Independent Anti-Slip Decking Test Results
Current GripDeck® anti-slip decking test data for smooth and grooved timber decking boards, tested to BS EN 16165:2021 Annex C and assessed using UKSRG Guidelines Issue 6.
Independently Tested GripDeck® Anti-Slip Decking
GripDeck® anti-slip decking has been independently pendulum tested by Slip Guru Ltd for the purpose of product certification. The latest testing covers representative GripDeck® board configurations based on board width, board profile and number of anti-slip inserts.
The current test reports cover 115mm and 145mm wide GripDeck® boards in smooth and grooved profiles, with 2 or 3 factory-applied anti-slip inserts. A 145mm wide grooved standard decking board without GripDeck® inserts was also tested for comparison.
All GripDeck® anti-slip decking configurations tested achieved a Low Risk of Slip classification in both dry and wet conditions. The standard grooved decking board without inserts achieved a Low Risk of Slip classification in dry conditions but a Moderate Risk of Slip classification in wet conditions.
Why We Test by Insert Configuration
GripDeck® anti-slip decking is manufactured in many timber options, including European Redwood softwood, hardwood species such as Balau, Iroko, Cumaru and Oak, and thermally modified ThermoDeck®. Testing every timber species separately would not provide the clearest comparison because the anti-slip performance is created by the resin and aggregate insert system.
The 2026 test programme therefore focuses on the key factors that affect slip resistance:
Number of Inserts
GripDeck® decking is commonly manufactured with 2 or 3 factory-applied anti-slip inserts depending on board width, application and direction of travel.
Board Profile
Smooth and grooved timber decking boards were tested so specifiers can compare common GripDeck® board profiles.
Board Width
115mm and 145mm board widths were included to represent common GripDeck® anti-slip decking sizes.
Why Insert Spacing Matters
One important factor in GripDeck® anti-slip decking performance is the spacing between the factory-applied anti-slip inserts. On a typical 145mm wide board with 2 inserts, GripDeck® inserts are positioned with approximately 70mm between insert centres.
This spacing is generally smaller than the width of an adult foot or shoe. In normal pedestrian use, this means the sole is very likely to be in contact with at least one anti-slip insert while walking across the decking. The insert layout is therefore designed around real foot contact rather than relying only on the timber surface between inserts.
70mm Insert Centres
GripDeck® 2-insert boards are designed with close insert spacing to maximise contact with footwear during normal walking.
Smaller Than a Typical Foot
The spacing between insert centres is generally less than the width of a person’s shoe, helping ensure regular contact with the anti-slip insert surface.
Engineered Walking Surface
The insert layout is part of the GripDeck® system and helps explain why the product performs strongly in wet and dry conditions.
Understanding What the Test Results Show
Pendulum testing measures the slip resistance of the complete decking board surface. During testing, the pendulum slider passes across both the timber surface and the GripDeck® anti-slip inserts. The published Pendulum Test Values therefore represent the performance of the full board configuration rather than the anti-slip insert material alone.
The GripDeck® inserts themselves provide a higher-grip surface than the surrounding timber. However, the published test result is intentionally representative of real-world pedestrian use because it reflects how the complete board performs as a walking surface.
What Is a Pendulum Slip Test?
A pendulum slip test measures how much grip a walking surface provides under controlled conditions. The result is shown as a Pendulum Test Value, or PTV. The higher the PTV, the greater the measured slip resistance.
The GripDeck® reports were tested to BS EN 16165:2021 Annex C (previously BS 7976 parts 1–3) and assessed against UKSRG Guidelines Issue 6. The reports also note that results were adjusted for temperature in accordance with the test standard.
| PTV Result | Slip Risk Classification | What It Means |
|---|---|---|
| 36+ | Low Risk of Slip | Target classification for most pedestrian surfaces in expected end-use conditions. |
| 25–35 | Moderate Risk of Slip | May require improvement depending on use, contamination risk and environment. |
| 0–24 | High Risk of Slip | Higher likelihood of slipping, especially when wet or contaminated. |
2026 Independent Test Reports
Download the independent Slip Guru test reports below. The table summarises the 0° Median Pendulum Test Value (PTV) for each product, representing the slip resistance measured across the width of the decking boards. All GripDeck® anti-slip decking configurations achieved a Low Risk of Slip classification in both dry and wet conditions.
