Sustainable slip resistance
A major international fast-food chain found that in some cases where slip-resistant flooring was installed in a busy restaurant, wear from many thousands of shoes (and the soil on them) could destroy the wet slip resistance in a few weeks or months. This company spent years devising a test to indicate whether a flooring sample was likely to give good slip resistance after years of heavy wear.
The test involves measuring the wet PTV of the sample when new, then subjecting it to a standard abrasion, then testing the wet PTV after abrasion. (For more, see C.J. Strautins’ papers, “Sustainable Slip Resistance: An Opportunity for Innovation,” presented at the Spanish conference, Qualicer in 2008 and “Enhanced Test Method for Assessing Sustainable Slip Resistance,” at the 2007 International Conference on Slips, Trips, and Falls). The specification is the wet PTV must be 35 or higher after 500 cycles of abrasion using a standard abrasive pad loaded with 1 kg (2.2 lb). When the sample meets this, it is said to have “Sustainable Slip Resistance.” Other large property owners, including two major cruise ship companies, are now having their candidate flooring samples tested for this Sustainable Slip Resistance.
Barefoot flooring
Another test worth noting was devised in Germany and adopted in modified form in Australia as AS/NZS 4586:2004, Slip Resistance Classification of New Pedestrian Surface Materials, Appendix C, “Wet/barefoot ramp test method.” This involves two technicians individually walking a wet 1-m (3-ft) long flooring sample in bare feet on a variable-angle ramp. The technician adjusts the ramp angle so he or she just barely can walk without slipping. Depending on the angle, the sample is classified as A, B, or C, with C having the greatest wet slip resistance. The A category is suitable, for instance, for locker rooms, while B is for swimming pool decks and C is for swimming pool ramps and steps leading into the water.
While the test is the most realistic one for barefoot situations, it is still a laboratory test and is impractical for checking quality of flooring after it has been delivered to the jobsite—or already installed. For onsite testing, the pendulum with a soft rubber slider is the preferred method of testing barefoot flooring.
A similar variable-angle test is used to rate flooring for industrial-type shoes having treads in oily situations, and is a standard in Germany and in Australia as the aforementioned AS/NZS 4586:2004 Appendices C and D (“Oil-wet Ramp Test Method”). However, the results are not applicable to general commercial situations where most pedestrians are not wearing shoes with effective treads.
When to test flooring
It is commonly assumed when a flooring sample is tested once, for instance for a catalog DCOF, that its slip resistance will always be the same. This has led to some expensive and embarrassing mistakes.
For a large project, experience has shown the flooring needs to be tested at four stages to protect the various parties involved:
- the architect or specifier;
- the general contractor;
- the installer; and
- the building owner.
The party being protected should normally be the one who pays for the test. Figure 1 shows when tests should be done and who should pay.
I have not been this confused about any subject in a long time. This article seems to be trying to describe a can of worms or possibly more applicable, a Medusa head of snakes, where the liability of all parties is in jeopardy due to the fact that a test was withdrawn with no replacement and we cannot trust the tile manufacturer’s COF numbers to be accurate. So, the specifier, or the firm for which the specifier works, is liable for any accident on the floor because there is no objective criteria to use to make a decision of what material or product to use. Then Figure 1 says the Architect is liable at the purchase order event, when the Architect didn’t write the purchase order. How does the Architect know that the slip resistance is not as advertised when a purchase order, that the Architect didn’t write, is created? This implies that the Architect needs to pay, out of their own pocket, for testing all the different types of tile on the project because there is no way to know that the slip resistance is not as advertised.
The same dynamic occurs when the Contractor has no idea whether the tile in the box that was delivered is not to spec. Then the Contractor needs to test all of the tile to protect themselves.
Then post-installation, according to Figure 1, the installer is liable? The poor installer didn’t pick the tile, the Architect did and barring a truly horrendous installation, it would be the tile that is slippery, not the installation. But, once the tile is installed, that is when the installed tile can be tested and if it does not pass, is it the tile manufacturer’s fault? After all, the Architect relied on the manufacturer’s (untrustworthy?) data to select the tile. And, there is no reason in the world why the architect should be required to pay to test a tile, that for all intents and purposes, does not yet exist, because there has only been a purchase order. What are they supposed to test? And, finally, the Owner is not going to accept liability for a tile installation. They will go back to the Contractor and Architect to get whole.
So we have a Hobson’s Choice, or a Catch-22. I have read my share of ridiculous standards over the years, but this one leads the pack further than Usain Bolt could ever dream.
This article is scholarly, detailed, well-researched and completely silly. Utterly ignores the reality of the construction process and the responsibility of the parties in the construction process.
The recommendations here are almost completely unfeasible as presented and are unlikely to be adopted in any North American construction project.
Also, the tile standards cited are not new, they were introduced in 2012 IBC, which is now being superseded by 2016 IBC. The article might be new.
