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Wet vs Dry Slip Resistance: Why Testing Both Matters
Wet slip resistance measures how much grip a floor surface provides when water or another liquid is present, and it is almost always lower than the same floor’s dry reading. A floor can pass comfortably when dry and still fall well below a safe threshold once wet, which is why testing only one condition gives an incomplete, and potentially misleading, picture of a floor’s actual risk.
A passed test doesn’t tell you which test it passed
As a Facilities Manager in hospitality, you’ve likely got a test certificate for at least some of your flooring. Maybe it came with the floor when it was installed, maybe it followed an incident. Either way, it probably says the floor is compliant, and that’s reassuring, right up until you ask exactly what conditions that test was carried out under.
This is where the old belief starts to break down. We test, so we’re compliant treats a test certificate as a single, settled fact. But a slip resistance reading is only meaningful in the context of the conditions it was taken under, and wet versus dry is the single biggest variable in that picture. The shift this article makes is simple: measure both, improve where either falls short, and keep proving it over time.
What is wet slip resistance, exactly?
Wet slip resistance refers to a floor’s measured grip when tested with water present on the surface, typically using a pendulum test, which simulates a heel strike and produces a Pendulum Test Value (PTV). The lower the PTV, the more slippery the floor is under those specific conditions.
Wet testing exists because water dramatically changes how a floor behaves underfoot. Many flooring materials that feel grippy and perform well dry lose a significant amount of that grip the moment moisture is introduced, and the reverse is rarely true.
Why does wet performance matter more than dry in most venues?
For a hospitality venue, water isn’t a rare event. Entrances get wet during rain. Pool surrounds are wet by design. Bar areas see spills. Kitchens have washdown routines. Most of the zones where people actually slip are the zones most likely to be wet at the time.
A floor’s dry PTV reading tells you very little about how it will perform in exactly those moments. If a certificate only reflects dry testing, it’s answering a question that matters far less than the one your venue actually needs answered.
Why does the same floor test so differently wet and dry?
The physics behind this comes down to friction. A dry floor allows direct contact between a shoe sole and the surface texture. Water introduces a thin film that reduces that direct contact, and on smoother or more worn surfaces, that film can dramatically cut the available friction.
This is also why floor material and condition matter so much. A textured surface that channels water away performs very differently wet compared to a smooth surface that traps a film of moisture on top. Two floors that look similar, or even test similarly dry, can behave in completely different ways once wet.
How does this connect to the wider slip risk picture?
Wet and dry testing is one part of a fuller diagnostic. Using the CHIMES framework helps place wet slip resistance in context alongside the other factors that drive risk:
- Contamination: is the zone regularly exposed to water, grease or other liquids, which makes wet performance the priority reading
- Heel: does footwear change with the wet conditions, bare feet by a pool versus wet-weather shoes at reception
- Individual: who’s exposed to the wet zone, and how often
- Maintenance: are cleaning products or methods introducing moisture or residue that affects grip
- Environment: are there transition points between wet and dry areas where risk concentrates
- Surface: is the floor material itself suited to performing well under both conditions
Running through CHIMES for a specific zone tells you whether wet testing should be the priority, or whether dry performance matters more, depending on how that space is actually used.
What does proper wet and dry testing actually involve?
Good testing isn’t a single visit with one reading taken in one spot. It typically involves:
- Testing the same zone both wet and dry, so you have a complete picture, not half of one
- Focusing wet testing on zones where water is a genuine, regular presence, entrances, pool surrounds, bar areas, kitchens
- Recording both readings against a recognised scale, so future comparisons are meaningful
- Repeating tests at sensible intervals, since floors change with wear, cleaning and footfall over time
Skipping the wet reading because the dry one came back fine is exactly the gap that leaves a genuine risk unmeasured.
Why isn’t one good test result enough?
This is the core of the old belief worth retiring. A single test, wet or dry, tells you about conditions on the day it was taken. Floors wear. Cleaning products change. Footfall increases. A wet PTV reading from installation says very little about how that same zone performs two or three years later.
Slip Safety Services has found that organisations who measure both wet and dry conditions, and keep re-testing over time, see a 57%+ average reduction in slip incidents. The improvement comes from having the complete picture, not from a single certificate filed away and forgotten.
What good looks like
A venue managing this well has both wet and dry PTV readings for every zone where water is a realistic presence, not just a dry reading taken once at installation. High-risk zones, entrances, pool surrounds, bar areas, kitchens, are tested and re-tested on a sensible schedule. Cleaning regimes are matched to how each zone actually performs wet, not assumed from a dry-only result. And when anyone asks how a specific area performs under real conditions, there’s a dated wet and dry reading to hand, not a single certificate from years ago.
The takeaway
A dry test alone tells you half the story, and often not the half that matters most. The belief worth carrying forward is simple: measure both wet and dry, improve where either falls short, and keep proving it as conditions change.
Next step
If you’re not sure whether your venue’s floors have ever been tested wet, the Slip Prevention Scorecard takes a few minutes and gives you a clearer picture of where the gaps might be. For a proper wet and dry reading of your highest-risk zones, a professional slip test gives you the full data. And for the fuller method behind measuring, improving and proving floor grip, Slipology by Christian Harris covers the process in depth.
FAQ
Why is wet slip resistance different from dry slip resistance?
Water forms a thin film between a shoe sole and the floor surface, reducing the direct contact that creates friction. This means a floor can perform well dry and still test poorly once wet, particularly on smoother or more worn surfaces.
Do I need to test my floors wet if they’re usually dry?
If a zone is rarely exposed to water, dry testing may be sufficient. But most hospitality venues have several zones, entrances, kitchens, bar areas, pool surrounds, where water is a regular occurrence, and those zones should be tested wet as a priority.
What’s a safe PTV score when a floor is wet?
A PTV of 36 or above is generally considered low slip risk, based on HSE-recognised guidance. This threshold applies to the specific conditions tested, so a wet reading needs to meet that threshold independently of any dry reading.
Can a floor pass a dry test and still be dangerous when wet?
Yes, and this is one of the most common gaps in slip risk management. A floor can look and test perfectly safe dry while dropping well below a safe threshold the moment it’s wet, which is exactly why both conditions need to be measured.
How often should wet slip resistance be retested?
High-risk, frequently wet zones should be tested at sensible intervals, generally at least annually, and re-tested whenever cleaning products, footfall or the floor itself changes. A single wet reading from years ago doesn’t reflect how the floor performs today.