FAQs

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• All our floors are internal, clean and dry, why do I need a slip test?

  Whilst slips are unlikely on clean and dry surfaces, they can still occur and you can still find yourself the subject of a costly compensation claim. Fraudulent slip claims can and are made regardless of surface. As compensation claims are typically brought to court around 3 years after the accident a record of safe floors is imperative if a successful defence is to be made.
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  Ultimately it is rare that clean and dry floors will fail to provide a safe level of grip, maintaining floors in this condition is the best way to prevent slips.

• How can I obtain a PTV for a product?

  The UKSRG members can provide expert independent test reports, showing the Pendulum Test Value (PTV) for floor surfaces, either in situ or in house, as part of a risk assessment, product specification or forensic investigation. To find a contact go to Find a Member and select the filter Slip Testing (Pendulum).

• I have a PTV/SRV value from a product specific British Standard test, is this the same as a BS 7976 PTV?

  Probably, but not necessarily. Whilst the Pendulum will act in the same way on all floor surfaces tested, different methods can involve different rubber sliders or contamination, which may or may not be representative of end use. For most floors you should seek wet PTV’s >35 using the 4S/#96 rubber, for barefoot areas seek wet PTV’s >35 using TRL/#55 rubber. If you are unsure send us a small (300x300mm) sample which we can test in house quickly and inexpensively, providing an independent BS 7976-2 slip test report.

• Does an R9/R10/R11/R12/R13 value equate to a PTV?

  No. The difference in methods means that it is impossible to correlate DIN 51130 R values and BS 7976 PTV’s beyond, “A higher R value will usually mean a higher PTV”. The best way to determine a PTV for a surface with a given R value is to send us a small (300x300mm) sample which we can test in house quickly and inexpensively, providing an independent BS 7976-2 slip test report.

  The DIN 51130 R value is generated using a test operator clad in safety footwear and oil as a contaminant. The BS 7976 Pendulum uses a smooth 4S (Standard Simulated Shoe Sole) rubber and less viscous water contamination. Ramp tests conducted using identical smooth 4S soles and water contamination (as per the HSE/HSL ramp test) show good correlation with Pendulum tests, as could be expected. However, the increased viscosity of oil contamination will serve to effectively reduce available grip, recorded CoDF and equivalent PTV, by an unknown amount. Conversely, the profiled safety footwear will serve to effectively increase available grip, recorded CoDF and equivalent PTV, again by an unknown amount.

  It is a common mistake to assume that each floor surface has a CoDF (Coefficient of Dynamic Friction), ultimately describing how slippery it is, and indeed some websites offering advice on slip testing erroneously equate R values to PTV’s. CoDF describes the interaction between 2 specific surfaces however, and is further complicated by the inclusion of a lubricating film and, for the purposes of slip risk assessment, the biomechanical actions of a pedestrian losing balance. CoDF values produced by differing methods cannot generally be considered interchangeable as a result.
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  It should be noted, when specifying floors, that any slip and fall accident is likely to be followed with a BS 7976-2 Pendulum test to determine if the surface is safe or slippery. On this basis the DIN 51130 R values should only be considered as a specified slip resistance for those surfaces which will be subject to highly viscous contamination and safety footwear in end use. The BS 7976-2 Pendulum remains the preferred slip test method of both the HSE and the UK Slip Resistance Group.

• Which slip test method is most appropriate?

  Ultimately there are very few scenarios where the BS 7976 Pendulum operated to the latest UKSRG Guidelines will not provide the most appropriate measure of slip resistance.

  The BS 7976-2 Pendulum test is the preferred in situ test of both the UK Health and Safety Executive and the UK Slip Resistance Group, and is the test which will be commissioned by an investigating solicitor or forensic engineer in a slip and fall injury case. Given that the purpose of slip testing is ultimately to demonstrate a safe surface and duty of care it would be folly to use test methods other than those which would be conducted for the Court. Whilst the cost of slip testing is bound to influence decisions made, we are of the firm opinion that if tests conducted will not stand up to the scrutiny of a Court and opposing expert witness they are of next to no value.

  Whilst we are aware of several alternative proprietary slip test methods, with various claims of accuracy and ease of use, we continue to employ the Pendulum for risk assessment and product specification in an identical manner to the assessments that we provide to the Court. We would urge you to do the same in order to provide a robust defence should the unfortunate occur.

  There are instances where the BS 7976-2 Pendulum test cannot be conducted; steep slopes, heavily profiled floors, narrow stairs, and cushioned floors. Where the same floor is laid in adjacent areas more receptive to Pendulum testing we would normally conduct tests on this floor and tie the two floors together with measurement of the Rz surface roughness parameter.
  Heavily profiled or cushioned floors are unlikely to pose any real slip risk, however a ramp test replicating the expected footwear and contamination of end use would likely provide a more accurate measure of slip resistance than a Pendulum test.