The bio mentions that George Sotter is a member of ASTM, but there is a notable lack of mention of ongoing slip testing activities in Subcommittee F13.10 related to standardizing the slip testing industry. This group has already published F2508-16 Standard Practice for Validation, Calibration, and Certification of Walkway Tribometers Using Reference Surfaces and is working on additional standard WK47077 New Practice for Using Walkway Tribometry Data in Estimating Pedestrian Slip Resistance Thresholds and Comparative Traction.
There has been extensive research relatively recently at the University of Southern California that finally attempts to correlate slip test (tribometer) measurements to actually slipping tests on human subjects. The ASTM standards are born out of some of this research and may soon become THE standard for slip testing. Our firm rarely gets involved with slip testing. However, the industry generally seems to be fragmented, with various experts defending their own test equipment (which they often have a financial interest in promoting), and, therefore, standardization appears to be difficult to achieve.
The BOT 3000 device noted in this article did not correlate well with human slip tests in the USC study. However, there are two pendulum-type devices (also mentioned in this article) that did perform well. I think mentioning this research and the ongoing work at ASTM would be helpful and perhaps provide some clarity to readers of this article, at least about the direction of the industry.
My feet are like very good bourbon. (yes, really) To make really good Bourbon (25, 50 and 100 year blends) requires a specialized person with extraordinary taste buds. Their taste buds are so precise and sensitive, that they can detect even the most minute changes to the blend, allowing them to come up with an amazing final product. As a manufacturer of waterproofing products (including deck coatings) I’ve been asked many times over the years to show that my deck coatings will not be a slip hazard, especially when wet and/or raining. It’s easy to add slip resistant additives to sealers, but will they really work, especially when wet? I’ve come to trust my feet over any test out there.
1. Apply deck coating to large sample board (4’x4′)
2. Allow to fully cure.
3. Put on old dress shoes that the souls have worn out (so they have the least amount of rubber/traction)
3. Rub your feet over the floor surface. Most importantly is to put one foot way out front (almost at 45° to the floor surface) and rub your shoe back and forth. Most people slip when their foot is extended forward, and when they set it down on the floor it slips forward. If it feels too slippery, don’t use it.
4. Pour water on the sample So there is a lot of standing water on it) and repeat step 3. The wet test is the most crucial one. After you do this a few times, one quickly develops a good sense and feel as to what is acceptable and what is not.
The conflict: In principal, the rougher the surface, the better the traction. BUT…, it’s much harder to clean. All too often, the demand for easy cleaning influences the decision leading to materials that simply don’t have sufficient slip resistance.
I am all in favor of standardized (measureable) tests that will give dry and wet friction results. If you ask me, build a device mimicking a human foot at 45° angle to the floor, and mount a dress show that the grooves on the souls have been ground smooth. Now push this device down and forward on the floor (both wet and dry) and you should have a pretty good idea where you stand. Maybe additional tests will need to be added to resemble other conditions, but this should give you a pretty good idea on where a product really stands.
I have seen slip resistant test results all over the place, which in many cases did not reflect how that product will behave in the “real world”. I then performed my own dry and wet tests while wearing dress shoes and could pretty much convince any specifier on the spot as to whether a product was acceptable or not. Don’t believe me? I’ve been manufacturing/selling deck coatings (and many other waterproofing systems) for over 30 years. Sqft of installed product: Millions! Lawsuits: ZERO!
This really isn’t that complicated.
Amir: I love the simplicity and the approach. Thanks.
With all due respect, perhaps you should stick to your professional expertise in manufacturing and selling deck coatings and waterproof systems. Please contact me for further consultation and National standard compliance. I am on linkedin and will send you any factual information, codes, standards or videos to either refute, backup or help explain where you may be confused or ill advised.
Scott: I would be interested in speaking with you. so, kindly call 301-775 -3602 when convenient for you……..thanks.
Hi Scott, I am adjuster investigating a slip and fall claim in FL. I am tasked with reviewing a photo/video of a slip and fall on exterior ceramic tiles and they are asking if the tiles meet FL code. Would you kindly be of assistance? Are there any codes in FL speaking to the surface texture of exterior ceramic tiles in a commercial setting?
David,
I hope you got an answer before this time. Yes there is a commercial code requirement ANSI A137.1 and the method of testing A326.3.
Minimum DCOF values for level surfaces from the new ANSI A326.3 (with specific project conditions):
Interior, Dry (ID) 0.42 (p.2 of the standard)
Interior, Wet (IW) wet with water 0.42 (p.2)
Interior, Wet Plus (IW+) wet plus (as declared by manufacturer; including barefoot areas) 0.50 (p.5)
Exterior, Wet (EW) wet 0.55 (p.5)
Oils/Greases (O/G) 0.55 (p.6)