Slip Resistance Ratings for Glass Floors: Choosing a Surface

A clear glass floor can offer far less grip when wet than its appearance suggests. For a slip resistance rating for glass floors, the wet Pendulum Test Value (PTV) is a useful measure: a result above 36 is classed as slip-resistant in most projects. The surface finish matters, and the test needs to reflect the conditions in which the floor will be used.

Choosing a finish means balancing traction with transparency, light transmission, appearance and cleaning needs. Ceramic frit can create a durable textured surface, while sandblasting and acid etching offer different combinations of grip and visual effect. This guide explains the main surface options, how ceramic frit influences slip resistance, and how wet testing and ratings can inform a glass-floor design.

Where is anti-slip glass used?

Anti-slip glass is used where a pedestrian surface must balance visibility with traction, including hotels, apartment buildings and cultural institutions. Indoor and outdoor applications differ chiefly in exposure: an indoor floor may stay dry, while an entrance, rooflight or bridge can become wet. Public areas also experience regular foot traffic, so the finish and test conditions should reflect how people use the surface.

There isn’t one slip resistance rating for every indoor, outdoor and public glass floor. The relevant PTV depends on the finish and whether testing is done in dry or wet conditions. Outdoor surfaces are often assessed when wet, as moisture can increase slip risk.

A Pendulum Test Value (PTV) describes the result of a pendulum test on a surface. The pendulum’s rubber slider passes over the test area, and the reading indicates the surface’s slip resistance under the test conditions. For a pedestrian floor tested in service in a UK shod area, the HSE approach uses slider 96. BS EN 16165:2021 provides for slider 96 and slider 57, with dry measurements, wet measurements or both.

PTV ranges offer a way to interpret results. A PTV from 0 to 24 is classed as extremely low slip resistance; 25 to 35 is low; 36+ is moderate; and 75+ is high. A PTV above 36 is classed as slip-resistant in most projects. These bands help describe the result, but the appropriate target depends on the floor’s use and exposure.

The UK HSE approach measures pedestrian surfaces with a pendulum in line with its guidance. The UK Slip Resistance Group also recommends pendulum measurement. Neither sets a single HSE PTV threshold for every floor.

BS EN 16165:2021 covers ramp, pendulum and tribometer methods for evaluating pedestrian-surface slip resistance. BS EN 13845:2017 gives ramp-test criteria for shod and barefoot areas, while BS 7976 details the pendulum method. These standards provide testing frameworks, rather than one universal rating for every glass floor.

Ramp and pendulum results don’t correlate directly, so an R rating from ramp testing can’t be converted into a PTV. For example, BS EN 13845:2017 requires a ramp-test angle of at least 20° for shod areas and 15° for barefoot areas. A PTV comes from a different test method and should be read as its own result.

For walk-on glass, specifying the surface alongside the test method makes the result meaningful. Walk-on glass floors can be designed with finishes suited to the intended application, with toughened glass forming part of the structural build-up.

Non-slip glass floors: what are my options?

Choose a finish by balancing grip with transparency, appearance and cleaning requirements. Sandblasting, acid etching and ceramic frit create different surface properties for indoor and outdoor applications.

Patterned and Sandblasted Finishes

Patterned finishes add textured areas to glass, while sandblasting roughens selected sections or the whole surface. A CNC-made pattern can leave untreated glass areas clear, balancing grip with views through the floor. Sandblasting depth can also vary translucency and traction. A fully sandblasted finish has an approximate wet PTV of 50, while sandblasted surfaces can range from PTV 50 to 57.

This balance matters where a basement floor needs both light transmission and privacy. Sandblasted glass may wear faster under foot traffic than acid-etched or ceramic-fritted glass. Its gritty texture can also trap dirt, and the surface often needs sealing. These factors matter when choosing a finish for a busy route or outdoor area.

Anti-Slip Finishes and Treatments

Anti-slip treatments increase friction by changing the glass surface through ceramic frit, acid etching or sandblasting. Acid-etched glass can offer a more durable, easier-to-clean alternative to sandblasted glass, with wet PTV results of 40-45. Ceramic frit creates a distinct textured surface, while sandblasting can be applied selectively or across the whole panel.

Each treatment affects the balance between grip, clarity and maintenance. Consider the finish alongside expected foot traffic and whether water may reach the floor. For a rooflight, the finish must also suit how the glass will be used. A walk-on glass rooflight brings that design question into an exposed setting.

To maintain slip resistance, keep the surface clean using a method suited to its finish, and inspect it for visible wear or damage. Retesting can be useful after a change in condition, such as wear to a sandblasted area or the application of a new treatment, because test results describe the surface as tested.

Coatings and surface treatments can change grip, clarity and cleaning behaviour. A treatment that wears unevenly may leave areas with different surface properties. Assess the finished glass under wet conditions rather than assuming its original performance remains unchanged.

For example, a patterned sandblasted floor can retain clear viewing zones, but its textured sections need assessment as foot traffic wears them. A fully sandblasted panel offers a more consistent texture, while acid etching may suit a project where cleaning and durability matter more. Let the intended use, exposure and maintenance approach guide the selection.

