Static Coefficient of Friction for Ceramic Tile

As I noted before, I believe the safety issues to be more a matter of maintenance than product selection. A glass surface can be “safe” if there are no foreign substances on it while a highly textured surface that is not porous may be dangerously slippery if coated with oil or detergent.

The reality is that most surfaces, even very smooth ones, are “slip resistant” if kept reasonably clean and dry. Polished surfaces can be more slippery when wet, but not necessarily more so than textured surfaces. Don’t use smooth surface walking surfaces where they are likely to become wet, typically exterior walkways.

It seems to me that this discussion has been driven by a certain amount of defensive practice in response to predatory lawyers armed with bad science. Before you put this stuff in your specs (and it won’t hurt you), understand what is really going on. The installed material may not prevent a dangerous slip and fall, but good maintenance will.

Peter, I sure agree with you on all that. Hoping to keep clients protected from claims whether they be legitimate, or predatory, or fraudulent. We spec writers can’t control how facility maintenance is done either, that is for sure. We can only give them something reasonably good to start with. I think that is what the A137.1 was trying to say, but they didn’t finish the job in my opinion, and maybe even hung us out to dry when truthfully little to none of this has anything to do with the specifier. So I will raise the issue with designers and have something in the spec as a draft that should protect. I don’t want it to confound the bidders either but it will take Designer of Record or Owner input to change that because this is exactly what the standards dictate for now.

This was the subject of “Excuse me, but your slip is showing!” , published in April of this year.

I offered no solutions, but some of the comments indicated other sources of information.

ADAAG 4.5.1 only requires that accessible routes to be stable, firm, and slip resistant.
Note that it does not require a specific SCOF (Static Coefficient of Friction).
Also the 1991 ADA advisory of 0.6 SCOF on a flat surface and 0.8 SCOF on a ramp was withdrawn in May of 2011.

ASTM International (and CTIOA) retired ASTM C1028 last May, replacing it with ANSI A137.1 Dynamic Coefficient of Friction (DCOF) that Chris was speaking to above.
BTW… ASTM retiring C1028 (and ASTM D2047 no longer being relevant not being a DCOF) looks to have a major impact on industry manufacturers and their reps.

ANSI has been developing their B101 series with their latest being ANSI B101.3-2012, Test Method for Measuring Wet SCOF of Common Hard-Surface Floor Materials.
I’m waiting for the ANSI / NSF issue of B101.5, Standard Guide for Uniform Labeling Method for Identifying the Wet Static Coefficient of Friction (Traction) of Floor Coverings, Floor Coverings with Coatings, and Treated Floor Coverings… to resolve some of this uncertainty for us all.

ASTM also uses ASTM E303 to introduce the internationally recognized British Pendulum Method, also standardized under CSN EN 13036-4, Road and airfield surface characteristics - Test methods - Part 4: Method for measurement of slip/skid resistance of a surface: The pendulum test.

The bottom line is responding to the ADAAG language accessible routes to be stable, firm, and slip resistant.
Whether we specify the use of a British Pendulum Tester, a BOT-3000E Tribometer or a TORTUS II tribometer… the key is establishing what DCOF threshold to use for different surfaces.

There are at least two issues about specifying slip resistance that may be unclear in general:

  1. What are the regulatory requirements - and they may vary by jurisdiction.

  2. How much protection from lawsuits - whether legitimate or not - does the Owner want? (like Jerome mentioned in the initial post)

For the 1st item, there still does seem to be a major lack of specific recommendations in U.S. standards, i.e. it says you might need higher than 0.42 but we’re not going to give you any clues how to decide how much.

For the 2nd item, their maintenance may have the primary effectiveness as long as the material and installation allows for #1 and #2 above also, which is secondary in effectiveness but comes first in the sequence of events.

The only useful help I was able to find, was the Australian implementation of ASTM E303 at the link above (the-worlds-most-sophisticated-floor-slip-resistance-testing-standards). This is from a California-based testing agency who points out that Australian requirements are very detailed for various circumstances. (scroll down at that link for detailed slip resistance values recommended for various circumstances, but using the British pendulum test - which we call ASTM E303.) About ANSI A137.1 they write “Does this system make more sense than a one-size-fits-all minimum such as 0.42 after which the customer must make important decisions based on no advice or data whatsoever? The Australian standard we refer to is a minor revision of one thats been in effect since 1999. We think thats something to hang your hat on when you try to prevent injuries or to defend yourself in court. The pendulum test instrument used in this situation-specific test has been testing floors involved in actual real-world slip and fall accidents in the United Kingdom since the 1950s, so the research into these safety standards are unparalleled with any other instrument or test method. Its used in at least 49 nations on five continents.”

You may say Australian standards cannot be enforced in the U.S. It is actually a long-time British and US standard, they have just gone a step further by providing the detailed recommendations that we lack. About whether or not things are enforceable - Non-codified standards can be and often are specified. That makes them the basis of the bidding, and once awarded then they are the basis of a contract. Construction contracts are enforceable by law unless there is a contract modification. This goes for public and private entities alike. Private Owners may have more leeway to uphold non-codified standards during the pre-contract stage than public Owners do.

