What is a good slip rating? Is there more to slip resistance than identifying slippery surfaces?
Here we chat with materials testing specialist Kate Tonkin, head of the finish evaluation department at Stone Initiatives. Kate shares some insights into the methods, processes, risks and responsibilities around slip resistance testing.
Interview with Kate Tonkin
What kind of surfaces do you test?
In terms of what we can slip test, it extends far beyond natural stone. We can test tiles for bathroom floors, external tiles, tactiles for accessible floors, vinyl, carpets, concrete finishes, synthetic grasses, sports courts … really anything that you can walk on – other than dirt!
It is the finish that will be in use that is tested, rather than the raw material. And that’s really important to note. You shouldn’t, for example, test a honed stone product without a sealer and then install it with a sealer, as the sealer could affect the slip resistance.
How is slip resistance measured?
Slip resistance in Australia is measured according to two different (but similar) standards depending on whether the surface is new or existing. New pedestrian surfaces are tested in accordance with the current version of AS 4586, while existing pedestrian surface are tested in accordance with AS 4663.
The standard for new pedestrian surfaces (AS 4586) provides a method for determining dry slip resistance (using a Floor Friction tester) and a range of different methods for evaluating slip resistance in a wet condition – these include the Wet Pendulum test, the wet barefoot inclining platform test, and the oil wet ramp test.
For wet slip resistance, only one of these methods, the Wet Pendulum, can be used in both a lab setting and on site. It measures the frictional resistance between a rubber slider mounted on the end of a pendulum arm and the test surface. The Wet Pendulum is the test method we primarily use at Stone Initiatives as it provides results that are analogous to pedestrian traffic and is sensitive to minor changes in the surface finish. The dry floor friction test can also be tested both in a lab setting and on site, however, it is predominantly used to test surfaces in areas that are meant to be kept dry.
The pendulum consists of an arm that rotates about a spindle attached to a vertical support pillar. At the other end of the arm is a mass (shaped like a foot) fitted with a spring-loaded rubber slider.
What is a good slip rating?
Slip resistance ratings give an indication of the surface’s slipperiness and its capability to reduce the risk of slip accidents. Wet Pendulum testing gives a P-rating from P0 to P5 – for example, toilet facilities in public buildings require a P3 rating, whereas internal areas that are kept clean and dry at all times require a P1 rating. A ‘good slip rating’ depends on the specific requirements for the project. The Standards Australia handbook HB198:2014 provides a guide to slip resistance recommendations for location types, and this can also be found here on our website.
What stage of a building project should slip resistance testing occur?
At the selection stage, when you’re choosing what kind of finishes you’d like for the project – and ideally, again after installation and regularly after that.
If you start out testing a particular finish and it’s not getting the results you need for use in your project, you can change the finish and test again to make sure you get it right before installation. It’s much easier to make changes before you install your surface, rather than trying to fix it later.
Does slip resistance change over time, and if so, are slip tests needed regularly?
Slip resistance can change dramatically with wear, and that’s why regular surveillance tests are recommend, especially for high-risk areas. We recommend six-monthly to yearly for public areas, particularly for high-traffic spaces such as a public bathrooms and malls. Regular testing can also pick up things like accelerated wear, or whether the cleaning regime might be impacting the slip resistance. If you’re not using appropriate cleaning products or methods, it might wear the surface more quickly.
“Slip resistance can change dramatically with wear, and that’s why regular surveillance tests are recommend, especially for high-risk areas.”
It’s really a team effort to make sure the surface is selected, installed, maintained and cleaned in the most appropriate way.
What are the risks of not completing appropriate slip resistance testing on a project?
The risk is that you have a surface that’s not compliant and somebody slips, which could expose you to legal action. Without the correct tests you have nothing to fall back on to say that the surface achieved the appropriate ratings. Aside from the risk of someone being injured, there is also the risk of having to spend more time and money after installation to fix the problem.
Who is responsible for slip testing?
We suggest that building managers, owners, and all parts of a design, construction or installation team know their legal duty of care and compliance obligations. All organisations have a duty of care to their customers or employees to provide a safe environment, including floor surface safety.
The risk of not testing is that you have a surface that’s not compliant and somebody slips, which could expose you to legal action
A report by the Monash University Accident Research Centre states that “slips, trips and falls in buildings constitute a large and costly public health problem,” and that many potential solutions lie with the building industry and its regulators. What roles does slip resistance testing play in this?
Regular slip resistance testing in public areas is clearly important in keeping flooring surfaces safe and helping to reduce slip incidents. But having the tests performed and receiving the results is only part of the process – it’s vital that action is then taken when needed. When testing an existing surface, our reports include comments that indicate whether the surface would pass or fail if it was tested as a new surface. We explain results to help our clients understand what the numbers mean, so they can take any required action promptly.
“Having the tests performed and receiving the results is only part of the process – it’s vital that action is then taken when needed.”
Do aesthetics need to be sacrificed in order to meet slip resistance requirements?
Sometimes they do, to an extent. For example, in a public bathroom, you can’t really have a polished tile on the floor, as you’re not going to get the slip resistance rating you need. However, we can work with designers and specifiers to help them find a balance between their aesthetic desires and achieving the appropriate slip ratings. This could involve suggestions for alternative finishes or micro-etching, for example.
What’s something surprising you’ve discovered in your years working in slip resistance testing and finishes evaluation?
You can just never tell the results from feeling or looking at a stone – testing can often reveal surprising things that are almost the complete opposite to what you might have assumed just from looking at the product!
Also, wet surfaces can be less slippery than dry surfaces, which is surprising to a lot of people. It’s usually with a ceramic tile – when wet, the suction of the micro pores can reduce the slipperiness, whereas when it’s dry, especially if it’s dusty, it can actually be really slippery. And that brings us back to why appropriate and timely testing is so important.