HSE Pendulum Test Values — what the numbers actually mean.

The three PTV bands

The UK Health and Safety Executive, working with the UK Slip Resistance Group, classifies pedestrian slip risk on the basis of Pendulum Test Value (PTV) into three bands. The classification is now embedded in BS 7976, BS EN 16165, and the UKSRG Guidelines Issue 5 (2016).

Where the 1-in-1,000,000 figure comes from

You will frequently see the claim that a PTV of 36 corresponds to a slip risk of approximately 1 in 1,000,000. The figure comes from HSE-commissioned research correlating pendulum results to actual recorded slip incidents across a large dataset of UK floors. The headline correlations are:

• PTV 19 — approximately 1 in 2 risk of slipping
• PTV 24 — approximately 1 in 20
• PTV 27 — approximately 1 in 200
• PTV 29 — approximately 1 in 10,000
• PTV 34 — approximately 1 in 100,000
• PTV 36 — approximately 1 in 1,000,000

The non-linearity is striking: the difference between PTV 24 and PTV 36 is 12 numerical points but five orders of magnitude in slip risk. This is why the HSE has set the "low slip potential" threshold where it has, and why a floor measuring PTV 35 — only one point below the threshold — is materially less safe than its score might suggest.

Wet versus dry — which one matters?

Almost every floor scores acceptably when measured dry. Slip incidents almost always involve some form of contamination — water, food residue, oil, ice, soap, leaves. The HSE thresholds are therefore applied to wet PTV readings, not dry. A pendulum test report that quotes only dry values is, for risk management purposes, largely uninformative.

That said, dry readings are diagnostically useful: a large differential between dry and wet PTV indicates a surface highly sensitive to contamination, where management of cleaning and spillage becomes critical.

Slider selection — Four-S vs TRL

The pendulum can be used with two standard rubber sliders:

• Slider 96 (Four-S) — used for shod pedestrian assessments. This is the default for almost all UK commercial and public floors.
• Slider 55 (TRL) — used for barefoot environments such as swimming pool surrounds, changing rooms, and shower areas.

The thresholds above apply to Slider 96. Barefoot environments using Slider 55 have their own threshold structure, generally requiring higher absolute PTV values for equivalent risk.

The dry-only "above 36" trap

Specifying floors — PTV vs R-rating

Flooring manufacturers commonly publish R-ratings (DIN 51130 ramp test) for their products. R-ratings are useful comparative data but they are not recognised by the HSE for in-situ assessment, for two reasons: they are laboratory measurements on pristine new product, and the test setup does not match real-world contamination scenarios.

Approximate correlations between R-rating and PTV (always treat these as indicative only):

• R9 — typically PTV 15–20 (high slip potential when wet)
• R10 — typically PTV 20–30
• R11 — typically PTV 30–40
• R12 — typically PTV 40–50
• R13 — typically PTV 50+

Best practice when specifying flooring: ask for both the R-rating and a manufacturer-supplied pendulum test certificate, ideally with a PTV measurement on a representative installed sample.

What to do with a "high slip potential" result

A PTV reading below 25 is an immediate risk management priority. Practical responses:

• Short term: Contamination control (cleaning frequency, drying, signage), routing changes
• Medium term: Anti-slip treatment, mechanical surface modification, slip-resistant coatings
• Long term: Floor replacement with a specified PTV target on installation

We don't sell remediation products or services. That means our advice on treatment options is genuinely independent — we'll point you towards the right approach for your specific floor and contamination profile, and we have no commercial interest in any one solution.