Ceramic frit patterns and slip resistance

Ceramic frit adds texture to glass through fired ceramic particles. The frit is screen-printed in a pattern, then fired at high temperatures so it bonds structurally with the glass. This creates a permanent textured surface rather than a separate layer applied after installation. The pattern can therefore contribute to both the floor’s appearance and its grip.

Coverage shapes the visual effect. A fully fritted surface gives a more continuous texture, while a patterned treatment leaves areas of clear glass between printed sections. These choices affect how open or obscured the view below appears. They also determine where textured areas sit underfoot, so consider the pattern alongside the floor’s use and layout.

Reported wet slip results offer a useful point of comparison. A fully ceramic-fritted glass surface has an approximate PTV of 60. Ceramic frit particle fusion is reported at R12-R13 and PTV 55-60. These figures describe results associated with particular finishes and tests, not a universal value for every frit pattern. The selected surface and test conditions matter.

Frit’s bond with the glass is central to its performance. Because the ceramic treatment is fired into the surface, it is structurally bound rather than simply laid over the glass. This distinguishes it from a coating that sits above the substrate. On a floor, its integrated texture can combine a defined pattern with an enduring surface finish.

Consider the test result alongside the visual specification. A PTV measures slip resistance using the pendulum method, while an R classification comes from ramp testing. Because the ratings use different methods, read each result in context rather than treating the labels as interchangeable. Standards and test conditions are part of the performance information.

Acid-etched glass is another finish associated with anti-slip performance, with a different surface character from ceramic frit. Choosing between etched and fritted glass affects the balance of texture, visibility and pattern. A frit pattern can preserve clear viewing areas, while broader coverage creates a more consistently textured appearance. Assess the tested finish in its intended use.

For a walk-on glass floor, the frit pattern is one part of a wider specification. Consider where pedestrians will cross the panel, whether the area may become wet, and how much transparency the design requires. Then interpret the wet PTV for the chosen finish in light of the relevant test method. This links the visual pattern to measured slip performance.

Slip resistance testing for structural glass floors

Slip resistance and structural capacity answer different questions. Pendulum, ramp and tribometer tests assess surface grip; structural design considers loads, spans, support and glass build-up. BS EN 16165:2021 includes all three pedestrian-surface testing methods. Its results aren’t interchangeable, so specify which method produced each reported value.

Testing should reflect the conditions where people walk. BS EN 13893:2002 assesses dynamic friction on dry floors only, with a minimum coefficient of friction of 0.3 for CE marking. That dry measurement doesn’t establish grip in wet conditions. For a fuller picture, flooring testing should include wet and dry conditions, particularly where rain or water may reach the surface.

For UK in-service assessment of a shod pedestrian area, the HSE uses a pendulum with slider 96. The UK Slip Resistance Group also recommends pendulum measurement, following HSE guidance. BS 7976 details the Pendulum Test Method. Record whether the surface was tested wet or dry, and the slider used, because these details define the conditions behind the PTV.

Grip testing doesn’t assess how a glass panel behaves under load. Typical internal glass-floor design uses a load of 1.5 kN/m², with a glass build-up of 25.5-31.5 mm for standard spans. These are typical figures, not a specification for every architectural project. Span, support and intended use affect structural glazing design, independently of the surface finish.

Walk-on floors commonly use toughened laminated glass, made from two panes bonded by an interlayer such as PVB, EVA or Sentry. Lamination helps retain fragments and keep a cracked panel in place. BS EN 14449 sets requirements for laminated glass. The glass make-up and its interlayer therefore relate to safety and structural performance, not to the slip result alone.

Interpret surface testing alongside the panel’s construction. A wet PTV describes the tested finish, while the laminated build-up addresses how the assembly contains damage. Neither result replaces the other. A textured surface may provide grip, for example, but it does not establish the panel’s capacity for its design loads.

For a complete specification, align the surface test conditions with the floor’s intended use, then assess the glass build-up against its structural requirements. An international standard can define a test method, but the reported result still applies to the surface and conditions tested. Keeping these distinctions clear helps architects and project teams assess slip performance without confusing it with structural strength.

Wet slip-resistance ratings for glass floors

Wet testing matters because a dry result can’t show how a surface performs when water is present. Pendulum Test Values (PTVs) describe slip resistance under stated test conditions. A PTV above 36 is classed as slip-resistant in most projects, while the conditions and finish tested remain essential context.

The broad PTV bands help interpret results: 0-24 indicates extremely low slip resistance, 25-35 low, 36+ moderate and 75+ high. These categories describe measured performance; they aren’t a universal specification for every floor. A project’s intended use and exposure inform the target, particularly where external glazing may become wet.

Finish influences the wet result. Acid-etched glass can achieve a wet PTV of 40-45, while specialist anti-slip glass varies from 18 to 57 depending on type. Sandblasted glass is reported at PTV 50-57, and ceramic-fritted surfaces at 55-60. These ranges illustrate why a finish name alone can’t replace a test result.

