What is DCOF Rating?

Featured Image: Faro Beige 12 x 24 Porcelain Floor Tile from Arizona Tile

You may have seen references to DCOF ratings in the product testing data when purchasing tile, but what is it?  This may be a question that comes up from time-to-time, but we’ll help clarify what it is and when it might be helpful to ask.

Since 2018, the preferred measurement for a surface’s slickness has been Dynamic Coefficient of Friction, or DCOF. This rating is measured with specialized equipment using a standardized testing method laid out by the American National Standards Institute (ANSI) and Tile Council of North America (TCNA).

So, what does a tile DCOF rating mean? Let’s break it down and find out!

Understanding Dynamic Coefficient of Friction

We’ll start by dipping our toes into physics for just a moment here. According to the definition provided by the TNCA, the Coefficient of Friction (COF) is a measurement determined by the ratio of friction resisting movement of two surfaces in contact.

In layman’s terms, COF is a measure of traction; how difficult it is to move two surfaces that are touching each other. Keep in mind that this is a material property of two surfaces: the flooring, and the surface placed on it, like the sole of a shoe or a bare foot.

Image: Icon Smoke Hex 20 x 24 Porcelain Living Room Floor Tile from Arizona Tile

Dynamic Coefficient of Friction, then, is the measurement of two contacting objects already in motion. The higher the coefficient of friction, the harder it is to continue the motion of the object. Want to know how slick that new kitchen floor will be? DCOF is used as the standard rating for indoor applications in North America for how slippery tile is when wet!

How are DCOF ratings measured?

Image: Shibusa Crema  24 x 48 Living Room Floor Tile from Arizona Tile

Dynamic Coefficient of Friction is a benchmark measurement and can be incredibly useful for manufacturers, retailers, shoppers, and contractors alike. DCOF is represented as a decimal between 0.01 and 1.0, with higher decimals representing a higher rate of traction.

While no tile option can be entirely slip-proof, a tile with a DCOF rating of ≥0.42 is considered safe to use in both residential and commercial settings. It should also be noted that all of Arizona Tile’s standard finish porcelain tile series meet the standard rating of ≥0.42.

The standard DCOF testing method is a “wet test.” The surface to be measured is coated with a solution of slightly soapy water to simulate ideal slip conditions. A measuring device then crawls along a programmed path using a small set of wheels on its undercarriage, swinging its rubber sensor or “testfoot” to measure resistance. This process is repeated multiple times at different angles and then averaged to calculate the DCOF measurement.

When should you ask about DCOF?

Image: Lagos Sand 24 x 48 Porcelain Bathroom Floor Tile from Arizona Tile

Dynamic Coefficient of Friction testing isn’t a code requirement for household projects, only for commercial use. Unless you’re flooring a mall or a spa, it’s likely just something that’s good to know about your tile. It’s also important to mention that DCOF is an indoor test only. It does not apply for outdoor applications.

DCOF is still important, though, because it helps to ensure public safety. A DCOF value lets us know how likely it is for someone to slip and fall on a given surface. High DCOF values mean that the material is less likely to cause a slip and fall, while low DCOF values indicate a greater risk. Since there are a lot of variables that go into each slip (shoe grip, spill slickness, tile wear, etc.), it’s impossible to call any material “slip-proof.” DCOF works best as a comparative measurement, not a perfect predictor.

Image: Konkrete Beige  24 x 48 R11 Anti-Slip Finish Porcelain Patio Tile

Still have questions? Contact us and one of our experienced associates will help to answer any questions you have. Feel free to stop by one of our locations to explore our extensive stone and tile collection. Or  for a more visual experience without leaving your home, check out our virtual slabyard or Just Imagine Visualizer.