When shopping for tile, published slip resistance ratings help you determine if you're buying the right tile for the right location. Other types of floor coverings may have such ratings, but usually not.
Unless you work in a lab, engineering office, or academic setting, the last time you used the word "coefficient" was back in high school math. But if you're shopping for flooring for your home, "coefficient" (as in Coefficient of Friction, or COF) is one of the most important words you can consider.
COF ratings are becoming more important as consumers buy their flooring sight-unseen from online outlets.
3 Things You Would Never Guess About Slips and Falls
Slippage is a huge concern with any type of flooring. Minor slips can have a domino effect that lead to disastrous results. Add moisture from bathrooms and kitchens, and even that seemingly slip-free floor can feel like an ice skating rink.
Most people's eyes glaze over when you mention home safety. But some of the following statistics may surprise you.
- Slips and falls are the second-leading cause of unintentional fatalities in the home, according to the National Safety Council.
- Actually, not all of these falls are related to flooring. People can fall for any number of reasons--loose cords, large obstructions, inattention, physical disabilities, etc. It is also important to note that, within the area of floor-related injuries, only some are related to how slippery the floor is.
- Still, the National Floor Safety Institute says that 2 million fall injuries per year are attributable directly to floors and other flooring materials. Most fall injuries happen on the ground floor, not an elevation.
Slippery As Glass?
Coefficient of Friction ratings are mainly applied to tile flooring, and it is just another way of saying, "How slippery is this tile?"
To see how important this question is, look at one extreme. Natural stone can be polished and honed until it becomes as slippery as glass. Slippery window glass obviously has no bearing on safety because it is vertical and no one will ever walk on it. Slippery floor glass, if such a thing existed, would be dangerous because shoes plus water plus motion equal a nearly 100% chance of slippage.
Yet stone and even some ceramics and porcelains can reach glass-like slipperiness. That's why large commercial and public buildings with highly polished granite floors lay down mats at the first drop of rain.
It's Not Guesswork: It's Science!
Tile companies voluntarily subject their products to testing at independent laboratories which measure skid resistance. Tests have evolved over the years, and the current test, DCOF AcuTest, developed by the Tile Council of North America, is intended to replicate real-world conditions more than did the older tests. The older test measured both static and dynamic skid resistance; the current test measures only dynamic skid resistance.
Static resistance means how much force is required to start two stationary surfaces moving against each other. Example: a person standing stationary on a sloped floor.
Dynamic resistance means how much force is required to keep two already-moving surfaces moving. Example: a person walking onto a surface--in motion--and stepping onto the tile.
Higher numbers mean more traction. Lower numbers mean more slippery.
DCOF vs. COF: Don't Be Fooled
According to the ANSI A137.1–2012 standard, ceramic tiles selected for level interior spaces expected to be walked upon when wet must have a minimum wet DCOF AcuTest value of 0.42.
- The Tile Council of North America
Numbers can be deceptive, as some tile manufacturers still publish older ratings.
- Wrong: A manufacturer says that its tiles are rated at "≥ 0.60 wet." Because it is specified as the earlier SCOF rating, the tile is still reporting earlier guidelines for safety.
- Right: A manufacturer says that its tiles are rated at "≥ 0.42 wet." Because this is specified as the DCOF AcuTest, its wet ratings are using the current system.
This doesn't mean that "≥ 0.60 wet" tiles are unsafe. It only means that they are up to spec to the earlier system.
In fact, none of these ratings--current or past--address safety. They only list results of scientific testing, and let you derive meaning from them.
What About Other Types of Flooring?
If you're buying tile, you're in luck. With other types of flooring, you may not be able to research slip ratings.
Dallas-based lawyer Russell J. Kendzior is a leading expert in slip-and-fall injuries. His National Flooring Safety Institute is the go-to place for information about flooring-related injuries Kendzior says that, except for tile manufacturers, the floor covering industry has refused to test for slip resistance and even create a set of testing guidelines.
Accidental omission? No, Kendzior states that this omission is quite intentional. In Attorney-At-Law Magazine, he states
Floor covering manufacturers see slips and falls as a minefield of liability and avoid discussing the subject publicly. As they see it by not adopting a COF safety standard means that if they are sued, the plaintiff can’t hold them to a standard that in their view doesn’t exist!
Flooring companies may privately test for COF, but most feel no compulsion to publish these ratings.
In one case, this may be warranted. Unfinished flooring (such as solid hardwood) is site-finished. Thus, skid resistance is up to the owner since the finishing process is also up to the owner.
Laminate flooring is a different matter, since it is factory-finished. In a few cases, the manufacturer may publish these ratings.
For example, DuChateau's European White Oak laminate flooring has a COF (not DCOF) of Static 0.59 and Sliding (or Dynamic) 0.43. Armstrong Architectural Remnants Coastal Living Patina Rustics Premium Static-Rated at > 0.50.
What To Do
The best advice is to ask the flooring retailer if COF ratings do exist for the laminate, luxury vinyl, conventional vinyl, or any other type of floor covering you intend to purchase.
They may have ratings on hand that you cannot find online.
For tile, research DCOF ratings. If none are available, then that may help you influence your tile purchase.