PTV Rating for Decking Explained: What Is a Good Slip Resistance Result?
A PTV rating for decking provides measured evidence of how much slip resistance a walking surface offers. This guide explains Pendulum Test Values, the commonly used 36+ benchmark, wet and dry testing, test directions and what to check before specifying anti-slip decking.
What Is a PTV Rating for Decking?
PTV stands for Pendulum Test Value. It is the numerical result produced by a pendulum slip-resistance test. In simple terms, the test measures how much friction a surface provides when a rubber slider passes across it. A higher number indicates greater measured slip resistance under the test conditions.
The pendulum method is particularly useful for decking because it can assess a surface in both dry and water-wet conditions. Portable equipment can also be used on an installed surface, allowing an existing walkway, bridge, terrace or boardwalk to be assessed rather than relying only on data from a new sample in a laboratory.
PTV gives specifiers, contractors, facilities managers and property owners objective evidence. Descriptions such as “textured”, “ribbed”, “grooved” or “anti-slip” may sound reassuring, but they do not quantify performance. Two boards that look similar can produce very different results when wet.
PTV is evidence, not a marketing description
A genuine result should be supported by a test report identifying the exact product or board configuration, the test method, wet or dry condition, slider, test direction and recorded values. A claim such as “non-slip finish” without suitable test evidence gives a specifier much less useful information.
What Do PTV Results Mean?
The familiar PTV classifications divide results into three broad slip-potential bands. These help turn a numerical reading into a practical indication of risk.
Low Risk of Slip
A result of 36 or above is generally classified as Low Risk of Slip. For outdoor decking, this classification should be achieved in conditions representative of expected use, which normally means considering the wet result.
Moderate Risk of Slip
Results from 25 to 35 are generally classified as Moderate Risk of Slip. The surface, users, likely contamination and available control measures should be considered carefully.
High Risk of Slip
Results from 0 to 24 are generally classified as High Risk of Slip. A low result is a clear reason to review the walking surface and the measures used to control slip risk.
It is tempting to call 36 a universal “pass mark”, but this oversimplifies slip safety. The duty is to manage risk in the conditions that can reasonably be expected. A surface that records 40 when clean and dry may not be suitable if it falls below that level when wet, contaminated or worn. Equally, a number from a laboratory report does not remove the need for correct installation, drainage, cleaning and inspection.
The useful question is therefore not only “Is the PTV above 36?” It is “Was an appropriate PTV achieved on the correct product, in the relevant condition and direction, using a suitable test procedure?”
How Does the Pendulum Slip Test Work?
The testing instrument has a weighted swinging arm with a standard rubber slider at its end. The slider represents the contact between footwear and a pedestrian surface. When released, it travels across a controlled section of the test surface. Friction slows the swing and the instrument records a Pendulum Test Value.
Before formal readings are taken, the equipment must be set up, checked and operated in accordance with the relevant method. The condition of the slider, contact length, surface preparation and temperature can all affect the accuracy of the result. This is why meaningful product testing should be undertaken by a competent independent tester rather than reproduced as an informal demonstration.
| Test stage | What happens | Why it matters |
|---|---|---|
| Equipment preparation | The pendulum, slider and test area are checked and prepared. | Controlled preparation supports repeatable, credible results. |
| Dry testing | The clean surface is tested without water contamination. | Shows baseline performance, but does not represent rain-wet external use by itself. |
| Wet testing | Water is applied and readings are repeated in the specified manner. | Provides the more relevant comparison for decking routinely exposed to rain. |
| Directional testing | The surface is assessed in defined directions. | Profiles, grain and anti-slip insert layouts can perform differently with direction. |
| Reporting | Readings, calculations, conditions and classifications are documented. | Allows the result to be interpreted and linked to the exact tested configuration. |
A product headline should never replace the full report. The report explains what was tested and how the published result was obtained.
Why Are Wet PTV Results So Important for Decking?
External decking in the UK is predictably exposed to rain, dew, frost and water carried on footwear. It may also be affected by algae, moss, mud, leaves and organic debris. A clean, dry reading can show that a board has adequate friction in ideal conditions, but it does not answer the most important question for many outdoor projects: how does the surface perform when wet?
Water can form a lubricating layer between a shoe and the deck. Biological growth can make this worse, particularly in shaded locations where boards dry slowly. Marinas, bridges, boardwalks, viewing platforms, ramps, hospitality terraces and public access routes may experience persistent wetting or concentrated foot traffic.
GripDeck’s 2026 comparison testing illustrates the difference clearly. A 145mm standard grooved decking board without anti-slip inserts recorded a dry median PTV of 69, which was within the Low Risk classification, but its wet median PTV fell to 30, within the Moderate Risk classification. The visual presence of grooves did not guarantee low slip risk when the board was wet.
Do not specify outdoor decking from a dry figure alone
Where water is foreseeable, ask for the wet PTV and confirm that the tested board matches the product being supplied. A strong dry result can conceal a significant fall in performance once water is introduced.
Why Does the Direction of Testing Matter?
