Waterproof Fabrics 101

At the heart of any “rainproof” jacket or shell is a technical fabric designed to stop liquid water coming in while letting water vapour (sweat) escape. Two key performance metrics matter:

💧 Waterproof rating (Hydrostatic Head):
Measured in millimetres (mm). The higher the number, the greater resistance to water pressure. Above 10,000 mm is considered waterproof; elite hardshells sit well above 20,000–30,000 mm. 

🌬 Breathability (MVTR):
Shown as grams of water vapour that can pass through a square metre of fabric in 24 hours (g/m²/24 h). Higher numbers mean better moisture transport — important when you’re active. 

These two qualities are a trade-off: super high waterproofing often reduces breathability, and vice-versa.

🏆 The Heavy Hitters — Gore-Tex & eVent

GORE-TEX — The Benchmark

Arguably the most recognisable name in waterproofing, Gore’s membranes use expanded PTFE (ePTFE) with tiny pores that block rain but let vapour out. 

Typical performance:

• Waterproof: usually >28,000 mm — very high resistance.
• Breathability: varies by subtype: ~15,000 g for lightweight shells to ~25,000 g for Pro versions. 

Use cases:
Great for mountaineering, extended backpacking, rough wet climates, and situations where you’ll be caught in heavy rain for long periods.

Pros: rugged, proven durability, widely supported by brands.
Cons: breathability can lag behind some competitors, especially for intense aerobic use.

eVent — Direct Venting Champion

eVent uses a similar ePTFE base but with Direct Venting™ technology — meaning moisture doesn’t need to condense first; it passes straight through. 

Typical performance:

• Waterproof: around 30,000 mm.
• Breathability: 15,000–25,000 g (some versions push higher). 

Use cases:
Perfect for high-output activity — trail running, mountain biking, fast hikes — where sweat evacuation matters as much as rain protection.

Pros: excellent breathability, quick moisture escape.
Cons: needs more careful laundering and DWR care to maintain performance; historically less market presence than Gore-Tex. 

⚡ Polartec & Alternative Technologies

Polartec NeoShell® — Breathability First

Polartec’s NeoShell uses an electrospun polyurethane membrane with significant air permeability, trading some waterproof rating for extreme breathability. 

Performance snapshot:

• Waterproof: about 10,000 mm (still waterproof for many conditions).
• Breathability: up to 30,000 g or more. 

Use cases:
Ideal for active aerobics in rain, ski touring, cycling, or day hikes where evaporative comfort is a priority and storms are intermittent.

Pros: superb comfort, stretch potential, ideal for variable intensity.
Cons: lower waterproof ceiling — heavy downpours for prolonged hours may eventually soak through.

Polartec also offers “Power Shield” waterproof variants with stretch and varied performance for outdoor pursuits.

🧰 Other Technical Waterproof Materials Worth Knowing

Sympatex®

A closed, hydrophilic polymer membrane (no pores) that moves moisture at a molecular level. Offers good waterproofing and breathability and is fully recyclable. 

When used: hiking shells, eco-focused gear.

Dermizax® and Pertex Shield

Polyurethane membrane systems used mainly in European mountain gear. Often balanced around mid-tier waterproofing (~15–20 k) and solid breathability. 

When used: Alpine jackets where stretch and packability matter.

Proprietary Brand Systems

Brands like The North Face HyVent, Patagonia H2No, and Rab Proflex use their own versions of microporous or hydrophilic membranes. Performance typically sits below Gore-Tex/eVent in breathability or waterproofing but often at a friendlier price point. 

🎒 Real World Guidance — When to Choose What

🧠 Understanding the Trade-Off

There’s no perfect fabric — it’s always waterproof vs breathability vs durability vs weight:

• Highest waterproof ratings (>25k) often mean heavier, less breathable shells. 
• Top breathability (>25–30k) often has a lower waterproof ceiling or requires careful DWR maintenance. 
• DWR coatings matter: even the best membrane can “rain-soak” and lose breathability if the outer face wets out — so maintenance (re-applying DWR) is critical.