Paving slab anti slip ratings: what the R ratings means

When buying a particular kind of paving slab or floor tile, it will sometimes have an anti-slip rating listed under its key features. It may say it has an R11 or R12 slip rating, but without context or explanation these ratings leave potential buyers in the dark. This article seeks to explain the slip ratings, so buyers have an understanding of what the different ratings mean.

How slip resistance ratings are determined:

A simple test is carried out to determine the slip resistance of a surface. The tester wears rubber soled shoes or bare feet and walks up and down the surface which has been lubricated. The platform underneath is gradually angled and when the tester slips, the angle is recorded.

Each rating is based on a range of angles, as you’ll see below:

This is the lowest slip rating. Flooring with this rating will generally have a smooth, glossy surface which will likely become slippery when wet. They are mostly found indoors rather than outdoors, and care should be taken when walking on them.

In testing, R9 flooring is designated when a tester can walk comfortably on it between 3° and 10°.

This rating often has a matte surface, with enough structure to keep shoes from slipping on them. R10 rated surfaces are used indoors and outdoors where there is minimal water exposure. They may be found in toilets, kitchens and commercial food areas.

In testing, R10 is designated between the angles of 10° and 19°

Outdoor paving and indoor flooring with this rating is designed to be used in areas which likely have greater exposure to water. The surfaces will likely be textured so that shoes will not slip. For this reason, this kind of flooring in settings that are likely to be exposed to high levels of water, such as wet rooms, patios and open terraces.

R11 is assumed to be the standard anti-slip rating for exterior paving tiles in the UK, where wet weather is assumed!

R11 is designated when the tester can comfortably walk on a platform between 19° and 27°.

This rating is often found on surfaces which are selected for industrial settings and areas that are very likely to be inundated with water. They sometimes have channels or recesses set into them to allow water to easily run off and are textured to offer greater friction than lower ratings.

This rating is applied when the tester can continue to walk on the surface when it is angled between 27° and 35°.

This is the highest rating available and has an extremely high degree of static friction (the kind which ensures you can apply downwards pressure and continue moving forward). They often have recesses which allow for water and liquid drainage, and are very useful for industrial settings like factory floors and automotive manufacturing plants. They can also be found around spas and public swimming pools.

R13 is designated when a tester can walk on the surface if it is angled at 35° and above.

How does slip-resistant paving work?

The act of walking or running requires friction. Water and moisture in general reduces the amount of friction on a surface, which means those who are walking on it can no longer exert the downwards force needed to travel. It should come as no surprise, then, to find that many commercial uses of slip-resistant paving are in areas of high moisture., such as public swimming pools.

Anti-slip paving is also useful in settings that require heavy lifting. An industrial warehouse which requires the movement of bulky items is a good example. Those workers moving the heavy items will be exerting greater downward pressure on the floor beneath, requiring higher amounts of friction. Here, a high slip-resistant rating will ensure greater safety.