Decking is not a uniform surface. Timber grain, grooves, raised profiles and anti-slip inserts all have a direction. The same board may therefore produce different readings depending on how the pendulum slider crosses it.
Across the board width
For GripDeck’s current reports, the 0° direction represents testing across the width of the boards. The slider crosses the timber and anti-slip insert layout, providing a useful representation of pedestrian contact across the board.
Along the board length
The 90° direction follows the board length. This can be relevant on bridges, ramps and long walkways where the main pedestrian route may run in the same direction as the boards.
When comparing test data, check whether a headline figure is a mean, median, lowest individual result or selected directional result. These are not interchangeable. GripDeck’s current results table states that its headline figures are 0° median PTV values, while the full independent reports contain the additional readings and methodology.
Direction also affects product specification. Two GripDeck® inserts are suitable for most applications. Three inserts may be recommended where the principal direction of travel follows the length of the board, including bridges, ramps, boardwalks, platforms and long public walkways. The extra central insert increases anti-slip coverage and reduces the space in which a foot could land between the two outer inserts.
Need the Independent Test Reports?
View and download GripDeck® wet and dry slip-resistance reports for current board configurations and RetroGrip® inserts.
BS EN 16165, BS 7976 and UKSRG Guidance
BS EN 16165:2021 is the current British Standard covering methods for determining the slip resistance of pedestrian surfaces. Annex C covers the pendulum method. Older reports may refer to BS 7976, which was the previous British Standard associated with pendulum testing.
An older BS 7976 report should not automatically be dismissed. The test date, slider, conditions, procedure and relevance to the supplied product need to be reviewed. GripDeck’s latest 2026 factory-applied decking reports use BS EN 16165:2021 Annex C and are assessed using UK Slip Resistance Group Guidelines Issue 6.
The standard describes how testing is performed; guidance is then used to interpret slip potential. This distinction matters. A report should not imply that one number alone guarantees legal compliance in every environment. Designers and responsible parties still need to consider the foreseeable users, contamination, gradient, direction of movement, cleaning arrangements and consequences of a fall.
Terminology you may see in reports
- PTV: Pendulum Test Value, the result produced by pendulum testing.
- SRV: Slip Resistance Value, an older term commonly used for a pendulum result.
- Slider 96: a rubber slider commonly used to represent footwear contact.
- Slider 55: a softer slider used for particular situations, including assessment relevant to barefoot use.
- Wet or water-wet: testing with water present on the surface.
- Ex-factory testing: testing a new manufactured product before service exposure.
- In-situ testing: testing a surface after it has been installed and is in use.
How to Read a Decking Slip Test Report
A credible report should let you connect the result to the product and intended application. Before relying on a headline PTV, work through the following checks.
Identify the product
Confirm the timber profile, board width, number of inserts and surface configuration. A result for one product should not be casually transferred to a materially different design.
Check wet and dry conditions
For external decking, look for the water-wet result as well as the dry result. Confirm which classification applies to each condition.
Check test directions
Understand how 0°, 90° and any additional direction relate to the board and the likely pedestrian route. Do not compare unlike directional figures.
Check the reported statistic
Identify whether a published figure is a mean, median, corrected value or lowest result. Read the full data rather than assuming all summaries use the same calculation.
Check the slider and method
The report should state the standard or procedure and the slider used. These details help establish whether the test reflects the intended pedestrian conditions.
Check the sample condition
New laboratory samples provide controlled product comparison. Installed surfaces may change through weathering, wear, cleaning residues and contamination, so ongoing assessment still matters.
What PTV Results Did GripDeck® Anti-Slip Decking Achieve?
GripDeck® anti-slip decking was independently tested in 2026 using representative smooth and grooved board configurations. The test programme covered 115mm and 145mm boards with two or three factory-applied resin-and-aggregate inserts. A standard 145mm grooved decking board without inserts was also included as a comparison.
| Product tested | 0° dry median PTV | 0° wet median PTV | Classification |
|---|---|---|---|
| 145mm Smooth GripDeck® – 2 inserts | 82 | 72 | Low Risk |
| 145mm Smooth GripDeck® – 3 inserts | 84 | 73 | Low Risk |
| 145mm Grooved GripDeck® – 2 inserts | 79 | 69 | Low Risk |
| 145mm Grooved GripDeck® – 3 inserts | 91 | 73 | Low Risk |
| 115mm Smooth GripDeck® – 2 inserts | 82 | 71 | Low Risk |
| 145mm Standard Grooved Decking – no inserts | 69 | 30 | Moderate Risk when wet |
These are the published 0° median results. Always refer to the current complete reports on the GripDeck® Anti-Slip Test Results page for methodology, additional readings and classifications.
All tested GripDeck® factory-applied configurations achieved a Low Risk of Slip classification in both dry and wet conditions. Both smooth and grooved GripDeck® boards performed strongly, showing that the anti-slip system is created by the resin-and-aggregate insert configuration rather than by assuming grooves alone will provide grip.
RetroGrip® inserts for suitable existing grooved timber decking have also been independently tested. Hardwood decking fitted with RetroGrip® recorded a mean dry PTV of 96 and a mean wet PTV of 72, both classified as Low Risk of Slip.
