Considering the slip resistance of flooring
The HSE states that a third of all reported major accidents are due to slip and trips where 40% involve members of the public. Statistically, most of these are slips occur when floors are contaminated. Common contaminants are often water, oil and grease and talcum powder. Solutions to slips and trips accidents, however, are often simple and inexpensive to implement.
Causes of slips
The Health and Safety Laboratory (HSL) has developed a slip potential model which shows that a combination of aspects will contribute to slip accidents.
- Floor type: flooring types have different characteristics, all of which will have different slip resistant properties.
- Contamination: foreign bodies can affect the profile and performance of a floor and increase the risk of slipping.
- Cleaning regimes: apart from poor cleaning which can leave residue behind on floors, cleaning in its nature will leave floors wet and potentially slippery.
- Environmental factors: adverse weather will have negative effects on flooring from rain, snow, loose leaves and debris, mud or even freezing temperatures.
- Footwear: the type of footwear worn can have a contributing factor in slipping accidents.
- Usage: flooring in heavily-used areas can either have negative affects by either smoothing out during wear or positive, if it contains gritty particles which become exposed during wear.
- Human factors: lack of attention can be a contributory factor in slip accidents.
The Workplace (Health, Safety and Welfare) Regulations 1992 requires floors to be suitable, in good condition and free from obstructions. No two floor types are the same. Different floors have unique characteristics with their own properties which will be the deciding factor on their performance with regards to slip resistance over time. Slip resistance potential of a floor is defined by:
- What kind of surface finish it has
- How the floor wears down over time
- How easy it is to clean.
There is a misconception that profiled floors offer good slip resistance. However, profiled floors can have a smooth finish that when wet will be extremely slippery.
Slip resistance potential can be modified with some floor types. This can be done by mechanical modification, using grinders or by shot blasting. There are many anti-slip products that can be used to increase the slip-resistance of floors ranging from anti-slip paint, stair nosings and anti-slip tapes. If intervention is used, the life span and costs should be considered with the modification as with wear over time the flooring will naturally go back to its original form. The behaviour of the floor is very much dependent on its location and usage.
Assessing slip resistance
HSL has developed a reliable and robust method of assessing slip resistance of flooring. The methodology comes in two parts:
- Measurement using a Pendulum Coefficient Friction Test.
- Surface Micro Roughness Measurement.
Pendulum Coefficient Friction Test
This test is regarded by the HSE as the most reliable and accurate form of slip testing of flooring in both dry and wet conditions. The test is based on imitating the swing of a heel using a standardised rubber sole. The pendulum test value (PTV) given is a direct and measurable test of a floors slipperiness. The devise is swung over a set area in the direction of flow of traffic, at 45o, and at 90o to the flow of traffic and an average is taken of the readings. The test is subject to British Standard BS7976:Part1-3, 2002 and should be only carried out by a trained competent person.
There are other commercially available slip resistance tests which are sled test based, like the TORTUS or the FSC2000. They are not accepted by the HSE as a true indication of slipperiness, as the test can only be carried out in dry conditions and as such does not indicate the true slip resistance on contaminated floors. Also, these slip tests do not re-create the condition of a pedestrian walking, which is when usually slip accidents happen.
Surface Microroughness Measurement
This test is a simple measurement of the roughness of the flooring used to supplement the pendulum test. The Rz value is a calculation of the total surface roughness by measuring the peaks and valleys of the floor’s surface. It is simple to use and anyone can take the measurement, which can be used to monitor the changes in the floors surface profile due to wear, or can be used as an indication of slipperiness in water-contaminated surfaces. The higher the Rz value the more rougher the surface and greater potential of slip resistance.
Slips Assessment Tool
The HSE and HSL have produced the Slips Assessment Tool (SAT), a PC-based software that is free to download from the HSE website. SAT can be used to assess the risk of slipping of pedestrian walkway surfaces by entering the data received from a surface micro-roughness when a pendulum is not available. The tool prompts the user for further data on the condition of the surface, regimes used for cleaning, likely footwear worn along with human and environmental factors to provide a slip risk classification. It does not account for performance of a floor but can be used for decision making by assessing the potential risk between various scenario conditions and cleaning regimes.
Floor contamination and cleaning regimes
One common denominator in all slip accidents is the presence of contamination. Even a small spill can pose a risk. Keeping floors clean is vital and if the cleaning is poorly done, it can pose further risk.
Certain facts regarding cleaning should be noted.
- Clean, dry, smooth floors rarely pose a slip risk.
- A well-wrung mop will still leave wet residue on a floor, which increases risk.
- Dirty, greasy mops will only spread contamination around
- Mopping alone will not be effective against profile or rough floors; manual or mechanical brushing is needed.
- Putting a warning cone or sign up to show that a floor is wet is not enough to stop people from slipping.
People slip due to lack of adequate housekeeping and when floors are in poor condition. They rarely injure themselves on good, clean, dry floors. To manage the risk from slipping, some of the following practices can be adopted.
- Management systems: assess the type of cleaning used and when the cleaning is to be carried out: communicate the details to others.
- Risk assessment: assess your flooring with regards to the likely risks when contaminated and monitor the floor on a regular basis, particularly in high usage areas.
- Contamination control: prevent slips on flooring close to entrances by placing matting to trap contaminants; be diligent in removing any spills as soon as possible.
- Floor repair: repair damaged floors as soon as possible with like-for-like material so that the repair has the same slip resistance properties as the rest of the floor.
- Remove obstructions: Keep walkways clear; good housekeeping should always be a primary focus.