Wet pendulum test: the on-site method for existing floors
The wet pendulum test is the primary method in AS 4663:2013 for measuring the slip resistance of a floor that is already installed. A rubber slider on a swinging pendulum arm sweeps across the wetted surface. The friction it meets becomes a British Pendulum Number, which maps to a P classification from P0 to P5.
Slip Audit conducts wet pendulum testing on site in Melbourne, Sydney and Brisbane, then interprets each result against HB 198:2014 for that location type. Use this page for the method itself. The full classification table and handbook context sit on our slip resistance standards guide, and you can convert a reading with the P rating checker.
A portable instrument, testing the floor you actually have
The pendulum is brought to the location. The surface is wetted, a conditioned rubber slider is swung across it a defined number of times, and the mean British Pendulum Number is calculated. That number maps to a P class. Because the test happens in place, the result includes wear, polish, sealer and cleaning residue — the conditions pedestrians actually walk on.
- Wet conditions. Most slips happen on wet or contaminated floors, so this is usually the priority method.
- Calibrated equipment. Instruments are maintained and calibrated, with verification checks before testing begins, under a documented quality management system.
- Minimal disruption. Each location only needs a small area temporarily cordoned. After-hours visits are available for trading and sensitive sites.
Where we typically use it
- Entry foyers and lobbies that get wet
- External ramps, walkways and forecourts
- Stair treads and landings
- Bathrooms, changerooms and wet areas
- Food courts, cafes and kitchens
- Retail floors and supermarket aisles
- Aged care corridors near wet areas
- Warehouse walkways and loading areas
P ratings from the wet pendulum
Higher is grippier when wet. What counts as acceptable depends on the location. Check a reading yourself with the P rating checker, or read the full standards context on AS 4663, AS 4586 and HB 198.
| Classification | BPN range | What it means in practice |
|---|---|---|
| P5 | Greater than 54 | Very high wet slip resistance. Suitable for demanding external locations such as steep ramps. |
| P4 | 45 to 54 | High wet slip resistance. Commonly recommended for external walkways and wet public areas. |
| P3 | 35 to 44 | Moderate wet slip resistance. Commonly recommended for locations such as entry foyers that get wet. |
| P2 | 25 to 34 | Limited wet slip resistance. Generally only appropriate where surfaces stay dry. |
| P1 | 12 to 24 | Low wet slip resistance. |
| P0 | Less than 12 | Very low wet slip resistance. |
Wet pendulum versus dry floor friction
Wet pendulum. Water on the surface. Result is a P rating. Use it wherever the floor can be wet or contaminated.
Dry floor friction. No water. A motorised instrument measures the coefficient of friction. Result is D1 at 0.40 or more, otherwise D0. Use it for corridors and office floors that stay dry in service.
A dry result alone cannot clear a surface that gets wet. Pairing both methods gives a complete picture. Slip Audit conducts both to AS 4663:2013.
When the wet pendulum is the right test
If people can walk the surface with water, rain, spills or cleaning residue on it, the wet pendulum is the method that answers the risk question. That covers most commercial entries, wet areas, hospitality floors and external paths.
If the only question is dry grip on a reliably dry internal floor, dry friction is the better benchmark. Many sites need both: wet pendulum at the door and wet rooms, dry friction along the office corridors.
R ratings from an oil-wet ramp test are a laboratory classification for new materials under AS 4586. They cannot be measured on an installed floor. The installed-floor answer is the pendulum.
Questions specifiers and facility managers ask
What is a wet pendulum test?
A wet pendulum test is the primary on-site method in AS 4663:2013 for measuring the slip resistance of an existing pedestrian surface. A rubber slider on a swinging pendulum arm sweeps across the wetted floor. The friction it meets is recorded as a British Pendulum Number, which maps to a P classification from P0 to P5. Because the instrument is portable, it tests the floor in place, including wear, polish and cleaning residue.
What do P0 to P5 ratings mean?
P ratings are wet pendulum classifications. P5 is the highest wet slip resistance and P0 the lowest. The British Pendulum Number maps to the class: P5 is greater than 54, P4 is 45 to 54, P3 is 35 to 44, P2 is 25 to 34, P1 is 12 to 24, and P0 is less than 12. No single class is universally compliant. HB 198:2014 recommends minimum classifications for different location types, such as entry foyers or external ramps. Convert a reading with the P rating checker.
When do I use a wet pendulum test instead of dry floor friction?
Use the wet pendulum wherever a surface can be wet or contaminated in service: entries, ramps, stairs, bathrooms, kitchens, food courts and external walkways. Most slips happen on wet floors, so this is usually the priority method. Dry floor friction testing is the right benchmark for surfaces that stay reliably dry, such as internal corridors and office floors, and produces a D0 or D1 classification. Slip Audit conducts both.
Can you do a wet pendulum test on an installed floor?
Yes. That is what the method is for. AS 4663:2013 is the standard for existing pedestrian surfaces. The pendulum is portable, so the floor is assessed as it actually performs on site. An oil-wet ramp test and its R ratings cannot be measured on an installed floor; those are laboratory methods for new materials under AS 4586:2013.
Is a wet pendulum test disruptive to the site?
Each location only needs a small area temporarily cordoned while it is tested. We schedule visits around operations, including after hours for trading retail sites, aged care and other sensitive environments, across Melbourne, Sydney and Brisbane.