breathable should my waterproof jacket be?

The higher the intensity of your activity, the more breathable your jacket needs to be. Your body naturally produces sweat and moisture vapour to maintain an even temperature. If your jacket isn't breathable enough, this moisture can't escape, making you cold and clammy (think about every time you've ever worn a cheap plastic poncho). As well as being uncomfortable, getting cold and damp can be dangerous in mountain environments.

We measure breathability by something called Moisture Vapour Transmission Rate (MVTR) which is counted in grams per square metre per day (g/m²/24hrs).. You will often see MVTR listed as the second number after HH, e.g. 30K/20K. As a rough guide:

5,000 ' Good breathability, enough for more stationary activities.

10,000 ' Very good, breathable enough for moderate activity like walking, gentle bike rides and paddle sports. (Argonaut, Sigma, Atalanta) and Cloudburst waterproof trousers

20,000 ' Excellent breathability, ideal for strenuous hillwalking, mountaineering, mountain biking and running. (Balance, Fortitude, Definition and Pulsar jackets, Parallax and Nautilus trousers)

30,000 ' Exceptionally breathable. The highest performing fabrics for high intensity running and riding on steep terrain. (Gravitas)

Do I need a 2 Layer, 2.5 Layer or 3 layer waterproof?

Breathable waterproofs - Stops the rain coming from the outside to the inside while letting moisture move from the inside to the outside. Waterproof jackets and trousers are constructed in layers: The inner layer, membrane, and outer layer.

The inner layer provides next-to-skin comfort, wicks moisture and protects the membrane from dirt and abrasion.
The membrane allows moisture vapour to pass through to the outside and stops rain from passing from the outside to the inside.
The outer layer protects the membrane from dirt and abrasion and creates a hydrophobic layer to enhance breathability.

Generally speaking, the higher the number of layers the more reliably waterproof the construction is as the waterproof membrane (the important bit) has more protection. Breathable waterproof fabrics are actually sandwich of multiple layers bonded together.

2 Layer: A face fabric and membrane, usually protected by a separate mesh or nylon fabric. This is a heavier and less reliable construction for waterproof jackets so we don't use 2-layer fabrics for any of our waterproofs.

2.5 Layer: A face fabric and membrane with a printed backer for protection. 2.5 Layer fabrics are usually light, flexible and extremely packable. Our Argonaut, Atalanta and Pulsar jackets and Parallax trousers use this construction.

3 Layer: A face fabric, membrane and backer fabric with the most reliable membrane protection. Our Gravitas, Balance, Fortitude and Definition jackets and Nautilus trousers all use this construction. The Gravitas is one of the lightest 3-layer waterproofs available.

Why do I need an insulated waterproof?

An insulated waterproof jacket combines the features of both insulation and waterproofing, making it an incredibly versatile piece of outdoor gear with some key benefits:

Protection from rain: A waterproof outer layer ensures that rain, sleet, or snow doesn't penetrate the jacket, keeping you dry.
Warmth: Insulated jackets contain materials, either synthetic or natural (like down), that trap air and retain body heat. This makes them ideal for cold conditions.
Versatility: Because it serves dual purposes, an insulated waterproof jacket can be ideal for varying weather conditions, from cold and dry to cold and wet.
Improved Comfort: Staying both dry and warm enhances comfort, which can lead to a more enjoyable outdoor experience, whether you're hiking, skiing, or simply commuting in cold, wet weather.

Our insulated waterproof jacket is called the Solace Mens and Solace Womens. Supremely versatile, the Solace can be used as a walking jacket, a ski jacket, or for instant warmth after a winter swim or ride. It's got hand warmer pockets and glove-friendly cuffs to accommodate ever-cooling extremities. Made with 100% recycled lining, 70% recycled insulation and a PFC-free DWR so it won't leak nasties into the environment. A winter one-stop-shop layer. For many people and activities, there are compelling benefits for combining insulation and waterproofing into a single jacket.

What is DWR and do I need to think about it?

Waterproof jackets use a durable water repellent (DWR) treatment to stop the fabric from absorbing water and 'wetting out'. Historically, these treatments contained chemicals called fluorocarbons (or PFCs) which have been found to build up in the environment with a number of harmful effects. Because of this, we've been moving all of our waterproofs to completely PFC-free DWRs. These new treatments require a bit more care (washing and reproofing) but we think it's worth it to reduce our environmental impact.

