Understanding which type of outdoor clothing you need depends greatly on the type of activity and climate you expect to encounter. For instance, a 5k, 2-Layer water-resistant jacket that protects you from light rain on a moderate walk in the South Downs will react very differently to the challenges of a high energy ascent during a sustained downpour in the Scottish Highlands.
With this handy guide, we hope to give you a better understanding of the types of construction and technology available to help you select the right garment for your travels. Buying waterproof clothing need not be daunting - follow our advice and you will not go wrong! Please phone during our shop opening hours or email a question any time. We are here to help.
The vast majority of good-quality jackets on the market are technically water-resistant. A wellington boot is waterproof and if you’ve ever spent the day yomping around in a pair you’ll know that the thick rubber shell keeps the rain and muck from getting in but on the downside creates its very own micro-climate; often resulting in a pair of soggy socks and sweaty feet by the end of the day. Nothing gets in, but nothing gets out either.
The trick with waterproof clothing is to prevent rain moisture from getting in whilst allowing heat moisture (perspiration) to escape. This transfer of moisture vapour from the jacket’s interior, through to the face-fabric where it can evaporate in the open air reduces the build-up of sweat, which keeps under-layers dry and allows you to enjoy high energy activities in greater comfort and warmth.
Every brand has its own way of achieving this but the basic principle remains the same:
It’s all about the molecules…
In basic terms, each garment features a water-resistant membrane made up of micro-pores (in some cases over 9 billion per square inch!). These pores are so small that a single water droplet is unable to penetrate it. At the same time, a smaller water vapour molecule is able to pass right through, essentially enabling the layer to ‘breathe’ and drawing sweat to the outside. Think of a one-way street with larger traffic blocked from going one way yet smaller traffic allowed to pass in the opposite direction.
Membrane construction varies in density (pore size) with each garment carefully designed to perform in certain conditions, from light rain to heavy downpours. Each design is then rigorously tested to determine its waterproof rating – this provides us with a rough guide as to the level of protection the garment affords and thus the type of activities and conditions it is best suited to.
The Static Column Test is used to measure a garment’s waterproofness and provides us with a water column rating (anything from 1K – 40K+). The Static Column Test uses a 1-inch diameter cylinder positioned vertically over the material to be tested. Water is added to the cylinder and the point at which the material leaks (measured in mm) becomes the waterproof rating. So that 5K jacket you got for the South Downs leaked at the 5’000mm mark giving it a rating of 5K (or 5’000mm). Great in light showers but the density of those pores means it will let in water in a sustained downpour. Thinking of that spring trek around the Black Mountains? Then you’re going to want a jacket with a higher rating to ensure dryness.
There’s no hard and fast rule to determining the level of protection afforded by higher ratings as waterproofness is affected by the pressure of water (exacerbated by wind) working upon it. In real terms, a higher-rated waterproof construction will keep moisture out for longer.
As a rough guide:
Protection in light showers. Great around town and casual hikes with no heavy storms in the forecast. Will eventually leek when exposed to sustained downpours.
A solid level of waterproofing - the kind of jacket the experienced walker and outdoor professional would want in their kit.
High-alpine and expedition level gear. Built with storm-level protection to withstand sustained downpours and high winds. These will give you guaranteed protection under pressure.
In order to keep you dry and comfortable a waterproof jacket must be able to repel water moisture from the outside and let moisture vapour escape from the inside. Construction differs between brands and intended use, with jackets geared towards rock-climbing and winter sports often featuring a more rugged, abrasion-resistant fabric than casual lightweight rain shells. The most obvious thing to look for when choosing a waterproof jacket is the layering – these typically fall within three categories: 2-layer, 2.5-layer, and 3-layer constructions.
In each case, these comprise a DWR face fabric with a waterproof/breathable membrane backer (such as Gore-Tex) with the main difference occurring in the liner or innermost layer. Here’s a quick guide to understanding the pros and cons of each type:
A DWR coated face fabric laminated to a micro-porous membrane backer with a separate fabric or mesh liner. The DWR coated shell works alongside the membrane backer to prevent water moisture from penetrating while the inner liner gives you next-to-skin comfort. The downside is that the liner adds weight and bulk as well as placing another layer for water vapour to pass through before escaping through the membrane. Great for everyday rain protection where durability isn’t an issue.
Click this link to view all of our 2-Layer garments.
A DWR coated face fabric laminated to a micro-porous membrane backer with a printed or sprayed on partial protective layer (in place of a separate fabric liner) to guard the waterproof membrane against becoming clogged with dirt and grease. This provides the wearer with a lightweight and highly packable design and forms the standard waterproof construction for everyday use with a great level of waterproof-breathable protection. The downside is that the added layer reduces the membrane’s breathability and can decrease durability due to the lack of a separate fabric liner.
Click this link to view all of our 2.5-Layer garments.
DWR coated face and membrane but with a lightweight fabric laminated on the back side of the micro-porous membrane. This offers the highest performance and most durable construction of the three, making it ideal for mountaineers and outdoors enthusiasts traversing challenging terrain. Downsides are a slight reduction in comfort and flexibility in the fabric. The added level of construction also gives 3-layer garments a higher price point.
Click this link to view all of our 3-Layer garments.
DWR – Durable Water Repellent: This is a polymer applied to face fabrics that is absorbed into the fibres and causes water to bead and roll off on contact. It provides an initial barrier to rain moisture and works alongside the breathable membrane to prevent water from getting in. DWR coatings can wear off with repeated wear leaving the membrane to do all the work. While a good quality membrane will continue to prevent water from penetrating, the lack of an effective DWR means the fibres can become waterlogged and clogged with dirt and oils. This greatly reduces the membrane’s ability to breathe which leads to the build-up of condensation which can leave you damp on the inside.
Use our Buying Guide Index to explore tonnes of useful information about equipment, clothing, footwear and more. These guides are not just for climbing and snowboarding - all of our sports are covered.
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