Buying safety footwear used to mean choosing between S1P and S3. The 2022 edition of EN ISO 20345 changed more than most buyers realise: two new waterproof classes, a new way of marking puncture protection, new slip-resistance markings, and fuel-oil resistance moving from mandatory to optional. Because boots certified to the 2011 version can still be sold, you will see both sets of markings side by side for several years. This guide explains both.
What every safety boot must do
EN ISO 20345 covers footwear with a protective toecap. Whatever the class, the toecap must withstand a 200-joule impact and a 15-kilonewton compression test, and under the 2022 edition every class must also pass a basic slip-resistance test on a ceramic tile with a detergent solution.
The classes, SB to S7
| Class | Builds on | Adds | Typical use |
|---|---|---|---|
| SB | — | 200 J toecap, basic slip resistance | Specialist footwear; rarely bought as a general boot |
| S1 | SB | Closed heel, antistatic, energy-absorbing heel | Dry indoor work: warehouses, factories |
| S1P | S1 | Puncture-resistant midsole (S1PS or S1PL if non-metallic); no water resistance | Dry indoor sites with a nail or debris risk: logistics, fit-out |
| S2 | S1 | Water-resistant upper (resists water penetration and absorption) | Indoor work with occasional splashes |
| S3 | S2 | Puncture-resistant midsole, cleated outsole | Construction and outdoor sites |
| S4 | SB | All-polymer (rubber or PVC) wellington construction, antistatic, energy absorption | Wet, washdown and food environments |
| S5 | S4 | Puncture-resistant midsole, cleated outsole | Wet sites with nail or debris risk |
| S6 | S2 | Whole-footwear water resistance (WR) | Wet conditions without a puncture risk |
| S7 | S3 | Whole-footwear water resistance (WR) | Wet outdoor sites with a puncture risk |
The difference between S3 and S7 matters on wet UK sites. An S3 boot has a water-resistant upper, but water can still get in through the seams and tongue; S7 is tested as a whole boot. Many boots are now built to S7S — fully water-resistant with non-metallic puncture protection — including models in the Titan safety footwear range we stock.
What changed from the 2011 version
| Topic | 2011 edition | 2022 edition |
|---|---|---|
| Waterproof classes | None — WR was an optional extra | New S6 (S2 + WR) and S7 (S3 + WR) |
| Puncture protection | P (tested with a 4.5 mm nail) | P for metal inserts; PL for non-metallic tested with a 4.5 mm nail; PS for non-metallic tested with a 3.0 mm nail |
| Slip resistance | SRA (tile + detergent), SRB (steel + glycerine), SRC (both) | Basic tile + detergent test is mandatory; SR marks the additional tile + glycerine test |
| Fuel-oil resistance | Mandatory for every class except SB | Optional, marked FO |
| New optional markings | — | LG (ladder grip), SC (scuff cap) |
Because a smaller nail concentrates more pressure, PS offers a higher level of non-metallic puncture protection than PL. So "S3S" on a 2022 boot tells you more than "S3" did on a 2011 boot. Manufacturers expect both editions to be on sale until around November 2029, so check which standard is printed on the tongue label before comparing two boots.
The extra markings worth knowing
| Marking | Meaning |
|---|---|
| WR | Whole footwear water resistance |
| WPA | Upper resists water penetration and absorption |
| FO | Outsole resistant to fuel oil (optional since 2022) |
| SR | Passed the additional slip test on ceramic tile with glycerine |
| HRO | Heat-resistant outsole (tested at 300 °C) |
| CI / HI | Insulation against cold / heat |
| M | Metatarsal protection |
| AN | Ankle protection |
| CR | Cut-resistant upper |
| LG / SC | Ladder grip / scuff cap |
ESD (electrostatic discharge) is not part of EN ISO 20345. ESD footwear is tested separately to IEC 61340 for electronics and other static-sensitive work, and is marked in addition to the safety class.
How to choose
- Dry indoor floors — warehouses, workshops, logistics: S1 or S1P, often a lighter safety trainer or safety shoe.
- Outdoor sites with nails, rebar and debris: S3 minimum; S7 if people are standing in wet ground all day — see our safety boots.
- Standing water, washdown, farms and food processing: S4 or S5 safety wellingtons.
- Ladders and scaffolds: look for LG. Oils and fuel on the floor: look for FO, which is no longer automatic.
- Kneeling or heavy crawling work: SC protects the toe from wearing through.
Then consider fit, weight and comfort. The best-rated boot on the market does nothing if it sits in a locker because it rubs — trial a pair on your own site before rolling a model out to a whole team.
General guidance only — always match footwear to your site's own risk assessment.
Frequently asked questions
- What is the difference between S3 and S7 safety boots?
- Both have a toecap, antistatic properties, energy absorption, a water-resistant upper, puncture protection and a cleated sole. S7 adds whole-footwear water resistance (WR), tested on the complete boot rather than just the upper.
- What does S3S or S7L mean?
- The last letter shows the puncture protection under EN ISO 20345:2022. S means a non-metallic insert tested with a 3.0 mm nail; L means a non-metallic insert tested with a 4.5 mm nail. PS is the higher of the two.
- What happened to SRC slip resistance?
- The 2022 edition removed SRA, SRB and SRC. A slip test on ceramic tile with detergent is now mandatory for every class, and boots that also pass a tile test with glycerine are marked SR.
- Are boots certified to EN ISO 20345:2011 still legal to buy?
- Yes. Footwear certified to the 2011 edition can be sold while its certification remains valid, and manufacturers expect both editions to be on sale until around November 2029. Compare boots on the edition printed on the label.
- Do safety boots still have to be fuel-oil resistant?
- Not under the 2022 edition. Fuel-oil resistance is now an optional test marked FO, so if oil or fuel is present on your floors, check for the FO marking specifically.