  DIN 51130 and DIN 51097 may produce meaningful data for industrial and wet leisure environments respectively; however they cannot be conducted in situ, are not thought to be any more accurate than the Pendulum and are typically significantly more expensive than a Pendulum test.

• What is surface roughness Rz testing?

  The roughness of a surface has a significant impact on its contaminated slip resistance. It is a similar mechanic to that which affects slick versus grooved tyres. The Rz parameter is one of many roughness parameters used to describe surface micro-profile.

  Roughness meters can be bought relatively cheaply and do not require an experienced operator, so they see considerable use as a ‘quick and easy’ measure of slip resistance. They should not be considered a slip test method in their own right however. Our own experience has shown the Rz parameter to be an extremely unreliable indicator of slip risk. The result of an erroneously classified floor may be a slip and fall claim or unnecessary replacement of the floor, both expensive ventures justifying a more accurate and reliable Pendulum test.

  The Rz parameter is a measure of the average height between the peaks and troughs of a profile and is typically quoted in microns. A greater Rz value indicates a greater peak to trough height, however it is commonly, and erroneously in our opinion, thought to indicate a greater wet slip resistance. The limitation of this parameter is that a surface with a single discrete rounded peak can produce an identical Rz value to a surface with multiple sharp peaks of the same height, with the latter offering a significantly better wet slip resistance.

  Other roughness parameters include Ra (roughness average), Rq (Root mean square roughness), Rt or Ry (maximum profile height), Rv or Rm (Maximum trough depth), Rp (maximum peak height), Rpm (average maximum profile peak height), Rmax (maximum roughness depth), Rc (mean height of profile irregularities); however these are used primarily in engineering applications as opposed to slip resistance measurement.

• What is DIN51130 DIN51097 ramp testing?

  Ramp testing is a slip test method employed primarily at the product specification stage as it requires a sample of the test floor and cannot be conducted in situ. The subject floor is mounted to a plate on which a (lucky!) operative performs a standardised walk. The floor is lubricated and slowly inclined until the operative slips. The angle at which the operative slips forms the basis of the classification.

  The differences between ramp test methods DIN 51130 and DIN 51097 come from the differing footwear and lubrication types. DIN 51130 utilises safety footwear and oil contamination whereas DIN 51097 utilises bare feet and soapy contamination. It is important to note that these, albeit subtle, differences have a significant impact on the relevance of the classifications to end use.

  DIN 51130 testing produces ‘R’ values ranging from R9 to R13; R13 is the most slip resistant. This method is often used to specify floors in shopping centres, transport terminals, hotels, schools, etc, a wholly inappropriate specification given that such environments are unlikely to ever experience safety boots and oil. We have seen many floors fail to provide safe levels of grip in end use as a result of this. BS 7976-2 Pendulum testing is the method that will be used to determine whether a floor is safe or slippery following a slip, so it makes sense to use the same method to specify floors in the first place. We can provide BS 7976-2 Pendulum test results for a fraction of the price of DIN 51130 ramp testing.

  DIN 51097 testing produces a classification of A, B or C, C being the most slip resistant. This method covers contamination and soles more likely to be found in end use, particularly in wet leisure environments. Typically a DIN 51097 rating of C will produce a ‘low risk of slip’ classification when assessed using the in-situ BS 7976-2 Pendulum test. Again, we can provide BS 7976-2 Pendulum test results for a fraction of the price of DIN 51097 ramp testing, and it is the BS 7976-2 Pendulum that will be used to determine the floor’s suitability in a slip and fall claim.

• What is BS 7976 Pendulum floor slip testing?

  BS 7976 describes the specification, testing and calibration of the Pendulum floor slip test device. BS 7976-2 is widely recognised as the most accurate floor slip test method, recommended by the UK HSE and the UK Slip Resistance Group and used regularly in slip and fall injury cases.

  Test equipment is expensive and the test requires an experienced operator to produce reliable results. The test sees a weighted foot swing from a horizontal position to strike the floor surface over a standardised distance and continue the swing producing a Pendulum Test Value with a needle on the adjacent scale. The greater the slip resistance of the floor, the more the foot is slowed and the lower the height of the needle on the scale. Floors with a low slip resistance will see the foot reach almost horizontal on the overswing, indicating a low PTV and a high risk of slipping.

