Photo © Bigstock.com
Outdoor surfaces
At present, IBC lacks a specific slip resistance requirement for outdoor surfaces. However, this does not mean there is no problem. In fact, outdoor surfaces should meet a higher standard because people are conditioned to believe they can run when outdoors—especially when it starts to rain or hail. Sidewalks and roads are normally slip-resistant when wet. Someone who would not think of running on a polished marble indoor floor might not hesitate to run on an outdoor tile surface. Just because it is not glossy does not mean it is not slippery.
The Australian standards can be very helpful for outdoor situations. Generally, a wet PTV of at least 35 is required, and for a ramp with slope steeper than 1 in 14 (i.e. 4.1 degrees), a wet PTV of 55 or higher (tested with a hard rubber slider) is required.
The ANSI A137.1 slip resistance test is unsuitable for outdoor surfaces because the BOT-3000E instrument used is low in speed, and does not simulate someone walking fast or running. The pendulum test is more suitable.
Good safety engineering practice involves designing to prevent hazards to the extent feasible. It is not good practice to create a hazard, and then post warning signs. For one thing, such signs are not always noticed; for another, they give the pedestrian a Hobson’s choice—should she try to negotiate the hazardous area to get to work, or go back home and return to work when it is not raining?
Maintaining slip-resistant flooring
The architect or specifier is generally not responsible for ensuring the flooring is properly maintained. Nevertheless, they might be among those blamed for a slip and fall if the carefully chosen flooring is poorly maintained so it loses its wet slip resistance. Would you recommend using a broom and dustpan for routine cleaning of carpet? Most people opt for a vacuum cleaner instead, because it takes the soil away instead of mainly spreading it around. Hard flooring is often cleaned using a dirty mop and dirty water. This is analogous to cleaning a carpet with a broom and dustpan. The best way to clean hard flooring is to use an autoscrubber. The machine lays down the detergent solution, scrubs with a pad or brush, and uses a double squeegee with vacuum to pick up the dirty water.
Pads for autoscrubbers are color-coded, with anything other than white indicating abrasiveness. Abrasive pads must not be used if a floor is to retain good wet slip resistance. Even better than using a white pad is to use a very soft brush, like a carpet brush. Brushes have a higher initial cost, but last much longer than a pad; further, they will not shear off the small, sharp asperities on the floor surface that give the floor good wet slip resistance. Most autoscrubber pads used for general cleaning tend to polish the floor, making it smoother and more slippery when wet, whereas a soft brush will ‘tickle’ dirt out of grout joints and low points within the flooring to clean more effectively than a pad.
Monitoring slip resistance
Slip resistance can change with time due to wear or inappropriate maintenance. It is beneficial for many large property owners to have slip resistance monitored periodically—quarterly for high-traffic areas, and perhaps annually for less busy areas. Testing should be both dry and wet, if the floor can get wet in use.
Having written proof a routine testing plan is followed, and that any problems discovered are promptly rectified, both prevents accidents and attention from plaintiff attorneys. An accident on a dry floor may have been due to the pedestrian’s footwear having poor traction, but this does not stop the injured pedestrian from potentially suing the property owner and everyone else connected to it. A slip-resistance monitoring program can help prevent losses from frivolous lawsuits.
Conclusion
By incorporating ANSI A137.1, the 2012 IBC explicitly puts responsibility for floor slip resistance in the hands of the Specifier. It sets a rather low bar for minimum wet DCOF, but points out meeting the minimum dynamic coefficient of friction requirement is not enough—numerous other factors must be considered. (Specifiers should make sure their insurance covers this added risk.) However, using the methods discussed in this article can help avoid accidents and build a strong defense against litigation.
| KEEPING SLIPPERY FLOORS DRY |
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Most flooring, even if smooth and glossy, is slip-resistant when dry (to footwear having reasonable traction potential, anyway). Not all floors need be safe when wet—those slipperier surfaces can be used in places where the floor will be kept dry. Here are some precautions to ensure a floor stays dry in use:
A BOT-3000E display after four runs using the procedure in American National Standards Institute (ANSI) A137.1, American National Standard Specifications for Ceramic Tile. |
George Sotter, PE, PhD, is president of Sotter Engineering Corporation. His background includes rocket combustion research, air pollution control, and slip-fall prevention. He is a member of ASTM and is certified by the City of Los Angeles to test floor friction. Sotter authored the book, STOP Slip and Fall Accidents! He can be reached at george.sotter@safetydirectamerica.com.
John Sotter is a graduate of the University of California at San Diego in Urban Planning. He has many years of experience in responsible safety work for the City of San Clemente, California, and trained in floor friction testing in the United States and the United Kingdom. Sotter has worked for 15 years in floor friction testing and treatment in North America and on the high seas. He can be contacted via e-mail john.sotter@safetydirectamerica.com.
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)