Understanding Porcelain Tile Ratings

Two of the questions we hear all the time are, “What is the DCOF or PEI of this Italian tile?”, and
when they find out that European standards are measured differently, they follow up with, 
“What is R11?” The answer is that they all measure different things, and understanding the 
difference helps you choose the right tile for the right application.
An R11 rating is a European slip-resistance classification that measures how much grip a tile 
provides under wet conditions and the method they use to test it is with an inclined ramp test. 
R11 falls into the high-slip-resistance category, making it an excellent choice for outdoor patios, 
pool decks, walkways, entryways, and other areas exposed to pool water, rain, or moisture. It’s 
designed to give you added confidence underfoot when surfaces become wet. 
In the United States, you’ll more commonly see a DCOF (Dynamic Coefficient of Friction) rating
on specification sheets. While the testing methods are completely different, they both evaluate 
slip resistance. A DCOF of 0.42 or higher is generally recommended for level interior areas that 
may become wet. Many exterior R11 porcelains often exceed that minimum because they’re 
engineered for even greater traction outdoors. 
A PEI rating, however, measures something entirely different. PEI evaluates a glazed tile’s 
resistance to surface wear and abrasion, not how slippery it is. In essence, PEI tells you how 
well a tile will hold up to foot traffic, while R11 and DCOF tell you how much grip it provides.
Can an R11 tile be installed indoors, too? Absolutely. In fact, they’re commonly used in 
commercial kitchens, spa areas, locker rooms, and shower floors where maximum slip 
resistance is needed. However, for most residential interior floors, they may not be the best 
choice.
This is because R11 porcelain has a much more textured surface, and it really grabs onto dirt, 
dust, and debris more than a smoother interior tile. We call it grippy and its hard to clean. 
Outdoors, that’s rarely an issue because rain and occasional pressure washing make 
maintenance easy. Inside your home, however, you can’t simply pull out a pressure washer in 
the living room. While regular mopping works, the textured surface generally requires more 
frequent and more thorough cleaning to keep it looking its best.
For most homeowners, the ideal solution is simple: choose a smoother porcelain for your 
interior spaces and reserve R11 porcelain for the outdoors, where its superior grip truly shines. 
That way you’ll enjoy a great balance of safety, beauty, and easy maintenance.