Order Tracking  |  FAQ  |  Size & Fit Charts

Rainwear Defined

Rainwear Defined

  • 07 June 2019
  • |
  • First Ascent

Don’t hide from the rain this winter, instead purchase a rain jacket designed to keep you dry and protected when the clouds open up.

First Ascent - Rainwear Defined


Selecting the right waterproof jacket for the type of activity is essential, however having an understanding of the terms relating to waterproofness is imperative when scouting for a jacket.


Waterproof jackets offer the best performance in wet conditions. Designed with an outer shell impervious to water, these jackets feature fully taped seams and a durable water repellent (DWR) outer coating, to keep water from moving through the jackets surface, while still allowing perspiration to move out.


These jackets are hydrophobic meaning that they are able to bead water off the jackets surface, keeping the inner dry during light moisture or rain conditions, but do not provide full waterproof coverage.

Water-repellent jackets are designed using special techniques, materials and fabrics, which are able to repel water away from the jackets surface. Water-repellent garments have a waterproof membrane, combined with a Durable Water Repellent (DWR) coating, but are not tape sealed.


In theory if a jacket is water-resistant, it has been designed to have resistance against small amounts of water for a brief time.

These jackets are typically coated with a light coating of DWR, which gives the garment a protective layer and assists in increasing the endurance of the jacket when exposed to moisture or light drizzle conditions. Water-resistant jackets are generally lightweight and are also breathable.

First Ascent - Rainwear Defined


The waterproof level of a garment is determined using a water column rating scale.


Water column rating is a measurement scale used to measure the waterproofness of a garments fabric. The water column of First Ascent fabric is measured in millimetres and ranges from 2,000mm to 20,000mm; this measurement is an indication of the type of rain conditions, which the jacket is able to withstand. 

First Ascent - Rainwear Defined


The water column rating of a garment is tested through placing a glass tube over the surface of the fabric and measuring how much water (measured in millimetres) the jacket can hold, before it penetrates through the fabric. This test is conducted by an independent laboratory or in-house.

2000 - 5000mm No resistance to some resistance to small amounts of moisture Drizzle/Snow
5000 - 8000mm Waterproof under drizzle or light pressure Light to average rain
10000 - 15000mm Waterproof under light to moderate pressure Moderate rain
20000mm Waterproof under high pressure Heavy rain


It is as important for a waterproof jacket to keep water out, as it is for perspiration to escape, especially when being active. If sweat is unable to escape, moisture will build-up in the jacket, resulting in the wearer feeling damp or wet. 

Breathability is measured by how much water vapour can be transferred (MVT) through a square meter of fabric in a 24-hour period. The higher the number indicated the more breathable the jacket or fabric will be. Breathability is measured in gr/m2/day

<5000gr/m2/day Low 
>5000gr/m2/day Moderate 
>20000gr/m2/day High


Waterproof jackets are built using different membrane constructions; these constructions feature either a 3-layer, 2.5-layer, 2-layer or a PU coating.

First Ascent - Rainwear Defined


Jackets that a feature 3-layer membranes offer the best protection against rain. These jackets contain a DWR face fabric and laminated membrane, boned to a fine mesh/scrim inner surface. These layers are all bonded together to create one strong layer. Example: Men's Vapourstretch Rain Jacket


Jackets with a 2.5 layer membrane have an abbreviated pattern on the inner surface, which has been screened onto the inside of the jacket. Garments, which feature a 2.5-layer membrane, are considered to be lightweight rain garments, best-used in active wear jacket. Example: Submerge Rain Jacket,  AR-X Waterproof Jacket and X-Trail Running Jacket


Jackets with a 2-layer membrane combine a waterproof outer shell and an inner lining layer of mesh or polyester fabric, sometimes both. An inner lining is added to a jacket as barrier between the waterproof outer. This inner layer is designed to protect the outer, preventing deterioration of the jacket from the continuous movements by the wearer. Example: Discovery 3-in-1 Jacket and Men's Flash Flood Pants

3-in-1 Jackets

These jackets are versatile and suitable for all year round wear. Featuring a waterproof outer, with a detachable fleece inner, these jackets can be interconnected into all other garments which bear an interconnect mark. Example: Discovery 3-in-1 Jacket

First Ascent - Rainwear Defined


Durable Water Repellent (DWR) is a coating that is adhered to almost all First Ascent outerwear garments and assists with preventing a garment from becoming saturated by moisture or water, by beading water off the jackets surface.

A DWR coating has a lifespan and is affected by increased use, abrasions and dirt, and will wear off over time. Nikwax Tech Wash is used to treat jackets with a DWR coating, increasing the lifespan of the jacket.



Seam-sealed, refers to the covering of the tiny holes made in the garment during the sewing process, such as by the zip, hem etc. Fully-tape sealed garments have been sealed by a waterproof tape overlay, to prevent water leakage into the jacket. All First Ascent rainwear labelled as waterproof are fully seam sealed.


Rainwear jackets have a tendency to feature many zips, from a full front zip to pockets and pit zips. To ensure that water does not penetrate through the zipper, all zip systems feature a water-resistant zip or a storm flap. Storm flaps either have a single or double layer.


The hood of rainwear jacket, features a built-in visor and volume control capabilities, this allows the hood to be adjusted and fine-tuned, to how big you want the size of the opening.

First Ascent - Rainwear Defined


Majority of hiking specific, rainwear jackets, have pockets situated just above the hip belt and away from the shoulder straps, this design allows for easy access to pockets while wearing a pack. Pocket zips can also double up as extra ventilation, such as in the Submerge Rain Jacket. First Ascent running and cycling jackets have pockets positioned lower on the garment, for easy access to race nutrition.


Even the most breathable rain jackets, can have a perspiration build-up inside during strenuous activity. Incorporating pit zips or underarm vents into the design, allows for further breathability and air movement. As per the Men's Vapourstretch Rain Jacket and the Ladies X-Trail Running Jacket


First Ascent rainwear jackets, which fall into the activewear category, feature packable properties for easy storage when not in use. These jackets are designed to pack into their pocket for convenience while on-the-go. Example: Diverge Waterproof Cycling Jacket, AR-X Waterproof JacketSubmerge Rain Jacket and  X-Trail Running Jacket


First Ascent Vapourtex Fabric

The First Ascent Vapoutex technology represents a high-performance and innovative fabric which offers superior waterproof protection.

All garments bearing the Vapourtex mark feature an outer impervious to water, a seam sealed inner and a minimum spec of 2000m WP/ 3000mm BR.
The durable First Ascent Vapourtex range will keep you dry in wet conditions, while allowing perspiration to pass to the outer surface, providing ultimate comfort during all expeditions.

View our Rainwear Range

First Ascent - Rainwear Defined