waterproofbreathable

Waterproof breathable, sometimes written as waterproof-breathable, refers to fabrics and membranes engineered to block liquid water from penetrating the garment while allowing body-generated moisture to escape as vapor. This combination aims to keep the wearer dry from rain and snow on the outside while reducing interior dampness from perspiration. It is a common feature in rain jackets, hardshells, and other outdoor apparel, as well as in some protective coverings for gear.

Most waterproof breathable systems rely on a waterproof barrier laminated to a flexible fabric. The barrier is typically a microporous membrane or a non-porous hydrophilic film. Membranes based on ePTFE (as used in Gore-Tex), polyurethane films (PU), or similar polymers are common. Breathability is quantified by moisture vapor transmission rate (MVTR), while water resistance is described by hydrostatic head (water column). Some brands use non-porous systems, such as Sympatex, which transport moisture by diffusion and wicking rather than pores.

Construction often includes taped seams to prevent water ingress at joints, and a durable outer shell treatment, such as a DWR coating. The overall performance depends on layering, fit, activity level, and the conditions ambient temperature and humidity. Care instructions typically include washing and reproofing to maintain both breathability and water repellency. Real-world breathability can decrease when the membrane is wet or compressed by movement or layering.

Limitations and considerations: Waterproof breathable fabrics are not the same as fully waterproof fabrics; they have finite breathability and can become less effective in prolonged exposure to heavy rain or high humidity. They tend to be more expensive and may require maintenance, such as reproofing and regular seam sealing, to maintain performance.