When should wet pendulum testing be used instead of dry floor testing?
Wet pendulum testing should be used when a pedestrian surface is external, exposed to rain, affected by tracked-in water, or has a reasonably foreseeable risk of wet contamination. Dry floor friction testing is used for internal surfaces expected to remain dry. The test method should match the real use condition.
Wet pendulum testing measures the wet slip resistance of a pedestrian surface using a pendulum friction tester and standardised rubber slider.
Why the test condition matters
Slip resistance is not a single fixed property that applies in every situation. A surface can perform one way when dry and another way when wet. The correct test method depends on how the surface is used, where it is located and what contamination is reasonably foreseeable.
This is why wet pendulum testing and dry floor testing are not interchangeable. They answer different questions.
Wet pendulum testing asks:
How does this surface perform when wet?
Dry floor friction testing asks:
How does this surface perform in dry internal conditions?
Selecting the wrong test method can give a result that is technically valid but not useful for the actual risk.
When wet pendulum testing is appropriate
Wet pendulum testing is appropriate where water, rain, cleaning residue, pool water, tracked-in moisture or wet contamination may affect pedestrian safety.
Common examples include:
- external pedestrian paths
- ramps
- outdoor stairs
- building entries
- car park crossings
- painted walkways
- accessible parking bays
- pool surrounds
- change rooms
- public toilets
- commercial kitchen interfaces
- outdoor tiles and pavers
- areas exposed to wind-driven rain
- internal entry zones affected by wet footwear
Under AS 4663:2013, wet pendulum testing is used for existing pedestrian surfaces where wet slip resistance needs to be measured. For new pedestrian surface materials, AS 4586:2013 provides wet pendulum classification before installation.
When dry floor friction testing is appropriate
Dry floor friction testing is appropriate for internal surfaces expected to remain dry during normal pedestrian use. It is commonly relevant for commercial interiors, corridors, foyers, retail areas, office spaces and other pedestrian surfaces where the intended condition is dry.
Dry testing may be useful where the question is about dry internal performance, especially for smooth surfaces where wet exposure is not expected.
However, dry testing should not be used as a substitute for wet testing where water is likely to be present. If a surface is external, exposed to rain, or likely to receive tracked-in moisture, wet pendulum testing is usually the more relevant method.
Why dry testing is not enough for wet areas
A dry test result does not predict wet performance. A surface that performs well when dry may lose friction when water is added. This is especially important for smooth tiles, sealed concrete, coated surfaces, painted markings, polished stone, vinyl and some timber-look products.
Water changes the interface between shoe and surface. It can fill small surface texture, reduce contact, carry contaminants and create a lubricating film. That is why the wet condition needs to be tested directly where wet use is foreseeable.
How this applies to external areas
External pedestrian areas should generally be assessed using wet pendulum testing because rain and wet contamination are foreseeable. This includes areas that are covered but still affected by wind-driven rain, tracked-in water or slow drying.
Undercover does not always mean dry. A covered car park, colonnade, entry canopy or awning line may still become wet. If pedestrians use the area during wet weather, the surface condition should be assessed accordingly.
How this applies to entrances
Entrances often need careful judgement because they sit between external wet conditions and internal dry conditions. The first few metres inside a building may be exposed to tracked-in water, saturated mats, wet shoes, umbrellas and trolley traffic.
In these areas, wet pendulum testing may be required even though the surface is technically internal. The relevant question is not simply whether the floor is inside or outside. It is whether wet contamination is reasonably foreseeable.
How this applies to lab testing
For new pedestrian surface materials, AS 4586:2013 allows different test and classification methods, including wet pendulum and dry floor friction testing. Suppliers and specifiers need to choose the test method that matches the proposed use.
If a tile, paver, coating or flooring product is intended for external use, wet areas, entries, ramps or locations exposed to water, wet testing is usually necessary. A dry result alone may not support the intended application.
What should clients ask before testing?
Before booking a test, clients should ask:
- Is the surface internal or external?
- Can it become wet during normal use?
- Is water tracked into the area?
- Is the surface cleaned wet?
- Is the area near a pool, kitchen, toilet, entrance or car park?
- Is the surface sloped?
- Has it been coated, sealed, polished or repainted?
- Has there been a complaint, near miss or incident?
The answers help determine whether wet pendulum testing, dry floor friction testing, or both methods are appropriate.
Frequently Asked Questions
Is dry floor friction testing suitable for outdoor areas?
Dry floor friction testing is generally not suitable for outdoor pedestrian areas where rain or wet contamination is reasonably foreseeable. Outdoor surfaces should usually be assessed using wet pendulum testing because wet performance is the relevant risk condition.
Can an internal floor need wet pendulum testing?
Yes. An internal floor may need wet pendulum testing if wet contamination is reasonably foreseeable. This commonly applies to entrances, amenities, commercial kitchens, pool facilities, healthcare settings and areas affected by tracked-in rainwater.
Should ramps be wet tested?
Ramps should be wet tested where they are external or may become wet during use. Sloped surfaces can increase slip risk because pedestrians need more traction when walking up, down or across the surface.
Can both wet and dry testing be used on the same surface?
Yes. Both methods may be used where a surface is used in both wet and dry conditions, or where a fuller understanding of surface performance is required. The test selection should match the intended use and likely contamination.
written by:
Brendan Sheedy
Brendan Sheedy is the founder of Zerofal Slip Test Specialists. He leads Zerofal’s NATA-accredited slip resistance testing services and brings more than 20 years of experience in commercial facility management, flooring risk assessment and compliance testing.
Need help choosing the right test?
Zerofal can confirm whether wet pendulum testing, dry floor friction testing or both methods are appropriate for your surface.