For external glass floors, PTV 50-60 is preferred in the supplied market guidance. That higher target reflects the need to consider wet exposure, rather than relying on a dry-floor result. A fully sandblasted surface, for example, has an approximate wet PTV of 50. The actual test result should be tied to the specific finish and conditions.

R ratings use ramp testing, not the pendulum method. DIN 51130 places R10 above 10° up to 19°, R11 above 19° up to 27°, and R12 above 27° up to 35°. These classes cannot be directly converted into PTVs, so technical specifications should identify the test method instead of presenting the labels as equivalents.

Testing wet and dry helps distinguish how a surface behaves across conditions. For a shod pedestrian area assessed in service in the UK, the HSE uses a pendulum with slider 96. Recording the slider and whether the test was wet or dry makes a result more useful when comparing finishes or assessing a replacement panel.

Slip performance is only one part of a structural glass specification. Toughened laminated glass, its supporting structure and its tested surface address different design considerations. A wet PTV doesn’t establish the panel’s structural capacity, and a glazing build-up doesn’t establish its grip. Keep these assessments separate when reviewing a glass-floor design.

For a project-specific surface and structural specification, discuss your glass-floor requirements in the context of the intended use and exposure.

HSE guidance and BS 7976 are identified as references for the wet slip-resistance recommendation for floors. Acid-etched glass is stated to achieve R10-R11 and PTV 40-50, illustrating that ramp and pendulum results provide different descriptions of a surface.

For outdoor bridges, the recommendation is to combine the outdoor bridge rating with PTV 50+ in wet conditions. R10 is described as suitable for light-moisture zones at 10°-19°, R11 for frequent wet exposure at 19°-27°, and R12 for high-risk wet areas and outdoor bridges at 27°-35°.

Structural Glass Design

Structural Glass Design Ltd can help translate slip-resistance findings into a complete glass-floor specification. The company designs, manufactures and installs load-bearing structural glass systems, considering the surface finish alongside structural requirements and the intended setting.

For a project, the key decisions include the tested finish, wet or dry exposure, panel use and structural build-up. Structural Glass Design Ltd offers bespoke solutions for walk-on glass floors, as well as rooflights, drive-on floors and glass boxes. This is relevant when architectural design calls for a walkable glass surface and grip must be considered with the wider system.

Contact Structural Glass Design Ltd to discuss your glass-floor project.

Shape your glass-floor specification

Use the surface decision to shape the project brief, rather than treating it as an isolated finish choice. A suitable slip resistance rating for glass floors should be considered alongside the space’s intended use, desired transparency and maintenance needs. Bringing these priorities together early helps align the architectural design and technical specification.

Structural Glass Design Ltd can help develop glass solutions around the requirements of your project, including Walk on Glass Floors, Walk on Glass Rooflights and Drive on Glass Floors & Rooflights. Set out the location, expected use and visual intent, and the surface-performance discussion can sit within the wider structural design process.

Discuss your glass floor with Structural Glass Design Ltd and take the next step towards a considered, well-integrated design.

Frequently Asked Questions

What pendulum test value (PTV) is recommended for glass flooring?

A PTV above 36 is classed as slip-resistant in most projects, while external glass floors are often designed around a preferred wet PTV of 50-60. The appropriate target depends on exposure and use. For example, a covered internal floor and an exposed outdoor walkway face different wetting conditions. Specify the test condition alongside the value, so the result reflects the surface’s intended setting.

How do R ratings compare with PTV ratings for glass floors?

R ratings and PTVs come from different tests, so one cannot be reliably converted into the other. R classifications describe ramp-test results, while a PTV comes from a pendulum test. A specification should identify the method behind each result. If a design uses both ratings, assess them as separate performance information rather than assuming matching numbers represent equivalent grip.

Which test methods are suitable for assessing slip resistance on glass flooring?

BS EN 16165:2021 includes ramp, pendulum and tribometer methods for pedestrian surfaces. The pendulum method can assess wet or dry conditions, making it relevant where water may reach glazing. BS EN 13893:2002 measures dynamic friction on dry floor surfaces only. Select a method suited to the question being assessed, and record the test condition so the result has practical context.

How does wet glass flooring affect slip resistance and recommended ratings?

Water can reduce grip on glass: untreated glass has a wet PTV below 20 and is described as slippery. A dry test alone cannot show performance when a floor is wet. For a glass floor exposed to rain or cleaning water, assess the finished surface under wet conditions. External applications commonly favour PTV 50-60, while the specific use and exposure inform the design target.

What finishes or treatments improve the slip resistance of glass floors?

Ceramic frit, acid etching and sandblasting can provide textured surfaces that improve grip. Their results and visual properties differ: for example, acid-etched glass can achieve wet PTV 40-45, while ceramic-fritted surfaces are reported at PTV 55-60. A slip resistance rating for glass floors should relate to the actual finish selected, not just its treatment name. Consider pattern, transparency and cleaning needs together.