What You Need to Know About the ANSI A137.1/A326.3 Tile Slip Test

If you specify or buy flooring based on a minimum wet dynamic coefficient of friction (DCOF) of 0.42 referred to in the 2012 International Building Code, (IBC) 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.

The ANSI A137.1 standard applies only to ceramic tile in the Code, but we know of no reason why the safety standard for ceramic tile should be different from that of any other hard, resilient, or wood flooring. We don’t change our shoes when we walk from marble to hardwood to ceramic tile, so why would we change test methods and safety standards? And why should ceramic tile have an advantage or disadvantage over other flooring when setting a safety minimum?

The ANSI A137.1 Tile Slip Test, which is now (by reference) a part of the 2012 International Building Code, has not been based on reliable slip and fall research, and you should not rely on it as a test to determine slip risk on a particular type of flooring. The stated purpose of the Code is to establish minimum requirements. The ANSI A326.3 tile slip test uses the exact same test method, but adds more disclaimers and describes the method for testing in the field, as A137.1 was intended only as a lab test.

American National Standards Institute (ANSI) published their current revised A137.1, “Specifications for Ceramic Tile,” in 2017. The test specified, sometimes referred to as the DCOF AcuTest, is used within the United States and a few smaller countries. The “DCOF Rating” test is conducted using the BOT-3000E digital tribometer. The photos at right show the BOT’s top, undercarriage, and the curved hard rubber slider that simulates a shoe heel. ANSI officially released ANSI A326.3 in January of 2018 to essentially replace A137.1.

The code requires a minimum wet dynamic coefficient of friction (DCOF) of 0.42 “for tiles in level interior spaces expected to be walked upon wet.” A DCOF rating of 0.38 using this test method, according to the TCNA research mentioned below, has been found to closely correlate with the old 0.60 SCOF number from the now-withdrawn ASTM C1028 static coefficient of friction (SCOF) test. That test was not based on scientific slip and fall research either, and the ASTM finally withdrew that test method in 2014. It is no longer a current test method and there are, thankfully, no plans to ever resurrect that very poor test method that has been causing slip and fall accidents and billions in ill-advised flooring purchases all over the USA for many years. The Tile Council of North America (TCNA) states that through their own extensive research, the results from ANSI A137.1 and ASTM C 1028 have to been shown to correlate closely. That means that like the (now-withdrawn) ASTM C1028 test results, the ANSI A137.1 test results should never be trusted as a reliable indicator of slip resistance. Achieving a 0.60 SCOF using C1028 never meant that you had a safe floor when wet, and achieving a 0.42 using this newer test method is just as unreliable as an indication of safety. The latest version of this test, the ANSI A326.3 floor “DCOF Rating” test, in fact states “The coefficient of friction (COF) measurement provided in this standard is an evaluation of hard surface flooring materials under known conditions using a standardized sensor material prepared according to a specific protocol. As such it can provide a useful comparison of surfaces, but does not predict the likelihood a person will or will not slip on a hard surface flooring material.”

So does a wet DCOF rating of 0.42 mean the tile is safe for use in a wet area? Absolutely not. If the DCOF were a “passing grade” in school, 0.42 would be equal to a D minus. ANSI A 137.1/A326.3 sets a low bar: a minimum DCOF (0.42) that most tiles exceed no matter how slippery they are in real world situations. It does not ensure safety. That’s the buyer’s job. There are much more reliable slip resistance test methods available to ascertain what your real-world slip risk will be. Click on reliable tile slip testing or head over to SafetyDirectAmerica/Floor-Friction-Testing to get more information on what tests you can do to minimize your negligence and chances of a slip and fall on your tile or property. Safety Direct America also performs the ANSI A137.1/A326.3 tile slip test (DCOF rating) for code compliance purposes.

Click on ANSI A137.1 Disclaimers to read what disclaimers ANSI and TCNA have written into this test method.

The BOT-3000E Slip Tester
used in the A137.1 slip test
BOT-3000 tribometer - slip test
BOT-3000 tribometer bottom - A137.1
BOT-3000E rubber slider