  The method benefits from an extensive history of correlation to real slips on varied floor types and considerable development of the test method to increase accuracy and reproducibility of results. Whilst newer test methods can boast quicker, easier (and so cheaper) assessment of floors, they cannot compete with the significant history and development of the BS 7976-2 Pendulum method. As such the BS 7976-2 Pendulum is the only method recommended for slip and fall legal proceedings.

  We are of the firm opinion that if floor slip testing will not stand up to the scrutiny of a court then there is no benefit in it, so all of our assessments follow broadly the same method as those compiled for the court in slip and fall personal injury cases.

• What do PTV, SRV, R value, Rz, CoDF, A B C classification, mean?

  PTV – Pendulum Test Value
  The number produced by Pendulum testing, primarily but not limited to BS 7976-2. Values above 35 are classified as a low risk of slip. Values from 25 to 35 inclusive are classified as a moderate risk of slip. Values below 25 are classified as a high risk of slip.

  SRV – Slip Resistance Value
  The same as PTV, it is simply an older reference to the same.

  R value – A classification from DIN 51130 ramp testing.
  The classification is based on the angle at which a slip occurs when gradually inclining a test sample and ranges from R9 to R13. The test uses safety footwear and oil contamination and classifications span accepted risk categories so its usefulness is limited. It remains a popular way for manufacturers to classify floors however, as the lowest slip resistance classification, R9, can be misconstrued as offering satisfactory slip resistance.

  Rz – A specific parameter of the surface roughness of a material.
  Rz describes the mean vertical displacement of the test stylus as it is dragged across a horizontal sample. The value is often erroneously used as a measure of slip resistance, a purpose for which it is extremely unreliable. The Rz value fails to take into account the shape or density of the micro-profile, which can have a significant impact on slip resistance.

  CoDF – Coefficient of Dynamic Friction
  The true base description of slip resistance, CoDF values can be misleading as their accuracy depends entirely on the method used to produce them. A mass can be dragged across a floor surface and the force required to move it measured in order to produce a CoDF, in terms of pedestrian slip testing however, the value produced would be of little relevance to the heel strike and lubricating film mechanics of a real slip and so a poor indicator of pedestrian slip resistance.

  A B C classifications – A classification from DIN 51097 ramp testing.
  The classification is based on the angle at which a slip occurs when gradually inclining a test sample and ranges from 12° (A) to >23° (C). The method uses bare feet and soapy contamination, making it a valuable method for the assessment of products destined for wet leisure environments.

• What values must my floor achieve to ‘pass’ the slip test?

  It is important to note that Pendulum testing should not be considered to provide a pass/fail value. The legal requirement is that the surface is safe, posing an acceptably low risk of slip in the conditions of end use.

  PTV’s of 36 or higher (generated using BS 7976-2) are required in order to classify the surface as a ‘low risk of slip’, but crucially it is the conditions under which these values are achieved which can determine whether a surface is fit for purpose, safe, slip resistant, compliant and ‘passes’ the test.

  A shopping centre for instance, will typically provide a safe level of grip in the dry and a poor level of grip in the wet. Provided the floor can be maintained in a clean and dry condition responsible parties have fulfilled their statutory requirement of a safe level of grip. Conversely, a manufacturing environment providing a PTV of >36 in water wet conditions may still pose an undue risk of slipping if greasy/oily contamination cannot be avoided in end use.

  Many factors can affect the risk of a slip, which is why we conduct a Slips Potential Model risk assessment alongside Pendulum testing, to determine whether results produced are satisfactory.

• How regularly should testing be conducted in a floor?

  At least annually.

  Floors failing to achieve the required 36+PTV in the conditions of end use should be reassessed immediately after improvements have been made. There is no value in building up a record of a noncompliant surface over time.

  Floors achieving 36+PTV in the conditions of end use should be retested regularly but the period between tests should be determined based on factors such as the PTV achieved, variations across the surface, flooring type, traffic and recontamination rates and previous recorded PTV’s.

  There is no hard guidance on periods between testing, ultimately a constant record of compliant surfaces is the aim. Surfaces subject to varying contamination and cleaning regimes are more likely to generate varying slip resistances and so warrant a more frequent assessment.

  It should be noted that the slip resistance of a surface will, in most cases, inevitably change over time, even if that surface has been subject to an anti-slip treatment. Wet slip resistance depends heavily on the roughness of both the macro and micro profile. Macro profile edges wear over time, reducing the effectiveness with which they cut through a lubricating film and into the shoe sole. Micro profiles are subject to wear, but also become clogged with dirt and/or cleaning residues over time, smoothing the surface and reducing the effective dispersal of a lubricating film. The best way to combat losses in slip resistance are with an effective cleaning regime.

• Can I Have My Pendulum Calibrated Outside The UK?

