Why Waterproof Jackets Don’t Work

The truth is, that expensive jackets don’t work as most people expect them to work, especially in tough conditions.

If you’ve ever gone hillwalking or mountaineering and ended up wet through despite wearing a ‘breathable’ waterproof jacket, you’re definitely not alone.

Lots of people, quite rightly, expect their waterproof jackets to keep them dry and comfortable no matter what the weather throws at them and no matter how hard they’re working.

The truth is, that expensive jackets don’t work as most people expect them to work, especially in tough conditions.

What’s actually happening when we wear our waterproof layer on a rainy day in the hills…

How Breathable Waterproof Jackets Work

Breathable waterproof jackets are almost always made out of layered fabric that includes a microporous membrane with the ability to keep water out while allowing sweat vapour to pass through.

Fabrics like Gore-Tex keep water out BUT let sweat escape, and that’s important – an adult, walking uphill with a rucksack on will sweat up to 2 litres every hour.

So – after a brisk 2 hour walk uphill you could be holding 4 litres of moisture within your clothing unless you can release that moisture through breathable fabric or by venting.

Venting is great – if you can, choose jackets that have ‘pit zips’ and that are practical to open at the chest when your walking.

Waterproof Ratings & Breathability

A fabrics waterproofness is measured in a lab using a hydrostatic head test. This test determines how many millimetres of water a fabric can withstand in a 24-hour period before seeping through.

The higher the number, the more waterproof the fabric is.

Breathability is defined as the amount of sweat that can be let out through a fabric.

Breathability ratings are assigned according to the amount of moisture that can pass through a square metre of fabric in a 24-hour period.

Gore-Tex has a waterproof rating of 28,000mm and a breathability rating of 17,000g

That means in perfect conditions Gore-Tex is waterproof and will release 17 litres of ‘vapour moisture’ in 24 hours per square meter.

Do Breathable Waterproof Jackets Work?

No.

A waterproof jacket will have approximately 2 sqm of effective, breathable, surface area. Breathable waterproof fabric can release 0.7 litres an hour in absolutely optimum conditions.

While you’re walking uphill in the rain with your jacket done up tight most sweat will be released from your armpits and upper back, the amount of water vapour you produce will be greater than the fabric can release.

Your, very expensive, waterproof jacket becomes a ‘sweat box’, a trap for moisture – you’ll end up wet and uncomfortable.

AND your jacket will never, ever be operating 100% effectively after the first day you use it.

Dirty fabric can’t breath, fabric that doesn’t ‘bead’ doesn’t breath, fabric operating in less than perfect environmental conditions doesn’t breath very well.

So what the hell can you do to try and stay warm, dry and comfortable?

How to Wash a Waterproof Jacket

Dirty waterproof jackets simply don’t work as well – over time, grime and sweat clog the pores in the fabric, stopping it from ‘breathing’ effectively. When your jacket can’t release moisture, water vapour builds up inside, leaving you feeling damp and uncomfortable.

The Right Way to Wash a Waterproof Jacket

To keep your jacket breathable, it’s essential to clean it properly, avoid regular detergents – they can damage the fabrics waterproof coating (DWR). This is the gold standard…

  1. Brush off loose dirt and close all the zips.
  2. Clean your washing machine to remove detergent residues.
  3. Use a technical cleaner like Nikwax Tech Wash (it’s basically soft soap).
  4. Wash at 30°C – following the care label.
  5. Tumble dry on a low setting to reactivate the Durable Water Repellency (DWR) coating.

How to Reproof a Waterproof Jacket

When your jacket stops beading water and the top layer of fabric starts absorbing it, it starts ‘wetting out.’ This doesn’t mean it’s leaking, but it does mean the DWR finish is no longer effective, the fabric becomes WAY less breathable, trapping sweat inside.

Restoring a Water Proof Jacket

To reproof your jacket:

  1. Wash it with a technical cleaner (as above).
  2. Use a reproofing treatment like Nikwax TX.Direct Wash-In
  3. If your jacket has a liner, opt for a spray-on treatment to target the outer fabric.
  4. After applying the treatment, tumble dry on low heat to set the DWR.

Reproofing regularly will keep your jacket performing its best.

FAQs – Why Waterproof Jackets Don’t Work

Why does my waterproof jacket feel wet inside? Because of condensation – you’re basically a sweaty beast – especially if the jackets breathability is compromised by dirt or a worn-out DWR finish.

How often should I wash my waterproof jacket? Wash it whenever it gets visibly dirty or if it’s no longer beading water effectively.

Do I need to reproof my jacket every time I wash it? No, but reproof when water stops beading on the surface or after every few washes.

Can I use regular detergent to wash my waterproof jacket? Avoid regular detergents as they can strip the DWR

Understand the limitations of breathable waterproof jackets and learn how to care for them, you WILL stay drier and more comfortable on your outdoor adventures.

Look after your jacket, vent whenever you can, walk a bit slower uphill.

No jacket is truly waterproof in a hillwalking or mountaineering setting – it doesn’t matter how much money you spend or how well you look after your kit, you’re going to be moist some of the time.

Wild Wales in North Wales

Wild Wales helps people have brilliant adventures in North Wales.

We specialise in Mountain Walking and Wild Swimming.

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