When assessing the suitability of the slip-resistance of a floor finish in the UK, we are often faced with a variety of standards, ratings and test methods, not to mention an array of acronyms. But which one is the most reliable? In this article, we take a look at four of the main scales of slip-resistance currently used, which one to employ in which situation, and how they compare against each other.
Image: Courtesy of Altro Floors Ltd
‘R’ Rating
One of the most widely used CoF (Coefficient of Friction) tests in the UK for slip-resistance in floor coverings is the ‘R’ Rating. This is a Ramp Test (hence the R), and is performed by testing the floor finish at various inclines. In spite of its popularity, however, the Ramp Test is not recognised by either the HSE or British Standards, but is covered by the European standard DIN 51330. It is also a very broad and limited indication of the true slip-resistance of a floor, with only five rating levels (R9 – R13). Furthermore, unlike other methods of testing for slip-resistance, it isn’t portable, so cannot easily be undertaken in-situ, or on site. The following represent the inclines tested to determine a floor coverings ‘R’ Rating;
R9 - Between 3 and 10 degrees
R10 - Between 11 and 19 degrees
R11 - Between 20 and 27 degrees
R12 - Between 28 and 35 degrees
R13 - 36 degrees or more
Pendulum Test
The Pendulum Test is also a CoF (Coefficient of Friction) test, and is carried out by a specialist pendulum testing machine to simulate either a shoe or bare foot on a surface, resulting in a Pendulum Test Value, or PTV. This gauge of slip-resistance is widely used in the UK, and an approved method of measurement by both British Standards (BS 7976-2:2002) and the HSE. PTV values range from 0 (least slip-resistant) to 70+ (most slip-resistant), and testing apparatus are usually portable, allowing for in-situ and on site testing. The most common standard test method to obtain a PTV is the wet test – using a 4S Rubber and 96 Slider.
ABC Rating
Often used to indicate a general slip-resistance in flooring, the ABC Rating is actually designed purely for barefoot use, and is carried out as such, using soap-like lubrication of the sub-floor. This method of testing for slip-resistance can be applied to any floor finish, but is most widely used for ceramic and porcelain tiles. It is perhaps the broadest test of its kind, offering only three rating levels, A, B & C, with A being the least slip-resistant, and C being the most.
Surface Micro Roughness
Another lesser-used but HSE approved method of testing slip-resistance in flooring is the Surface Micro Roughness test, returning a Rz value. The meters used to determine this attribute are typically used by engineers for alternative methods, but will generally return a roughness unit in μm. Advantages of this method include meters being portable, but disadvantages include it not being widely recognised, and purely representing the roughness of the material only, whilst failing to incorporate contaminants or site conditions.
We have put together the table below to illustrate an approximate comparison between the four methods of testing slip-resistance in a floor finish mentioned above. Please note that this is a guide only, and final selection of flooring needs to incorporate whether areas are likely to be wet or dry, are heated all year round, the maintenance schedule, types of user, and many other factors. For specific projects, please feel free to get in touch with your exact requirements.