  Yes, we’d advise that you look for a lab with suitable certification for performing the calibration.

• What Does The Law Require Outside Of The UK In Terms Of Slip Resistance?

  This group is primarily concerned with the UK, and as such we are not aware of the detail of the law in other countries. We do have a number of international members, who may be able to help in their own regions.

• Where Can I Hire A Surface Roughness Meter?

  We are not aware of anyone offering a hire service for roughness meters.

• How Do You Measure Slip Resistance In Barefoot Situations?

  The UKSRG guidelines cover the use of the pendulum for barefoot areas. The guidelines detail a secondary rubber slider which is used to assess barefoot slip potential in wet conditions. The use of Rz microroughness measurements to supplement pendulum measurements is equally valid for barefoot situations. There are two standards for barefoot testing, but both are laboratory based, and so can not be used to assess installed flooring.

• How Do UKSRG Guidelines Relate To Vehicular Traffic In Car Parks?

  The UKSRG focuses on pedestrian safety, which does not extend to the slip resistance required by vehicles. For the pedestrians using the car park, the UKSRG Guidelines should be used to assess the slip potential, in the same way as they are used for any other pedestrian areas.

• What Level Of Slip Resistance Is Required In School Corridors And Class Rooms?

  The slip resistance required is dependent on the use of an area. The basic conditions in the guidelines are based on a biomechanical study of working age men walking at a normal pace. Where people are likely to run, they may need a higher level of slip resistance. You also need to consider the likelihood of the area becoming wet in normal use, for example a laboratory or workshop may need to be slip resistant when wet, whereas a typical class room would normally be dry.

• Do You Have Test Results Available For Specific Products?

  No, the UKSRG does not hold such information. Individual members may have experience of particular products. Some information on generic level of slip resistance for different materials are available in “Safer surfaces to walk on – reducing the risk of slipping” published by CIRIA.

• Can You Test The Slip Resistance Of Footwear?

  The Health & Safety Laboratory (HSL) and the Shoe and Allied Trades Research Association (SATRA) routinely undertake footwear slip testing, though they do not use the same methodology. HSL tend to use a ramp based methodology developed from the EN & DIN flooring standards, whereas SATRA use a mechanical test they have developed, and which is used in the EN safety footwear standard. The UKSRG has yet to form a view on which test method is the most appropriate

• Can Manhole Covers & Other Profiled Surfaces Be Pendulum Tested?

  Yes, in relation to pedestrian safety, we suggest referring to the profiled flooring section in the UKSRG guidelines.

• Can I Increase The Slip Resistance Of Shiny Flooring Without Changing Its Appearance?

  The slip resistance in wet conditions is related to the surface texture of the flooring. Acid etching treatments will increase slip resistance but make surfaces rougher and less shiny. Alternative, water-based slip resistance treatments are, however, available which have little or no effect on a floor’s appearance.

• Can I prevent my deck from becoming slippery?

  Yes. The surface of the deck needs to be kept clean and clear of mildew and algal growth. The Timber Decking and Cladding Association provides guidance on how and when to clean you deck on the Deck Maintenance page. Anti-slip decking products can also be fitted retrospectively, the TDCA can help you locate suitable suppliers. Decking products are available with anti-slip inclusions, which would avoid the problem.

• Where Can I Hire A Pendulum Tester?

  You can hire the pendulum from BSI Calibration in Hemel Hempstead. However, using the pendulum tester is not easy without training, so this may be a time consuming exercise that could easily result in mis-leading data. We would suggest contracting an expert user, such as a UKSRG member.

• Do I Need Training To Use The Pendulum?

  We would recommend that any new user undertake some training with an experienced operator.

• Who Can Test The Slip Resistance Of My Flooring?

  We suggest visiting the members page on this web site, where you can filter the membership by types of activity. If you have a question which is not answered below please email [email protected].

• Do Different Standards Apply To Different Flooring Materials?

  Yes, there are lots of standards for flooring materials. However, using the UKSRG guidelines will help you understand the slip potential of any flooring material. You may want to assess flooring in this way in addition to any flooring-specific standards. The guidelines will also assist you in considering the effects of cleaning, wear and use of the area into which the flooring will be installed.

• Does A Flooring Material Have An Absolute Value Of Slip Resistance?

  No, the level of slip resistance will also depend on the shoe material in contact with it, and any contamination that may be present between the two. For specification purposes, the shoe material and the test conditions are defined, allowing one material to be compared with another

• What Does The Law Require In The UK In Terms Of Slip Resistance?

  There are various regulations that apply to different premises, and different activities, but essentially they all require that the floor is not slippery in normal use. None of the regulations define the level of slip resistance required, or the test protocols that should be followed.