Waterproof Buying Guide

Everything you need to know when shopping for Waterproof Clothing

Thanks to modern technology, staying dry is pretty manageable if you choose the right level of protection for the conditions.

Choosing the right Waterproof Jacket or Waterproof Trousers can often feel overwhelming for many people due to the complexity and diversity of options available. Knowing the main features and benefits of the different fabrics options is the first step in choosing the right garment for your next adventure. 

Each type of fabric listed below is both waterproof and breathable in varying degrees, but choosing the right waterproof clothing for you also depends on other factors, such as; the brand, the fit, the pockets, the hood, even the colour!

This guide is for those curious about what actually makes a garment waterproof and if you want to learn more about waterproof and breathability ratings. 

First we will break down all the terminology and explain exactly what “waterproof” really means. 

What does 'Waterproof' mean?

Waterproof Portwest Clothing

Fabric that is “100% waterproof” doesn’t really exist. With enough pressure, water will eventually pass through any fabric. Technically all fabrics are water-resistant to some degree but to be categorized as waterproof, a material must provide a higher level of sustained water resistance.

A waterproof fabric is accomplished by combining fabric with special waterproof membranes or coatings which enables the fabrics to become impervious to water, under pressure to a certain degree. When a product is labelled as waterproof, it must either be made of a waterproof material or include a waterproof breathable membrane (or a waterproof breathable laminate). Products that have only a DWR (durable water repellent) coating are not considered waterproof.

Membrane: This is a layer of waterproof material. Membranes are usually made of ePTFE or polyurethanem which is either bonded to the outer layer of the jacket or suspended between two fabric layers.

DWRThis is the substance applied to the exterior of the face fabric. It causes water to bead up and fall off rather than absorb. A high-quality DWR keeps the face fabric from wetting out and maintains breathability. Worn-out or low-quality DWR coatings are the primary reason that waterproof garments fail. A “wetted out” waterproof garment cannot breathe. 

How much pressure a fabric can endure before water starts to leak through is used to “rate” how waterproof the fabric is.

Waterproof Rating

A fabric’s waterproof rating is directly related to its ability to withstand water under pressure in a controlled, laboratory setting. The more resistance to pressurized water equates to a higher waterproof rating. The higher a garment's waterproof rating, the longer the fabric will remain waterproof for.

Rating Resistance Weather
 0 – 1,500mm Water resistant / Snowproof Very light rain
 1,500mm – 5,000mm Waterproof Light to average rain
 5,000mm Very Waterproof Moderate to heavy rain
 10,000mm - 20,000mm + Highly Waterproof Heavy rain

💧 1500mm to 2000mm / 1.5k - 2k

Jackets with a rating of 1,500mm to 2,000mm are suitable for everyday use, whether it be around town or walking the dog. These jackets may also be suitable for walkers or hikers who aren’t likely to get caught out in heavy, sustained rain.

💧 5000mm to 10,000mm / 5k - 10k

A rating of 5000mm to 10,000mm is suitable for just about all weather conditions but equally suitable for walking the dog or taking a serious trek in bad conditions. These higher rated jackets will also be breathable.

💧 10,00mm to 20.000mm / 10k - 20k+

    A Gore-Tex® fabric can withstand about 40,000mm of water pressure. This higher rating can become necessary if you’re kneeling on snow or carrying a heavy pack in the rain, which puts additional pressure on the fabric.

    A "mm/24 hours" rating refers to the amount of rainfall a fabric can withstand in a single day. A 10,000mm waterproof rating means the garment can withstand 10,000mm of rainfall in a single day without letting moisture in. The higher the number, the more waterproof the item will be. Gore-Tex®, for example, has a waterproof rating of 28,000mm.

    So what does this mean for me?

    What it evolves around is breathability - which is a fabric's ability to let air pass through so that sweat can evaporate. The aim is to create a garment which can maintain a comfortable internal micro-climate while protecting you during wet weather activities.

    Some fabrics such as GORE-TEX Pro, give waterproof and breathable protection in the harshest conditions, while others such as GORE-TEX Active, provide highly breathable and waterproof performance, perfect for those moving fast and light. 

    VENTRON is Portwest's own waterproof, breathable membrane.

    All types of jackets listed in our rain jacket section provide both waterproof and breathable to varying degrees, but choosing the right waterproof clothing for you also depends on many other factors; the brand, the fit, the pockets, the hood, the colour!

    Knowing the main features and benefits of each different fabric is just the first step in choosing the right garment for your intended activity.

    More than just the Fabric

    A jacket can be treated with a waterproof coating and have a waterproof membrane but not be fully waterproof. For a jacket to be as close to 100% waterproof as possible, it will also need to have taped seams. Taped seams are heat-sealed seams that stop water from coming through the stitching. It is particularly important that you choose a jacket with taped seams if you will be in heavy, prolonged rain.

    With your new knowledge of waterproof fabrics, you are now ready to go shopping and get geared up for your next adventure!

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