Waterproof and Breathability Rating

What is a waterproof rating?  What does this actually mean?

The pieces that Loki has with waterproof ratings fall within these three levels:

8,000mm - Rainproof and Waterproof under light pressure (Light rain, average snow, light pressure.)

• Mountain Hoodie Extreme (8,000mm/5,000 g/m²)

10,000mm - Rainproof and Waterproof under light pressure (Light rain, average snow, light pressure.)

• Meta Snowsport Jacket
• Valhalla 2-Layer Shell
• Valhalla Pants
• Massif Parka
• All In One Light Shell

15,000mm - Rainproof and Waterproof except under high pressure (Moderate rain, average snow, light pressure.)

• Alpine Shell
• Alpine Pants

     Manufacturers typically describe the waterproof breathability of fabrics using two numbers. The first is in millimeters (mm) and is a measure of how waterproof a fabric is. In the case of a 10k or 10,000 mm fabric, if you put a square tube with inner dimensions of 1” x 1” over a piece of said fabric, you could fill it with water to a height of 10,000 mm (32.8 feet) before water would begin to leak through. The higher the number, the more waterproof the fabric.

     The second number is a measure of how breathable the fabric is, and is normally expressed in terms of how many grams (g) of water vapor can pass through a square meter (m²) of the fabric from the inside to the outside in a 24 hour period. In the case of a 20k (20,000 g) fabric, this would be 20,000 grams. The larger the number, the more breathable the fabric.