The Great British Outdoors How do breathable waterproof fabrics work?
Most breathable waterproof fabrics contain a membrane, which has millions of microscopic pores that are up to 20,000 times smaller than a drop of water, but large enough to let the molecules of water vapour to get trough. Both waterproof and breathable fabrics have one goal – to keep you dry and comfortable. These fabrics resist to water penetration using a membrane or a coating that act as a barrier between you and elements while allowing your sweat to escape from the inside of the fabric to the outer layers. Some fabrics will prioritise certain properties over others and can be less breathable but more waterproof or other way round, depending on what activity it’s designed for.
Ratings of waterproofness:
- 1,500mm rating is a minimum that clothing fabric must have to be called waterproof by British standards. But a fabric with this rating won’t withstand much more than a very light and short exposure to wet.
- 10,000mm – 15,000mm A fabric with this rating will cope with most downpours, but it will begin to soak trough over time if applied pressure, such as sitting, kneeling and a heavy backpack.
- 20,000mm and higher is the best rating for prolonged wet conditions when carrying a heavy load.
| Rating | Resistance | Weather conditions |
| 5,000mm – 10,000mm | Low to average resistance | Very light to moderate rain / Dry snow / No pressure |
| 10,000mm – 15,000mm | Average to good resistance | Moderate rain / Wet snow / No pressure to low pressure |
| 15,000mm – 20,000mm | Good to high resistance | Heavy rain / Wet snow / Low pressure |
| 20,000mm + | Highest resistance | Heavy rain / Wet snow / High pressure |
Breathability ratings
While waterproof breathable fabrics resist to external moisture coming in, it also allow perspiration vapour to pass through to the outer layers and are best for intensive activities when waterproofing is necessary. Non breathable waterproof fabrics are best used in the most extreme weather conditions, when not high intensity activity, but waterproofing is essential. While these fabrics offer very high weather protection, they don’t allow internal moisture vapour to escape, which result of overheating and becoming wet from your own sweat. Breathability rating indicates how many grams of moisture vapour can pass through a square meter of the fabric material in 24 hours.
| Rating | Performance | Use |
| 5,000 g/m2 or less | Poor breathability | Camping / Not suitable for high intensity activity |
| 10,000 g/mm2 | Moderate breathability | Easy walking / Not suitable for intensive activity |
| 20,000 g/mm2 | Good Breathability | Backpacking / Running / Climbing |
Waterproofing seams
Even the best waterproof jackets won’t be waterproof without waterproofing it’s seams where needle punctures in the fabric will eventually let water sneak inside. Most water resistant clothing has either sealed or taped seams. Another method used for waterproofing seams is welded seam technology, which means that multiple fabric pieces are bonded together by using heat and pressure. Most manufacturers will specify their seam sealing method used on their product.
Popular waterproof breathable fabrics
- GORE-TEX
is most most established waterproof membrane that consists of stretched polytetrafluoroethylene (PTFE) which is also known as Teflon. This membrane is bonded with fabrics in various ways making them completely waterproof and windproof. GORE-TEX comes with several characteristics that make these fabrics to be considered as a membrane, a laminate and a technology since it comes in variations that are used for several purposes with the main differences of breathability and durability like GORE-TEX Active, GORE-TEX Pro, GORE-TEX Shakedry, GORE-TEX Paclite and GORE-TEX C-KNIT
Pros: Reliably waterproof, breathable, windproof, durable, light
Cons: Can be expensive, not as soft as other fabrics, functions best when body is hot, not as breathable as some other fabrics
Pertex Shield fabrics are using PU film coating for lightweight waterproof protection and a DWR treatment that protects against rain and snow and maintains breathability. The versatile 2.5 and 3-layer constructions combine highly packable lightweight fabrics with waterproof, breathable and windproof membranes that are great for active outdoors.
Pros: Lightweight, very packable, soft feel, highly breathable, waterproof
Cons: Not as durable as some other fabrics, not as waterproof as some other fabrics
eVent fabrics are using their dry system called DirectVenting™ which doesn’t require you to start sweating for it to work properly. It makes it possible for your sweat to escape instantly without letting moisture in thus keeping you dry and comfortable.
Pros: Excellent breathability, Waterproof
Cons: Expensive, can feel cool on a windy day
Paramo Nikwax Analogy is a highly breathable and unique system of water transfer control, where the idea of insulation and waterproofing comes from observations of how animal’s fur works. It consists from three components – two layers of fabric and a Nikwax TX Direct treatment waterproofing agent which applies a water repellency to every fibre causing the garment to treat water directionally, deflecting at least 90% of water that hits it.
Pros: Exceptional breathability, good insulation, quick drying, soft fabric, long lasting (if cared for properly)
Cons: Not as durable as other fabrics, heavier than most other fabrics, not as waterproof as some other fabrics, fabric needs frequent Nikwax reproofing
North Face Futurelight is using a new technology where a membrane is created with polyurethane solution sprayed from over 200,000 nozzles onto a surface in nanospinning process.This membrane then is used to create a breathable, elastic and waterproof film that is applied to the front and back of the garments. This nano fiber is small enough to keep water out while allowing the air flow through the membrane. This method allows for variable thickness within a single piece of garment, creating various soft to touch design options for freedom of movement and comfort.
Pros: Excellent breathability, elastic, soft, waterproof, light
Cons: Expensive, can feel cool on a windy day
North Face DryVent is using polyurethane (PU) coating that is applied in a thin, even layer on the back of the face fabric, while front of the face fabric is treated with a DWR finish that repels water droplets from the surface. Each multi layered textile is designed to allow water vapour to escape through to the outside.
Pros: Flexible, light, waterproof, breathable
Cons: Not as durable as some other fabrics, not as waterproof as some other fabrics
Patagonia H2No is typically made of a water repellent shell and waterproof – breathable membrane. This is at the base of design as there are three variations – 2 layer, 2.5 layer and 3 layer H2No fabrics which differ in durability, breathability, lightness and waterproof performance. All H2No fabrics undergo series of tests which simulates a lifetime of use and abuse to ensure reliable quality.
Pros: Waterproof, durable, breathable, not as stiff as GORE-TEX
Cons: Not as breathable as some other fabrics
Polartec Neoshell is created from a hydrophobic, microporous, PU membrane with controlled range of pore sizes, offering the stretch of a PU film and the breathability of a microporous structure. This construction allows for a excellent moisture vapour release while remaining waterproof.
Pros: Flexible, waterproof, light, highly breathable
Cons: Not as durable as some other fabrics, heavier than some other fabrics
