ASTM D2047 is the current predominant slip resistance test method in the United States utilized on resilient flooring. Be aware that many manufacturers still report ratings from ASTM C1028 which was thrown out as invalid in 2014. The topic of slip resistance is controversial and can vary in requirement widely from state to state depending on which version of the International Building Code the state last adopted. Every three years, the building code is updated. Most of the sections outlining slip resistance for flooring refer only to ceramic tile. The ADA accessibility requirements do not overrule state or local laws that impose higher accessibility standards. When federal, state, or local codes differ, is best to follow the one that has the most stringent requirements. (OK.gov, 2021)
Making this trickier for specifiers, the actual ADA standards do not specify a minimum level of slip resistance (coefficient of friction) because an industry wide consensus surrounding the method for rating slip resistance remains elusive. (ADA, 2010) For decades, it was widely believed the Americans with Disabilities Act (ADA) required a static coefficient of friction, dry or wet, of 0.60 or higher for level floors and 0.80 for ramps. (Sotter & Sotter, 2016) In fact, that rating came from a research project sponsored by the Architectural and Transportation Barriers Compliance Board. (Access Board) They conducted tests with people with various disabilities and concluded that a higher coefficient of friction was needed to safely accommodate them. A SCOF of 0.6 was recommended for accessible routes and 0.8 for ramps. The ADA adopted this for a time but withdrew the recommendation in 2010 (McGee, 2017) because the recommendation was missing one important thing: it failed to specify a means of measurement. Even the Access Board of the U.S. Department of Justice has also disavowed any responsibility for this rating. (Sotter & Sotter, 2016)
OSHA, however, has long recommended a minimum coefficient of friction of 0.50 for workplace safety, but, once again, without specifying how the coefficient of friction is to be determined. (Sotter Engineering Corporation, 2020) Written verbiage in ANSI standards addressing DCOF refer to tile without including other types of flooring. In the 2012 edition of the IBC, ANSI 137.1 was included as a guide for DCOF.
In 2014, (ANSI) A137.1, American National Standard Specifications for Ceramic Tile, was revised to read: “[DCOF] does not predict the likelihood a person will or will not slip on a tile surface.” It goes on to recommend a minimum of .42 for a tile floor based on the ASTM D2047 testing method, but then adds “The specifier shall determine tiles appropriate for specific project conditions, considering by way of example, but not in limitation, type of use, traffic, expected contaminants, expected maintenance, expected wear, and manufacturers’ guidelines and recommendations” TCNA added to this essentially explaining that there are many different factors that can further impact slip resistance possibly in efforts to limit the statement of liability of the specifiers, but neither ANSI nor TCNA offer any method to evaluate those additional variables. This goes back to central challenge with rating slip resistance in flooring. (Sotter & Sotter, 2016)
While different measurement devices and protocols have been developed over the years for use in the laboratory or the field, a widely accepted method still has not emerged (US Access Board , n.d.) and different slip resistance test methods will give different results, particularly under wet conditions. A key challenge with all the testing methodologies is that the tests cannot consider important variables like the age of the person walking on the floor, their physical/mental health, their choice of shoes or their specific gait. All the factors contribute heavily to the overall likelihood that someone might or might not safely traverse an area. Section 302.1 of the current ADA Guidelines (2010) states that “floor and ground surfaces shall be stable, firm, and slip resistant”. It goes on to say, i.e. no loose gravel.