Can painted surfaces become more slippery when wet?
Painted pedestrian surfaces can become more slippery when wet because line marking paint, coatings, sealers and worn surface treatments can reduce surface texture and change how footwear contacts the ground. Under AS 4663:2013, existing painted surfaces should be tested in service where wet pedestrian use is reasonably foreseeable.
Wet pendulum slip testing is the test method used under AS 4663:2013 to measure the slip resistance of existing pedestrian surfaces where water may affect pedestrian safety.
Why can painted surfaces create slip risk?
Painted surfaces often look safer because they are used to mark pedestrian zones, crossings, accessible bays, walkways, safety lines and directional paths. The marking is visual, but the slip risk is physical. Once paint or coating is applied, the pedestrian is no longer walking on the original concrete, asphalt, tile or paving surface. They are walking on the finish.
That finish may be smoother than the surrounding surface. It may also wear unevenly, polish under traffic, hold water differently, or become contaminated by tyre residue, cleaning products, dust, oil, leaves or general site grime. In dry weather the surface may appear sound. In wet weather, the same surface can behave differently underfoot.
This is why visual inspection alone is not enough. A painted pedestrian zone can look maintained while still underperforming when wet.
Where are painted surfaces most likely to matter?
Painted slip risk is most common where a surface is marked to guide pedestrian movement. This includes pedestrian crossings, car park walkways, accessible parking bays, loading zones, ramps, painted steps, school pick-up areas, shopping centre crossings, public facility entries and painted paths through shared vehicle-pedestrian areas.
The risk is higher where people are expected to change direction, step from one surface to another, push trolleys, carry items, use mobility aids, move quickly through rain, or walk across areas where vehicle contamination is present. Car parks are a clear example, but the issue is broader than car parks. Any painted or coated walking surface can become part of the risk profile once water is present.
Does line marking change the slip resistance of the original surface?
Line marking can change the slip resistance of the original surface because it creates a new walking layer over the base material. The base concrete, asphalt or paver may have adequate texture, but the applied marking may not perform the same way. The final result depends on the paint system, aggregate content, application thickness, wear pattern, drainage, surface preparation and environmental exposure.
A non-slip additive may improve performance, but it should not be assumed to solve the risk unless the finished surface is tested. The question is not whether the marking was described as “anti-slip.” The question is how the installed surface performs under the conditions pedestrians actually encounter.
Why does winter increase the risk?
Winter increases the risk because painted and coated surfaces are exposed to more frequent wetting, slower drying, wind-driven rain, pooled water and contamination. A surface that is only occasionally wet in warmer months may stay damp for longer in winter, especially in shaded entries, covered car parks, access ramps and south-facing walkways.
The issue is not rain alone. Water mixes with surface contaminants, tyre residue, leaf matter, cleaning residue and worn coatings. That combination can reduce available friction at the point where a person’s shoe meets the surface. Where pedestrian movement is frequent or the surface is part of an access route, the risk becomes more foreseeable.
When should painted surfaces be tested?
Painted surfaces should be tested when they are used as pedestrian walking areas and may become wet during normal use. Testing is especially important after new line marking, repainting, resurfacing, coating, sealing, pressure cleaning, complaints, near misses, incidents or visible wear.
Testing should also be considered before applying a new paint or coating system across a high-use pedestrian area. For new surface materials or coating systems, AS 4586:2013 can be used to classify slip resistance before installation. Once the surface is installed and available for pedestrian use, AS 4663:2013 applies to the existing pedestrian surface.
Is dry floor friction testing enough?
Dry floor friction testing is not enough where the pedestrian surface is external or where wet conditions are reasonably foreseeable. Dry testing can be relevant for internal pedestrian surfaces that are expected to remain dry, but it does not assess wet-weather performance.
For painted external walkways, car park crossings, ramps, outdoor pedestrian routes and areas exposed to rain or tracked-in moisture, wet pendulum testing is the appropriate method. The test should match the real-world condition that creates the risk.
What should property managers and councils do?
Property managers, facility managers and councils should treat painted pedestrian surfaces as part of the walking surface, not just as signage. If people are directed to walk on it, the surface should be capable of supporting safe pedestrian use in the conditions likely to occur on site.
A practical approach is to include painted crossings, walk zones, accessible bays, ramps and public pedestrian interfaces in routine slip resistance testing. Where test results are low, options may include surface treatment, re-marking with a suitable aggregate system, improved drainage, cleaning review, matting controls, surface replacement or traffic management changes.
Applicable standards
AS 4663:2013 — Slip resistance measurement of existing pedestrian surfaces
Used for testing existing pedestrian surfaces in wet and dry conditions, including surfaces already installed and available for pedestrian use.
AS 4586:2013 — Slip resistance classification of new pedestrian surface materials
Used for classifying new pedestrian surface materials before installation, including products and treatments intended for wet or dry use.
Zerofal conducts slip resistance testing to the relevant Australian Standard and prepares reports suitable for compliance records, WHS review, asset management and insurance-related documentation.
Frequently Asked Questions
Can painted concrete become slippery when wet?
Painted concrete can become slippery when wet if the paint or coating reduces surface texture or becomes polished, worn or contaminated. The concrete underneath may have adequate texture, but pedestrians walk on the painted finish. Wet pendulum testing under AS 4663:2013 confirms how the painted surface performs in service.
Should car park line marking be slip tested?
Car park line marking should be slip tested where pedestrians walk across painted markings, crossings, accessible bays, walk zones or shared vehicle-pedestrian areas. Wet conditions, tyre residue and coating wear can change surface performance. Testing confirms whether the finished surface provides appropriate slip resistance under real site conditions.
Is anti-slip paint enough to prove a surface is safe?
Anti-slip paint is not enough by itself to prove a surface is safe. The installed result depends on the product, application, aggregate, wear, cleaning and exposure. A surface described as anti-slip should still be tested where pedestrian use and wet conditions create foreseeable risk.
Which standard applies to painted surfaces already in use?
AS 4663:2013 applies to painted pedestrian surfaces already installed and available for use. AS 4586:2013 applies to new pedestrian surface materials before installation. Once a surface has been installed and opened to pedestrian traffic, it is treated as an existing pedestrian surface.
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 to test a painted or coated pedestrian surface?
If a painted surface is used by pedestrians and may become wet, it should be tested under real site conditions.
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