Standard explainer · EN 343
"Waterproof" on a work jacket is a certified claim with two numbers behind it: how hard the fabric resists rain getting in, and how well it lets sweat get out. Most buying mistakes come from reading only the first one.
The two numbers
EN 343 rates protective clothing against rain with two classes, shown together on the garment pictogram:
The second number is where comfort lives. A worker generating heat inside a non-breathable shell gets wet from their own sweat as surely as from rain — colder, clammier and slower to dry. That's the 4:1 trap: maximum penetration resistance, minimum breathability, miserable by mid-morning if the work is physical.
Choosing
Pick both numbers to the work, not just the rain.
| Work pattern | Sensible spec | Why |
|---|---|---|
| Occasional showers, mostly sheltered | 2:2 and up | Everyday site cover without shell prices |
| Outdoor trades, full shifts in weather | 3:3 | The workhorse spec — real rain, real effort |
| Static roles in driving rain (traffic, security, plant) | 4 : 2+ | Low exertion tolerates lower breathability; penetration matters most |
| High-output work in rain (groundworks, rail) | 3–4 : 3–4 | Breathability stops the inside-out soaking |
Keeping it rated
The certified performance assumes the garment's DWR coating is alive and its seams intact. When rain stops beading and the face fabric wets out, breathability collapses and the jacket "leaks" without leaking — the fix is cleaning and reproofing, covered step-by-step in reproofing waterproofs.
On hi-vis waterproofs, remember the garment is certified twice over — the rain rating and EN ISO 20471 visibility — and each wash counts against the hi-vis wash limit. Buy once, maintain deliberately.
Label literacy
Questions
Two classes, each 1–4: the first is resistance to water penetration (how hard rain is kept out), the second is water vapour resistance (breathability — how easily sweat escapes). Higher is better in both; the current revision added class 4 penetration, tested after simulated wear.
Only if the breathability class is healthy too. A 4:1 garment keeps rain out and sweat in — fine for static roles, miserable for physical work. For high-output outdoor trades, aim for 3 or 4 in both positions.
Usually it's wetting out, not leaking: the DWR coating has worn off, the face fabric soaks up water, and breathability collapses — so sweat condenses inside. Washing the jacket clean and applying a wash-in reproofer restores it; genuine leaks track to seams or damage.
No — EN 343 covers rain only. Cold protection is a separate standard (EN 342 for below −5 °C environments), which is why winter site jackets are often certified to both, or worn as a shell over insulating layers.
EN 343 waterproofs, EN 342 cold-store kit and hi-vis winter jackets from stock — embroidered before dispatch.