Reference

Waterproof Jacket Glossary

Short, consistent definitions of the technical terms used across this site. Each definition links to the sourced article that explains it in depth; figures and test conditions live there, not here.

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Ratings & testing

Hydrostatic headalso: HH, water column, mm rating: A laboratory measurement of how much water pressure a fabric withstands before water is forced through, expressed in millimetres of water column. It describes a fabric sample under a named test method, not the finished jacket in real rain.; Hydrostatic head explained Waterproof ratings explained
Waterproof rating: Any published figure describing resistance to water penetration. Figures are only comparable when the test method is the same; several manufacturers publish no figure at all.; Waterproof ratings explained What does 20,000 mm waterproof mean?Is 10,000 mm waterproof enough?
ISO 811: The international standard method for determining a textile's resistance to water penetration by hydrostatic pressure.; Hydrostatic head explained
JIS L 1092: The Japanese Industrial Standard for testing water resistance of textiles, frequently cited by Asian fabric mills and some brands. Its results are not directly interchangeable with other methods.; Hydrostatic head explained
EN 343: The former European standard for protective clothing against rain, which classified garments for water penetration and water-vapour resistance. It has been withdrawn and replaced by EN ISO 24232; older garments may still cite it.; Waterproof ratings explained
EN ISO 24232: The current standard for protective clothing against rain that replaced EN 343 in Europe.; Waterproof ratings explained

Breathability

Breathability: The ability of a fabric to let water vapour from the body escape. It is measured in several incompatible ways, depends strongly on conditions, and cannot be reduced to one universal number.; Breathability explained
MVTRalso: moisture vapour transmission rate, g/m²/24h: Moisture vapour transmission rate: grams of water vapour passing through a square metre of fabric in 24 hours. Higher is more breathable, but results vary greatly by method, so figures from different tests cannot be compared.; MVTR explained
RETalso: resistance to evaporative heat transfer: Resistance to evaporative heat transfer, measured on a sweating hot plate (ISO 11092). Lower is more breathable. RET cannot be converted to MVTR.; RET explained
Air permeability: How much air passes through a fabric under a set pressure difference. Most waterproof membranes are close to air-impermeable; a few platforms, such as Polartec NeoShell, publish a measurable airflow.; Breathability explained Polartec NeoShell

Construction

Membrane: A thin film bonded to the face fabric that blocks liquid water while allowing some water vapour through. Common bases include ePTFE, polyurethane and polyester.; What is a waterproof membrane?Technology database
ePTFEalso: expanded PTFE: Expanded polytetrafluoroethylene, the microporous membrane material used in classic GORE-TEX and eVent fabrics.; What is a waterproof membrane?GORE-TEX
ePEalso: expanded polyethylene: Expanded polyethylene, the PFC-free membrane material Gore introduced to replace ePTFE in much of its consumer range.; GORE-TEX ePE
Coatingalso: PU coating: A waterproof layer applied in liquid form to the inside of a fabric, rather than laminated as a separate film. Common in 2-layer and 2.5-layer jackets.; What is a waterproof membrane?
Microporous vs hydrophilic: Two ways a barrier passes water vapour: microporous films have pores far smaller than water droplets; hydrophilic (monolithic) films have no pores and move vapour by diffusion through the material.; What is a waterproof membrane?
2-layer (2L): A face fabric bonded to a membrane or coating, with a separate hanging liner protecting the inside.; 2-layer vs 2.5-layer vs 3-layer
2.5-layer (2.5L): A face fabric and membrane or coating protected on the inside by a printed or sprayed half-layer instead of a full fabric backer.; 2-layer vs 2.5-layer vs 3-layer
3-layer (3L): Face fabric, membrane and a thin backer fabric laminated into one material. Layer count describes how the fabric is assembled, not how well it performs.; 2-layer vs 2.5-layer vs 3-layer
Face fabric: The outer textile of a waterproof jacket. It carries the DWR finish and takes the abrasion; its thickness is often given in denier.; What is a waterproof membrane?
Denier (D): A measure of yarn mass (grams per 9,000 metres). It indicates yarn thickness, not overall fabric durability on its own.; Jacket database
Seam tapingalso: seam sealing: Waterproof tape bonded over stitched seams to seal the needle holes. Without it a jacket leaks at the seams regardless of its fabric rating.; Waterproof vs water-resistant

Treatments & chemistry

DWRalso: durable water repellent: A finish on the face fabric that makes water bead and roll off. It wears with use and can be renewed. It is separate from the waterproof membrane.; What is DWR?
Wetting out: When the face fabric becomes saturated because the DWR has stopped working. The jacket usually still blocks water, but breathability drops and it can feel wet inside.; What is DWR?
PFASalso: PFC, per- and polyfluoroalkyl substances: A large group of fluorinated chemicals historically used in DWR finishes and some membranes. “PFC-free” and “PFAS-free” are not interchangeable claims; check which part of the garment a claim covers.; What is DWR?

Features

Water-resistantalso: water-repellent: Resists light or brief rain, usually through a DWR finish, but lacks a sealed waterproof barrier and taped seams.; Waterproof vs water-resistant
Pit zips: Underarm zips that open for mechanical ventilation, moving far more air than a membrane can.; Jacket database
Storm flap: A fabric flap covering the main zip to keep driven rain out where the zip itself is not waterproof.; Waterproof vs water-resistant
Helmet-compatible hood: A hood the manufacturer states is cut to fit over a climbing or cycling helmet. Only shown in our database where published.; Jacket database