It doesn’t help to just go with DCOF 0.42 when it adds a wide-open statement that THE SPECIFIER must go higher than that in many situations without telling us how high. Like William says, just the fact that one standard is updated and this information is available may be usable for defense (or offense) in a legal case. So an Owner my wisely want to enforce a provision for even higher slip and fall avoidance in some circumstances.

DCOF at all is the big shift the last couple years in the U.S. (which can be measured by the British Pendulum Tester, or BOT-3000E, or others) and the U.S. tile manufacturers are all doing BOT-3000E pretty much now, so what does it do to interior designer’s selection of products to add testing few people here are using for their products? That is another issue. Last I checked, specifiers do not control interior designers.

Also, what about other types of flooring? Why is this addressed in guide specs for ceramic tile (albeit poorly due to the standards) and not other surfaces? Is it because tile is harder to fall on? I have seen very high dry coefficient of friction requirements discussed for pro basketball court floors, that is about it.

I’m waiting for the ANSI / NSF issue of B101.5 to address this lack of DCOF standards.

All we can do at this time is to “make an effort” towards compliance with the ADAAG language.

Not making an effort leaves the Owner and A/E open to possible ADA litigation.

Daltile has tried to address some of these concerns. They do have a chart that address specific areas of concern as you mentioned and some other minimum guidelines
Dry and level areas Interior areas no DCOF required
Wet and Level public areas likely to be walked on wet DCOF of 0.42 or greater
Dining areas (front of House) DCOF of 0.50
Ramps, Inclines & Uncovered Exterior DCOF of 0.65 or greater (textured tile required for tile greater than 6 x 6)
Covered Exterior (patios, gazebos, covered walkways) DCOF of 0.60 or greater (textured tile required for tile greater than 3 x 3)
Minimal Footwear in a wet area (public showers, steam rooms, pool decks) DCOF of 0.55 or greater (textured tile required for tile greater than 3 x 3)
Oils (back of house kitchens, food prep, auto areas) DCOF of 0.06 (Textured tile required if a glazed tile is used).

What would would be the problem with simply specifying a requirement of DCOF 0.60 for all floor tile? I find it hard to believe that any floor tile would have difficulty meeting this requirement. If my assumption is correct, this becomes a non-issue. Specify that worst-case value for all floor tile, thereby satisfying the client’s concern that it be stipulated in the documents, and move on.

How do you know the designer will pick a tile that is either 1) already tested to 0.60, or 2) that can pass specially arranged testing?

Or what if they already selected it with no regard for this, and the selection has to be what it is? Then if we specify this way we only introduce a conflict in the documents and no one is any safer.

Maybe for ceramic floor tile but what about the different finish types of resilient flooring, wood flooring, natural & synthetic stone, etc.?

A 0.60 DCOF may not be universal to all conditions of use and many finish types.

It’s why I hope ANSI / NSF issues the B101-5 soon.

Dale, I hunted through Daltile’s site and could not find the data you listed or the table you mentioned. I may try to reach them, it does sound like they are ahead here. I was hoping so since one of their tech guys wrote an article posted by TCNA. So far on their site though I can only find outdated C1028 info, and even in their 3-part spec.

Anon, I think Dale was saying to accomplish a DCOF of 0.60 (I’m pretty sure he transposed the digits accidentally) e.g. for food prep / auto service where you could have greasy spills, those will probably require a textured tile, especially if glazed tile is being used. I doubt the designers or owners are going to want textured tile in places where it is not needed. They will very likely indicate (or have already indicated) basis-of-design products that do not meet the spec requirements. If we just introduce a probable conflict in the documents, that is like kicking the can down the road.

I’m sure Jerome has solved somehow for his project by now but I’m thinking in terms of masters and various project specs because of the wide-ranging effect this has on many projects that have floor tile, until the standards have specific recommendations.

Hi Chris,
I could not find it on Daltiles website either. I do have the chart that the Daltile Reps still hand out and I am told it is still valid. I can scan it and email to you if you like. And yes youre correct that was a typo, thanks for the correction it is DCOF of 0.60 for back of house.

Anon, a universal 0.60 DCOF would eliminate 60% to 80% (guesstimate) of all tiles. Probably 80% of all tiles would meet the 0.42 DCOF Most of your floor tiles are manufactured to meet that standard. Tiles manufactured to meet or exceed the 0.60 DCOF has to have an aggressive texture to meet that requirement. With that type of finish it will also be more difficult to maintain due to the texture on the surface of the tile.

How do you know the designer will pick a tile that is either 1) already tested to 0.60, or 2) that can pass specially arranged testing?

Or what if they already selected it with no regard for this, and the selection has to be what it is? Then if we specify this way we only introduce a conflict in the documents and no one is any safer.

Has anyone worked with any of the clear, penetrating sealers that claim to impart various levels of slip-resistance?

I’ve been inundated in the past by folks like Miracle Sealant (https://miraclesealants.com/msds/s_tile_stone_sealer_msds.pdf) and Slip Doctors (http://www.slipdoctors.com/products-msds.asp). I’ve used Miracle Sealant as a last resort on a couple of stone projects in building lobbies and had good results. It didn’t change the appearance of the stone during the time I was checking it but I never went back to see what the long-term effects were after enduring years of maintenance. Anyone else ever use these sorts of products. There are other manufacturers as well. I think Hillyard used to make something similar for wood floors. Vexcon makes one for polished concrete.