This summer my husband and I went to a Caribbean island for a little R&R. This gorgeous and brand new facility was one of those fantastic all-inclusive resorts you see all over the Caribbean now and we had a great time, a little slipping notwithstanding.
Trotting around the pool on the beautiful tiles they had with imprints of shells and fossils, I hit a wet spot on an incline outside the bathroom and went down! Whoops! In the process I sprained my left pinky toe so it was purple by the following morning; no beach volleyball for me! This was a minor dent in my vacation, but is a great example of why areas prone to standing water and wetness (especially in our litigation-prone society) require slip resistant tiles.
2010 ADA Standards for Accessible Design (ADA stands for the Americans with Disabilities Act, which is NOT applicable in our neighboring small Spanish-speaking islands) states in 302.1 that “Floor and ground surfaces shall be stable, firm, and slip resistant” and “A slip resistant surface provides sufficient frictional counterforce to the forces exerted in walking to permit safe ambulation.” (Yes, Interior Designers have to be able to read “Legalese” as it is written into Building Codes and Guidelines.)
Most often meeting this requirement means checking what is called Coefficient of Friction (COF) of the flooring. COF is a number on a zero 10 one scale that is the result of one of several possible tests, most commonly performed for ceramic and porcelain tiles. The metric is presented as a decimal number less than 1 and generally above 0.5 is considered slip resistant enough for most general code. ADA, however is a little more stringent and generally desires 0.6 for flat surfaces and 0.8 for ramps.
Its also important to note the condition of the test. In the last few years, the Tile Council of North America has made this testing program more rigorous by separating results into Wet or Dry, Dynamic or Static COFs to differentiate between testing conditions. A Dry/Static COF is always higher than its Wet/Dynamic counterpart and if you only have one listed (which is becoming more rare) assume it’s dry and consider how wet the space is likely to get before deciding that your COF is good enough.
After my slip I went on with my vacation, my toe a reminder of the importance Americans place on safety over beauty. Or I could be cynical a say the importance Americans place on avoiding legal ramifications. Either way, it reminded me of standards that architects and designers in the US are held to that other countries don’t enforce (and vice versa: many European countries have codes that workspaces be no more than X distance from a window. This requires that no one work in a windowless underbelly of a sprawling 40+ year old monstrosity). For good or bad, knowing the Coefficient of Friction of the tile going in your new bathroom just might be important to you. It will be important on my next project!