Softwood Anti-Slip Decking
Cost-effective European Redwood decking with factory-applied aggregate inserts.
View SoftwoodHardwood Anti-Slip Decking
Premium anti-slip timber for marinas, bridges, hotels and public access projects.
View HardwoodRetroGrip® Inserts
Retrofit improved grip to many existing grooved timber decking boards.
View RetroGrip®How Should PTV Be Used When Specifying Decking?
PTV should form part of a complete decking specification, not sit as an isolated number. Start with the people who will use the area and the conditions likely to occur. A private garden terrace, care-home ramp, school walkway, marina, viewing platform and footbridge do not carry identical risks.
A practical specification checklist
- Describe the intended location, pedestrian use and foreseeable contamination.
- Request wet and dry independent PTV results for the proposed board configuration.
- State the board width, profile, timber option and number of anti-slip inserts.
- Consider whether pedestrians travel across the boards or mainly along their length.
- Use three inserts where the project assessment and direction of travel justify the extra coverage.
- Specify correct drainage gaps, ventilation, support spacing and corrosion-resistant fixings.
- Include cleaning, inspection and periodic reassessment within the management plan.
- Retain product data, test reports and maintenance records for the completed project.
For new decking, factory-applied inserts provide controlled positioning and a permanent high-grip surface integrated into the board. For existing grooved timber decking that remains structurally sound, RetroGrip® may provide a practical alternative to full replacement. Anti-slip products cannot repair rotten boards, failed fixings or an inadequate substructure, so the existing deck should always be inspected first.
Maintenance remains essential. No external decking should be treated as maintenance-free. Leaves, mud, algae and moss should be removed, drainage gaps kept clear and defects addressed. Product test data describes performance under the stated test conditions; it cannot guarantee that an installed deck will remain safe if it is allowed to become heavily contaminated or structurally unsound.
Frequently Asked Questions About PTV Ratings for Decking
What does PTV stand for?
PTV stands for Pendulum Test Value. It is the numerical result produced by a pendulum slip-resistance test. Higher values indicate greater measured slip resistance under the stated test conditions.
What is a good PTV rating for decking?
A PTV of 36 or above is generally classified as a Low Risk of Slip. For outdoor decking, check that this is achieved in wet conditions and that the test applies to the proposed board configuration.
Is PTV 36 a legal pass mark?
It should not be treated as a universal legal pass or fail. A value of 36+ is a widely used Low Risk classification, but the responsible party must assess safety in the expected conditions of use, including contamination, users, installation and maintenance.
Should outdoor decking be tested wet?
Yes, wet performance is especially relevant because rain and moisture are foreseeable on external decking. A dry result alone may give a misleading impression of wet-weather safety.
Is grooved decking automatically anti-slip?
No. Grooves do not prove wet slip resistance. GripDeck’s standard grooved comparison board recorded a wet median PTV of 30, classified as Moderate Risk, while grooved boards with factory-applied GripDeck® inserts achieved Low Risk classifications.
What is the difference between PTV and SRV?
SRV means Slip Resistance Value and is an older term frequently used for the result of pendulum testing. When reviewing an older report, check its complete method and conditions rather than relying on the terminology alone.
What is the difference between BS EN 16165 and BS 7976?
BS EN 16165:2021 is the current standard covering methods for evaluating slip resistance of pedestrian surfaces. BS 7976 was the earlier British Standard used for pendulum testing. Older reports may still provide useful evidence when the method, slider, conditions and product remain relevant.
Why are decking boards tested in different directions?
Board grooves, timber grain and insert layouts have a direction, so performance may vary across and along a board. The report should identify how each test direction relates to the product.
Does a high laboratory PTV mean decking needs no maintenance?
No. External decking can accumulate algae, moss, mud, leaves and cleaning residue. Regular cleaning, inspection, drainage and appropriate maintenance are still required.
Can existing decking be PTV tested?
Yes. One advantage of portable pendulum equipment is that a competent tester can assess many installed pedestrian surfaces. In-situ results reflect the condition of the tested area at that time.
Are two anti-slip inserts enough?
Two GripDeck® inserts are suitable for most applications. Three may be recommended where the main direction of travel runs along the board length, such as bridges, ramps, boardwalks and long walkways.
Where can I download GripDeck® test reports?
The latest available reports and result summaries can be downloaded from the GripDeck® Anti-Slip Test Results page.
PTV Helps You Compare Decking Using Evidence
A PTV rating turns slip resistance from a visual claim into measurable evidence. For decking, the most useful information is normally the wet result for the correct board configuration, supported by a full independent report that identifies the method, slider, direction and conditions.
A result of 36 or above is generally classified as Low Risk of Slip, but safe specification goes further. Board design, insert spacing, direction of travel, drainage, users, contamination and long-term maintenance all need to be considered. Used correctly, PTV data helps buyers and specifiers compare products more confidently and select a complete decking system suited to the real project.
Need Help With a Decking Specification?
GripDeck® can provide test reports, samples and advice on timber, board profile and two- or three-insert layouts.