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Skid Resistance Scales for Tile Flooring

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Skid resistance scales are used to determine the degree of slippage on a tiled surface. While assessing different tile surfaces, wet and dry conditions along with the speed of the subject are monitored. Also, the required force to move that subject and the angle of the tiled surface are considered too. The Ceramic Tile Institute identifies tile in the following three categories:

  1. Slip Resistant: Coefficient of friction is 0.60 or greater (wet). Meets or exceeds general safety and health regulations, ADA and OSHA requirements.
  2. Conditionally Slip Resistant: Coefficient of friction is 0.50 to 0.59 (wet). Meets or exceed general safety and health regulations and OSHA requirements.
  3. Questionable: Coefficient of friction less than 0.50

One important thing to note is that the more textured a tile is, the less slippery it is. This is why polished or highly polished tiles are not recommended for high traffic areas or for residential sites with children and elderly people. As a rule though, the greater the anti-slip finish on the tile, the harder it is to keep clean.


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Another set of information used to determine resistance is the DIN (German Institute for Standardization) classification for tile slippage. One of the methods this system uses is the DIN 51130 set “ramp test”. In this set, various surfaces are rated in one of five groups according to their degree of slippage. To determine which of these groups a material should be classified in, operators apply it on a surface that is gradually sloped and then spray it with motor oil. A person wearing shoes walks up and down the slope until they start slipping. The value in degrees of the slope reached before they start slipping determines the classification of the material in class. Here are the ratings:

  • Rating R9 – Suitable for a less than 10° slope (minimal friction)
  • Rating R10 – Suitable for a 10° to 19° slope (normal friction)
  • Rating R11 – Suitable for a 19° to 27° slope (normal friction)
  • Rating R12 – Suitable for a 27° to 35° slope (high friction)
  • Rating R13 – Suitable for slopes more than 35° (very high friction)

Also, another DIN 51097 set classifies tiles from A to C for non-slip suitability. This test uses a soap solution instead of motor oil and participants are barefoot:

  • Rating A – Suitable for slopes 12° to 17°
  • Rating B – Suitable for slopes 18° to 23°
  • Rating C – Suitable for slopes >24°

There is also the Pendulum Skid Resistance Test, which gives the following ratings for tiles:

  • Rating <25 – Very slippery
  • Rating 26-35 – Average
  • Rating 35-65 – Good skid resistance
  • Rating 66+ – Excellent skid resistance

When shopping for a new tile floor, look at the technical specifications provided and whether or not the surface is polished to determine the surface’s slip resistance. If you’re unsure what would be best for your space, talk to a knowledgeable BuildDirect Product Expert or a professional installer.

How much slip resistance do you need for your tile flooring project?

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(9) Comments

  1. I want to use a polished marble in 12×24 pieces on a master bathroom floor. Would you recommend this and what is the slip coefficient of Marble?

    How does the slip coefficient change with a mosaic marble pattern with a lot of grout lines please?

    Thank you

    • BuildDirect Product Expert Team
      BuildDirect Product Expert Team - Reply

      Hi Nancy,

      Thank you for getting in touch! The coefficient of friction is only used on porcelain tile, not for natural stone. A polished porcelain tile will have a coefficient of friction of about Wet: >0.6; Dry: >0.7 and it will be similar for the marble with a polished finish. Using a mosaic with more grout around will make it less slippery. You can also look into a type of sealant that adds extra grip to the surface. Please let us know if you have any other questions!

  2. Jerome D. Paulick - Reply

    I am inquiring about the coefficient of friction (COF), dry or wet, of your discontinued glazed porcelain tile, Pastorelli Tile Tri-B Technostone, 12”x12” color Kanrak and Menfi sold and installed in the USA. Is a specification data sheet giving COF information available for this product? Let me know and thank you for your time.

    • BuildDirect Product Expert Team
      BuildDirect Product Expert Team - Reply

      Hi Jerome,

      Thank you for getting in touch! Unfortunately we haven’t carried any Pastorelli tiles in the past so I’m not able to provide the COF information for you. We did have a Piastrella brand, is that what you meant? I searched Pastorelli and found the link below, you may be able to get in touch with them to see if they have the specification sheets for you.


      Please let us know if you have any other questions!

    • BuildDirect Product Expert Team
      BuildDirect Product Expert Team - Reply

      Hi Alexander,

      Thank you for your inquiry! Unfortunately we have not heard of an “NDP” rating for tile. The industry standard is usually the Coefficient of Friction or, more recently, the Dynamic Coefficient of Friction. That may be a new measurement that a brand is starting to use. Please let us know if you have any other questions!

  3. Thanks for the comments on slip resistance. I am looking for slip resistant tile from porcelain or stone for an inside pool deck. Can you help? Thanks.


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