Quick answer: In the UK, safety boots are certified to EN ISO 20345. The sole decides three things: whether a nail can puncture through (the midsole, marked "P"), how well you grip (the outsole, rated SRA, SRB or SRC), and how it copes with heat, oil and cold (HRO, FO, CI). Under UK law, employers must provide suitable PPE free of charge where the risk assessment calls for it.
New to the S-codes? Start with our steel toe cap boots and safety boots buying guide, then come back here for the detail on soles.
The two parts of a safety sole
Outsole (the part that meets the ground)
- PU (polyurethane): light and cushioned, with good oil and abrasion resistance. Suits general site, warehouse and farm work.
- Rubber / nitrile rubber: better grip and heat resistance (HRO, tested to 300°C contact heat). Suits hot surfaces, wet ground and heavy-duty use.
- Cleated (deep lug) tread: required for S3. Grips mud and uneven ground, but can hold debris indoors.
Midsole (inside the sole, for puncture protection, the "P" rating)
| Type | Pros | Cons |
|---|---|---|
| Steel plate | Tough, lower cost | Heavier, conducts cold, can set off metal detectors, doesn't cover the whole sole |
| Textile / composite (Kevlar-type) | Lighter, more flexible, full-foot coverage | Usually a little more expensive |
Both types must pass the 1,100N penetration test to earn the P rating.
Sole-related codes at a glance
| Code | What it means |
|---|---|
| P | Midsole puncture resistance (S1P, S3) |
| A / E | Antistatic sole / heel energy absorption (S1 and above) |
| SRA | Grip on ceramic tile with soap solution |
| SRB | Grip on steel with glycerol |
| SRC | Passes both SRA and SRB (best slip resistance) |
| HRO | Heat-resistant outsole |
| FO | Fuel and oil resistant sole |
| CI | Cold-insulated sole |
Which to choose: S1P suits dry indoor work. S3 suits outdoor, wet and construction work, because it adds a water-resistant upper and a cleated sole.
Certification: what the markings mean
- Boots carry a CE or UKCA mark plus EN ISO 20345 on the label (the current edition is 2022).
- Every safety toe cap is tested to 200 joules impact and 15kN compression.
- Check the inside label for the full code set. A product name such as "S3 style" is not proof of certification.
- Unmarked or counterfeit boots are not certified, however they look.
UK law: who has to do what
- Employers must assess the risks, and where those risks cannot be adequately controlled in other ways, supply suitable PPE free of charge (Personal Protective Equipment at Work Regulations 1992; Health and Safety at Work etc. Act 1974). Safety footwear counts as PPE.
- Casual and agency workers: since 6 April 2022, the duty also covers "limb (b)" workers, who previously often had to buy their own (Personal Protective Equipment at Work Regulations 2022).
- Workers must wear and look after the PPE provided, check it before use and report any loss or defect.
- Sellers must only supply PPE that meets UK requirements (Personal Protective Equipment Regulations 2002).
- No law names one rating for every job. The risk assessment decides it (for example, nail hazards mean you need P, and wet sites point to S3).
- Replace boots when the sole is cracked or worn smooth, the toe cap is exposed, or the midsole is damaged.
This is general guidance, not legal advice. Check current HSE guidance for your workplace.
Frequently asked questions
Is S3 always better than S1P?
No. It is different protection: water resistance and a cleated sole. For dry indoor work, S1P can be the better fit.
Steel or composite midsole?
Composite is lighter and covers the whole sole. Steel is cheaper and very tough.
What does SRC mean on a safety boot?
The sole passed both the ceramic tile (SRA) and steel (SRB) slip tests.
Do I have to buy my own safety boots?
Generally no, if your employer requires them. They must provide suitable PPE free of charge.
Do safety boots expire?
There is no fixed legal date, but check for wear and follow the manufacturer's guidance.
