If you specify or buy flooring based on a minimum wet dynamic coefficient of friction of 0.42, you may be vulnerable to charges of negligence if a slipping injury occurs on that floor. Here we tell you why, and how to avoid the situation.
American National Standards Institute (ANSI) issued its standard A137.1, “Specifications for Ceramic Tile,” in 2012. The standard, also known as the AcuTest, is incorporated by reference in the 2012 International Building Code, which is used throughout the United States and in several other countries. The code specifies a minimum wet dynamic coefficient of friction (DCOF) of 0.42 “for tiles in level interior spaces expected to be walked upon wet.” The test uses a hard rubber slider to simulate the heel of a dress shoe.
Does this mean that a tile is safe if it has a wet DCOF of 0.42? Absolutely not.
The standard goes on to state that, “Tiles with a DCOF of 0.42 or greater are not necessarily suitable for all projects. The specifier shall determine tiles appropriate for specific project conditions, considering by way of example, but not in limitation,
- “type of use,
- expected contaminants,
- expected maintenance,
- expected wear, and
- manufacturers’ guidelines and recommendations.”
Tile Council of North America (TCNA) has added to this list. They state that the possibility of a slip may be affected by
- The material of the shoe sole and its degree of wear
- The speed and length of stride at the time of a slip
- The physical and mental condition of the individual at the time of a slip
- Whether the floor is flat or inclined
- How the surface is used
- How the tile is structured
- How drainage takes place if liquids are involved
ANSI and TCNA give no guidance as to how all of these items should factor into a higher DCOF or slip resistance, if needed, and most flooring manufacturers give no slip resistance guidelines or recommendations whatsoever. The TCNA goes on to state that through their own extensive research, the ANSI A137.1 test method results have been shown to closely correlate to the now-withdrawn ASTM C1028 test method that has been wreaking havoc across the United States for decades since many tiles can “pass” the C1028 test while still being extremely slippery when wet. C1028 was withdrawn by the ASTM in 2014 since it was a very bad test that was basically responsible for thousands upon thousands of needless slip and fall accidents across the country annually by spreading misinformation about the actual real-world slip resistance of various flooring materials.
Do you duly consider all of the above 16 listed items when you specify, buy or sell flooring? (Does anybody?) Certainly these published lists can expose people on the buying side, and perhaps in the whole chain of supply as well, to accusations of negligence. And negligence is something that plaintiff lawyers love to see when their client has had an expensive and debilitating injury.
How can people do a better job for themselves and the public than just looking for a minimum DCOF of 0.42? How much higher should it be? Should it be 0.50, 0.60, 0.80? (Just as a point of reference, American and European standards require that a basketball court floor have a dry coefficient of friction of 0.97 or higher.)
Help Arrives from Down Under
Fortunately there’s helpful and proven guidance for a large number of specific situations, and it’s described in a recent entry on this blog. Briefly, a minimum wet Pendulum Test Value (PTV) for the flooring is used as a specification for a given situation. For instance, a hotel bathroom should have a minimum wet PTV of 20 (measured using a soft rubber slider to simulate bare feet or soft shoe bottoms). Restrooms in offices and shopping centers, where people might be moving faster, should have a PTV of 35 or higher. That higher minimum also goes for bathrooms in hospitals and aged care facilities, because the people involved there are at high risk.
Communal shower rooms should have a minimum wet PTV of 40, and swimming pool ramps and stairs leading into water should have at least 45.
Those are typically barefoot areas, but there are also many standards for indoor areas where shoes are worn: building entries (PTV of 35 or higher), commercial kitchens (45), balconies, verandas, roof decks, cold storage walk-in freezers (40), etc. There are safety standards for other outdoor areas as well. (Remember, ANSI A137.1 only applies to indoors.)
Does this system make more sense than a one-size-fits-all minimum such as 0.42 after which the customer must make important decisions based on no advice or data whatsoever? The Australian standard we refer to is a minor revision of one that’s been in effect since 1999. We think that’s something to hang your hat on when you try to prevent injuries — or to defend yourself in court. The pendulum test instrument used in this situation-specific test has been testing floors involved in actual real-world slip and fall accidents in the United Kingdom since the 1950s, so the research into these safety standards are unparalleled with any other instrument or test method. It’s used in at least 49 nations on five continents.
The ANSI A137.1 DCOF of 0.42 is a very easy criterion for a tile to meet, and so the “specific project conditions” listed by ANSI and TCNA (see above) would be very important. A tile with wet DCOF of only 0.42 from this test could be extremely hazardous in many situations.
ANSI has a better test for assessing floor slip resistance: ANSI B101.3. It’s very similar to A137.1 but has twice the wetting agent in the wetting water used for the test. This usually results in a lower DCOF for the same tile. The same instrument, the BOT-3000E, is used for both tests. (ANSI B101.1, static coefficient of friction, should not be used for assessing safety.) ANSI B101.3 is backed up by extensive laboratory research on actual human traction, whereas ANSI A137.1 is not.
Safety Direct America conducts ANSI B101.3, B101.1, A137.1, and pendulum tests in the laboratory and in the field, using both hard and soft rubber sliders as appropriate. We do this floor slip resistance testing work for commercial buildings, major cruise ship companies, tile vendors, attorneys, and many others. For more information see our web site or contact Dr. George Sotter at 1-800-916-2193.