How durable does my waterproof need to be?

If you're only using your waterproof for low level walking, running and road cycling, durability probably isn't your primary concern. But activities like hillwalking (where scrambling may be involved), mountain biking and even gravel cycling (lots of thorny hedgerows!) require more durable fabrics. Climbing and mountaineering waterproofs need to be particularly hardwearing to survive sharp climbing gear, heavy packs and repeated abrasions from rocks.

It can be hard to compare waterproofs for durability as there so many different factors which can affect how hardwearing a fabric is. For instance, our Balance waterproof is extremely tear resistant due to the fabric's high levels of stretch, and the Definition is more abrasion resistant because it uses a 'plain weave' fabric that's less easy to catch. That said, there are several things you can look out for as a rough guide.

Weight: Heavier jackets generally use more durable face fabrics and backer fabrics.

Denier: This is the thickness of the yarns used to make the fabric. Face fabrics with a higher denier number will often be harder wearing. For example, our Gravitas running waterproof uses 7 denier (D) nylon, whereas the Fortitude hillwalking waterproof uses 70D nylon.

Material: Ripstop fabrics have a grid of higher denier yarns woven through them which stop long tears from developing. Our Definition uses Nylon 6,6, a 'high tenacity' material that is more tear and abrasion resistant than regular nylon.

Are weight and pack size important to me?

For running and road cycling, you probably want a waterproof that's as light and packable as possible, fitting neatly into running packs and jersey pockets without slowing you down. You will need a more durable waterproof for hillwalking and multi-day backpacks but may still prefer a lighter jacket that doesn't add lots of weight or take up too much pack space ' particularly in summer.

Will it be comfortable for what I need it for?

You may also want to think about the fabric and the type of fit and cut that will be comfortable for your chosen activities.

Fabric

Lightweight, flexible fabrics are more comfortable for running and moving fast. Stretch fabrics give you greater freedom of movement for climbing, scrambling and leaning over handlebars. More rigid fabrics offer a greater feeling of protection in high winds.

Fit

Think about how many layers you're likely to wear underneath. 'Regular Fit' jackets will give you more space for winter layers, while 'Slim Fit' jackets are usually designed to be worn over just a base layer or thin fleece.

Cut

A longer cut offers greater protection but more 'active' cuts are less restrictive for high strides and climbing moves. Mountaineering jackets are usually designed to allow you to raise your arms without your jacket riding up. If you're likely to wear your jacket for cycling, make sure it has a drop hem that covers your bum and that the sleeves are long enough when you reach forward.

What other features do I need?

Pockets

Do you need pockets? Probably. Pockets are always useful. Fill them with trail mix, bits of cord, magic rings. But what size do they need to be? Do you need pockets big enough to fit a map or chunky winter gloves? Can you access them above a harness if you're likely to use your jacket for mountaineering?

Hood

Make sure it's a good fit and has adjustors that cinch it in close to your head. A wired/stiffened peak improves visibility and protection in strong winds. If you're likely to wear your jacket for climbing or mountaineering, make sure your waterproof has a 'helmet compatible' hood that fits your climbing helmet.

Our Fortitude hillwalking jacket features a fully-adjustable hood with a wired peak for bad weather protection

Zips

Water-resistant zips (like YKK Aquaguard®) will keep your pockets drier (although we'd still use a dry bag for electronics in a downpour). Make sure the main zip has a storm flap (this will either be a Velcro flap on the outside or a thin strip of fabric behind the zip). Two-way zips are useful for wearing with a climbing harness so you can belay easily.

Vents

Vents allow you to dump excess heat and sweat when you're overpowering your jacket. Usually these will be 'pit zips' under the arms but mesh pockets can also double up as vents in lightweight jackets. The Definition uses side vents which are easier to get to when wearing a climbing harness.

The best jacket is the one you look after

Whatever jacket you choose, look after it! That doesn't mean bringing it cups of tea in bed or tucking it in at night. Just make sure you wash it regularly and reproof it once or twice a year. The fanciest waterproof jacket in the world won't be very effective if it's covered in a year's worth of mud, dirt and skin oils. Here's why caring for your waterproof is important and how to reproof it.