| Product Tested | 0° Dry Median PTV | 0° Wet Median PTV | Classification | Report |
|---|---|---|---|---|
| 145mm Smooth GripDeck® – 2 Inserts | 82 | 72 | Low Risk | Download PDF |
| 145mm Smooth GripDeck® – 3 Inserts | 84 | 73 | Low Risk | Download PDF |
| 145mm Grooved GripDeck® – 2 Inserts | 79 | 69 | Low Risk | Download PDF |
| 145mm Grooved GripDeck® – 3 Inserts | 91 | 73 | Low Risk | Download PDF |
| 115mm Smooth GripDeck® – 2 Inserts | 82 | 71 | Low Risk | Download PDF |
| 145mm Standard Grooved Decking | 69 | 30 | Moderate Risk (Wet) | Download PDF |
Wet Decking Slip Resistance Comparison
The clearest comparison is in wet conditions. The 145mm grooved standard decking sample without inserts recorded a lowest wet PTV of 28 and was classified as Moderate Risk of Slip. The GripDeck® anti-slip decking samples recorded lowest wet PTV values from 36 to 47 and were classified as Low Risk of Slip.
Standard Grooved Decking
Wet lowest PTV: 30
Moderate Risk of Slip in wet conditions.
145mm Grooved GripDeck®
Wet lowest PTV: 69-73
Low Risk of Slip with 2 or 3 inserts.
145mm Smooth GripDeck®
Wet lowest PTV: 72-73
Low Risk of Slip with 2 or 3 inserts.
Smooth vs Grooved GripDeck®
The results show that both smooth and grooved GripDeck® boards with factory-applied inserts achieved Low Risk of Slip classifications in wet and dry conditions. This means the choice between smooth and grooved profiles can often be made based on appearance, project requirements, board profile and customer preference rather than slip resistance alone.
| Question | Answer |
|---|---|
| Is smooth GripDeck® anti-slip? | Yes. Smooth GripDeck® boards with factory-applied inserts achieved Low Risk of Slip classifications in wet and dry conditions. |
| Is grooved GripDeck® anti-slip? | Yes. Grooved GripDeck® boards with factory-applied inserts achieved Low Risk of Slip classifications in wet and dry conditions. |
| Does timber species change the result? | The insert configuration is the main factor in slip resistance. Timber species has relatively little effect compared with the factory-applied anti-slip inserts. |
2 Inserts or 3 Inserts?
Two GripDeck® inserts are suitable for most anti-slip decking applications and remain the most common layout. Three inserts may be recommended where the main direction of travel runs along the board length, such as bridges, ramps, boardwalks, long walkways and public access routes.
2 Insert Layout
Suitable for most applications and available on common GripDeck® board widths and profiles.
View Softwood Decking3 Insert Layout
Often specified where the primary direction of travel follows the board length or where additional coverage is required.
Discuss Your ProjectBespoke Advice
GripDeck® can advise on insert layout, board width, profile and timber species based on the project and expected use.
Ask for AdviceRetroGrip® Slip Test Results
RetroGrip® retrofit anti-slip inserts have also been independently pendulum tested. RetroGrip® is designed for suitable existing grooved timber decking where the boards are still sound but require improved slip resistance.
The independent Grip Potential test report for Hardwood decking with GripDeck RetroGrip strips recorded a Mean Dry PTV of 96 and a Mean Wet PTV of 72, with both dry and water-wet conditions classified as Low Risk of Slip.
The report also notes that the tested RetroGrip® surface featured an aggressive anti-slip resin strip and substantial macro-profile, with excellent wet and dry anti-slip properties. The conclusion states that the product presents a low risk of slip in both dry and water-wet conditions, and that testing was conducted to provide a worst-case minimum slip resistance.
| Product Tested | Dry PTV | Dry Classification | Wet PTV | Wet Classification | Report |
|---|---|---|---|---|---|
| Hardwood decking with GripDeck RetroGrip strips | 96 | Low | 72 | Low | Download PDF |
Retrofit Existing Decking
RetroGrip® is suitable for many existing grooved timber decking boards where improved slip resistance is required.
View RetroGrip®Mean Wet PTV 72
The independent RetroGrip® report recorded a mean wet PTV of 72, classified as Low Risk of Slip.
Download ReportExisting Decking Advice
Send photos of your existing grooved decking and GripDeck® can advise whether RetroGrip® may be suitable.
Ask for AdviceWhich GripDeck® Products Use This Test Data?
The 2026 testing supports GripDeck® anti-slip decking boards manufactured with equivalent insert configurations, board widths and profiles. This includes softwood, hardwood and thermally modified GripDeck® decking where the same insert technology and layout is used.
