Published 2026-03-11 · Slip-Tests UK
Why wet barefoot environments need a different test
The standard pendulum test (BS 7976 / BS EN 16165) uses a rubber slider that simulates the heel of a commercial shoe striking a floor. This is appropriate for commercial floors where users are shod. It is not appropriate for swimming pool surrounds, changing-room floors, or shower trays where users are barefoot and the surface is deliberately wet.
The skin of a bare foot has very different friction characteristics from a shoe sole. A surface can perform acceptably in shod pendulum testing and perform poorly when tested wet-barefoot — or vice versa. Specialist wet-barefoot testing is essential for any environment where these conditions apply.
What DIN 51097 measures
DIN 51097 is a German standard for laboratory ramp testing of flooring in wet barefoot conditions. A test technician walks barefoot up an inclined platform holding a flooring sample, wetted with soapy water. The angle at which the technician begins to slip determines the classification.
The standard produces three classifications:
- Class A — minimum wet-barefoot slip resistance. Safe angle ≥ 12°.
- Class B — moderate wet-barefoot slip resistance. Safe angle ≥ 18°.
- Class C — high wet-barefoot slip resistance. Safe angle ≥ 24°.
Which class applies where?
Class A — domestic and low-risk
Class A products are commonly specified for domestic bathrooms, shower trays, and general wet areas where the risk profile is low. They are rarely acceptable for commercial or public-use environments.
Class B — commercial wet areas
Class B is the typical specification for commercial shower rooms, changing rooms, communal wet areas, and most commercial bathroom environments. It balances acceptable slip resistance with sufficient cleanability and comfort underfoot.
Class C — pool surrounds and high-risk wet areas
Class C is the expected specification for swimming pool surrounds, spa wet areas, water park walkways, and any environment where barefoot users are exposed to persistent wet conditions with elevated slip consequence. Many stone and tile products marketed for pool use fail to achieve Class C on independent testing — specification without verification is a recurring source of commercial claims.
How DIN 51097 relates to pendulum testing
DIN 51097 and BS 7976 / BS EN 16165 pendulum testing are complementary, not alternative. A wet area in a commercial pool changing room might reasonably be tested to both — DIN 51097 for the wet-barefoot pool surround, pendulum testing for the shod approach corridor and communal wet-shod zones.
For a UK hotel spa specification, the typical brief might include: DIN 51097 Class C for pool decks, DIN 51097 Class B for shower room floors, and BS 7976 / BS EN 16165 pendulum testing for the corridor approaches.
UK accreditation and UKAS
DIN 51097 is within the scope of UKAS ISO 17025 accreditation for laboratories that hold it explicitly in their Schedule of Accreditation. Surface Performance's Schedule No. 7933 covers DIN 51097 alongside BS 7976 / BS EN 16165, allowing integrated laboratory testing of products for any UK commercial wet-barefoot environment.
Common mistakes UK specifiers make
Mistake 1: specifying only R-ratings
R-ratings (DIN 51130) are for shod environments. A Class A/B/C DIN 51097 rating is the correct barefoot wet specification. Specifying "R11" for a pool surround is not meaningful — the two standards measure different things under different conditions.
Mistake 2: accepting manufacturer claims without verification
Products marketed as "pool safe" or "anti-slip" frequently lack current independent certification. Request DIN 51097 test certificates from a UKAS-accredited laboratory before specification.
Mistake 3: ignoring cleaning chemical effects
DIN 51097 testing uses soapy water. Pool deck cleaning chemicals can be harsher than soap — strong chlorine-based cleaners, acid washes, or descalers can temporarily reduce wet barefoot PTV during cleaning cycles. Bi-annual testing captures cleaning chemical build-up before it becomes an incident.
For UK hotel and leisure operators
UK hospitality venues operating spas, swimming pools, or wet barefoot areas face a disproportionate slip claim risk. A DIN 51097 Class C specification for all wet barefoot areas, combined with annual UKAS-accredited re-testing, forms the core of a defensible floor safety programme. Documented testing supports both insurance renewals and any post-incident claims defence.