Plain glass would be, which is exactly why walk on panels are not supplied plain. The top surface carries an anti slip treatment, generally a ceramic frit fired into the glass or an etched pattern, specified to give grip when the surface is wet. What then matters is keeping it clean, because algae and film undo a good surface.
Why plain glass is a problem
Because it is smooth and it holds a film.
A polished surface with a layer of water on it gives very little for a shoe to grip, and on an external terrace it would be genuinely dangerous.
A ceramic frit
The commonest treatment. A ceramic ink is printed onto the glass and fired in during toughening, so it becomes part of the surface rather than a coating applied to it.
It does not wear off.
What a frit looks like
A pattern of dots, lines or squares.
The pattern is visible and it is part of the appearance of the panel, so it is chosen rather than accepted, and different manufacturers offer different designs.
Acid etching
The alternative surface. An etched finish gives a fine texture across the whole face, which reads as a frosted panel and provides grip without a printed pattern.
Applied anti slip finishes
Available and less durable. Surface applied treatments exist and they wear, which is why a fired or etched finish is what a purpose made panel uses.
How slip resistance is measured
By pendulum test, wet and dry. A standard test gives a value for the surface, and manufacturers publish figures for their finishes so a specification can be compared rather than assumed.
What figure to look for
The wet value, not the dry one.
Almost any surface performs well dry, and what matters on an external terrace is the value with water on it.
How coverage changes it
More pattern, more grip, less clarity. A denser frit gives better slip resistance and passes less light, so the specification is a balance between the terrace and the room beneath.
What that costs in light is on can you see through a walk on rooflight.
The trade off in practice
Usually resolved in favour of grip.
The light lost to a good anti slip pattern is modest, and the consequence of getting the slip specification wrong is somebody falling.
Where it matters most
A terrace used in bare feet.
A domestic balcony is walked on wet, in flip flops, by children running, and that is a more demanding case than a maintenance walkway.
Frost and ice
The condition no surface fully solves.
Glass ices like any other hard surface, and a frozen panel wants the same caution as frozen paving, whatever its slip rating is.
Algae and green film
What actually ruins a good surface.
A shaded panel grows a film of algae that is extremely slippery when wet, and it can make a well specified surface behave like plain glass.
Where that happens
North facing and shaded terraces.
A panel that stays damp and gets little sun grows a film faster, and on a Sussex terrace under trees it wants attention several times a year.
Cleaning it
The whole of the maintenance.
Washing the surface removes the film and restores the grip, and it is done more often than an ordinary rooflight would need.
How is on how do you clean a walk on rooflight.
What not to clean it with
Anything that leaves a residue.
A polish, a wax or a detergent left unrinsed leaves a film that is exactly what you were trying to remove.
Standing water on the panel
A drainage question rather than a glass one.
Water that sits on the surface both encourages algae and makes the panel slippery for longer after rain, and the fall and the channel around it are what fix that.
Matching the surrounding paving
Worth thinking about.
A terrace where the glass grips noticeably differently from the paving around it is a trip hazard of a different kind, and matching the character is sensible.
Grit and shoes
The other side of a textured surface.
A pattern that grips well also holds grit, and grit underfoot is what scratches the sacrificial layer over the years.
What that layer is for is on what happens if walk on glass breaks.
Whether it can be added later
Not properly.
A fired or etched finish is part of the glass, so it is specified at order, and applied treatments on an existing panel are a temporary measure.
What a fall does to somebody
The reason this is worth specifying carefully.
A slip on a terrace is a fall onto a hard surface, often near an edge with a balustrade, and it is the likeliest injury a walk on installation will ever cause.
The structural safety gets all the attention and this is the risk that is real day to day.
Barefoot against shoes
Different surfaces suit each. A coarse texture that grips a shoe can be uncomfortable barefoot, and on a domestic terrace where people go out without shoes that is worth raising before ordering.
Where the sun dries it quickly
A south facing terrace is easier. A panel in full sun dries within minutes of rain stopping and grows very little film, where a shaded north facing one stays damp and needs more attention.
What we specify as standard on walk on glass
We specify the anti slip finish from the wet test value rather than from how it looks in a brochure, and we design the drainage so the panel is not holding water in the first place.
The whole picture is on the walk on rooflight installation page.
Thinking about this job? We survey across Worthing, West Sussex and the South Downs and give you a fixed price before any work starts, with a 10-year workmanship guarantee.