Softwood Anti-Slip Decking
Cost-effective European Redwood anti-slip decking for gardens, schools, commercial projects and public access routes.
View Softwood
Hardwood Anti-Slip Decking
Premium hardwood anti-slip decking for hotels, marinas, heritage sites, bridges and public access projects.
View Hardwood
ThermoDeck®
Thermally modified timber decking with anti-slip inserts for modern gardens, terraces and design-led projects.
View ThermoDeck®Laboratory Testing vs Real-World Decking Conditions
The published 2026 slip test results are based on new decking samples tested under controlled conditions. This is the correct approach for product certification and comparison, but external decking in real use will be exposed to weathering, moisture and contamination over time.
In real-world situations, all outdoor decking can be affected by rain, frost, algae, moss, leaf debris, dirt and general wear. These factors can reduce the slip resistance of conventional timber decking, particularly where boards are shaded, damp or not regularly cleaned.
GripDeck® anti-slip decking is designed so that the factory-applied resin and aggregate inserts continue to provide a reliable high-grip walking surface as the surrounding timber naturally weathers and ages. The timber surface will still require normal cleaning and maintenance, but the GripDeck® inserts are there to provide long-term slip resistance where standard timber alone can become slippery.
New Board Test Data
The 2026 reports provide controlled test data for new GripDeck® board configurations.
Real Weather Exposure
External decking may later be affected by rain, algae, moss, dirt, shade, frost and organic contamination.
Long-Term Grip from Inserts
The anti-slip inserts are designed to keep providing grip as the timber naturally weathers and ages.
Important Notes About Slip Resistance
Wet Conditions Matter
Outdoor decking should be assessed in the conditions expected in use. Wet PTV results are particularly important for external timber decking.
Contamination Risk
Responsible parties should consider likely contamination, including algae, moss, leaf debris, mud, rainwater and other site-specific conditions.
Cleaning Still Matters
Anti-slip decking should still be maintained and cleaned as part of a sensible safety and maintenance programme.
Frequently Asked Questions
Why has GripDeck® tested by board profile rather than timber species?
The anti-slip performance is created primarily by the factory-applied resin and aggregate insert system. Timber species has relatively little effect on the slip resistance result compared with insert quantity, board profile and insert layout.
Which GripDeck® boards achieved a Low Risk of Slip classification?
All GripDeck® anti-slip decking configurations tested in 2026 achieved a Low Risk of Slip classification in both dry and wet conditions.
How did standard grooved decking perform when wet?
The 145mm wide standard grooved decking board without GripDeck® inserts recorded a lowest wet PTV of 28 and was classified as Moderate Risk of Slip in wet conditions.
Is smooth GripDeck® anti-slip?
Yes. The smooth GripDeck® boards tested with factory-applied inserts achieved Low Risk of Slip classifications in both dry and wet conditions.
Is grooved GripDeck® anti-slip?
Yes. The grooved GripDeck® boards tested with factory-applied inserts achieved Low Risk of Slip classifications in both dry and wet conditions.
Do I need 2 inserts or 3 inserts?
Two inserts are suitable for most applications. Three inserts may be recommended where the main direction of travel follows the length of the board, such as bridges, ramps, boardwalks and long walkways.
Can I use these results for hardwood, softwood and ThermoDeck®?
Yes, where the product uses the same GripDeck® insert technology and equivalent board configuration. The test programme is based on insert layout, board profile and board width rather than timber species.
Why is insert spacing important?
Insert spacing affects how often a person’s foot contacts the anti-slip insert during normal walking. GripDeck® 145mm boards with 2 inserts have approximately 70mm between insert centres, which is generally smaller than the width of a person’s shoe.
Do the test results show the slip resistance of the insert alone?
No. Pendulum testing measures the complete board surface, including both the timber and the anti-slip inserts. The anti-slip insert itself has a higher-grip surface, but the published PTV reflects the tested performance of the full board configuration.
Are the test results based on new or weathered boards?
The 2026 reports are based on new boards tested under controlled conditions. In real-world use, decking can be affected by weathering, algae, moss, dirt and organic contamination. GripDeck® inserts are designed to continue providing grip as the surrounding timber naturally weathers and ages.
Has RetroGrip® been slip tested?
Yes. RetroGrip® retrofit inserts have been independently tested and achieved a Mean Dry PTV of 96 and Mean Wet PTV of 72, both classified as Low Risk of Slip.
Need Slip Test Data for Your Specification?
GripDeck® can provide test reports, samples and product advice to help you specify the right anti-slip decking board, insert spacing, board profile and insert layout for your project.