Slip Resistance and Glass for Walk-On Rooflights

There are three common ways to give walk-on glass its grip. Each is applied to the top face of the upper pane.

• Acid etching a chemical treatment that gives the surface a fine, frosted texture
• Sandblasting a stream of grit that roughens the surface in a plain or patterned finish
• Ceramic frit small dots or lines of ceramic enamel fired onto the glass, giving a raised, gripping pattern
• Anti-slip coating a clear applied layer with a textured feel

Etching gives an even, soft look, and it is easy to keep clean. Sandblasting can carry a pattern, such as a band of lines, which also hides footprints. Ceramic frit gives the most positive grip, and the dots can be spaced so most of the glass stays clear. A coating can suit an indoor panel but wears sooner, so it is rarely the choice for a terrace.

Texture also changes how a panel looks from below. Etched glass diffuses the view, so people in the room beneath see a soft brightness, not a clear window onto the sky and the soles above. A patterned frit shows as a scatter of fine marks against the daylight. Some owners like that, and some prefer the plainest finish that still grips, so we show both from underneath at the survey.

The right answer is seldom the same for two panels. A glass floor over a basement stairwell may favour clarity and a gentle texture, while a terrace panel that is rained on needs a firmer grip.

Claims about grip mean little without a test behind them. Two methods turn up most often on data sheets.

The pendulum test swings a rubber slider across the surface and records how much it is slowed. It can be run wet or dry, and the result is given as a pendulum test value, where a higher value means more grip. The ramp test places a tester in boots on a tilting surface, coated in oil or water, and the angle at which they slip gives a rating on an R scale. A higher R figure means a rougher surface.

The two do not translate neatly into each other, and the results apply to that finish on that glass, tested in a lab. When a maker quotes a figure, ask which test it comes from and whether it was run wet. A dry result for a terrace panel tells you very little.

Test results are only as good as the conditions behind them. Ask for the surface to be tested in the finish that will be supplied, not a sample of a similar one, and ask whether it was tested new or after wear. A figure measured on a pristine sample can fall as the top layer scuffs over the years.

An indoor panel meets dry soles and the occasional spill. An outdoor one meets rain, frost, algae, leaves and grit, so the finish has to work harder.

Indoors, a fine etch or a light sandblast is usually plenty. The panel is protected from weather, and socks, slippers and clean shoes do not demand a lot. A hallway or landing panel that lights a basement tends to sit here.

Outdoors, frit patterns and heavier textures come into their own. On a roof terrace the panel is a floor like the rest of the deck, and it needs to behave like it. Our roof terrace guide is the place for the surroundings, and the finish chosen for the glass should match the grip of the decking beside it so nobody notices a change underfoot.

Cleaning access matters outdoors. A panel in the middle of a large terrace is hard to reach with a brush, and one placed near the door is easy. It sounds minor, but a surface that is never cleaned is a surface that stops gripping, so the position of the panel is part of the safety plan.

North-facing and shaded panels need an extra thought. Damp lingers and green growth takes hold, which makes any finish slippery. A texture that is easy to brush clean is more valuable there than a very fine one.

Slip resistance is about the top face, but the glass beneath decides how long that face lasts and how safe the panel stays if it is damaged. The glass in these panels is laminated, meaning panes bonded together with interlayers. If the top layer is scuffed or chipped, the layers beneath hold the panel together.

The top pane is usually the sacrificial one. It takes the wear, the grit and the scratches, and the treated surface lives on it. If it wears out, it can be replaced without touching the structural layers below. That is another reason the finish matters: a tough, well-bonded texture lasts longer than a thin one.

The other layers are chosen for strength. Their thickness depends on the size of the panel and the load it carries; our pages on walk-on rooflight glass thickness and load ratings explain how. A house roof does not legally need laminated glass under Part K, yet for a panel you stand on it is the build we specify, because it is the sensible way to make a glass floor.

The edges deserve a look as well. Where the glass meets the surrounding floor or kerb, the joint should be level or very nearly so, because a raised lip is a trip point whatever the finish. Flush fitting is the aim, and we plan the build-up so the floor finish and the glass top sit at the same height.

Heat treatment matters too. Toughened glass resists impact and load far better than ordinary glass, and most structural layers in a walk-on build use it or heat-strengthened glass.

The finish only does half the work. The other half is what is on the sole. Rubber trainers grip a textured panel well. Smooth leather soles, wet wellingtons caked in mud and bare wet feet after a swim behave quite differently. A glass floor in a house where people come in from the garden needs a firmer finish than one in a quiet upstairs corridor.

Think about the people as well. Children run and skid. Older relatives take shorter, more careful steps and may rely on a handrail or the wall for balance. A panel in the middle of a hall is a different proposition from one beside a wall. Dogs have claws and no grip control at all, and a panel they cross at speed should have a defined texture, not a barely frosted one.

None of this means a glass floor is a bad idea. It means the finish is chosen for the household. At the survey we ask who lives there, then suggest a finish that suits them, and say which options we would avoid.

A finish that grips on day one can lose its edge if it is neglected. A few habits keep it working.

Season by season, the routine is light. A quick sweep and rinse in spring clears winter growth, and another in autumn lifts the leaf fall before it stains. Those two sessions are enough for most panels, with a brush in between if the weather has been wet and the panel sits in shade.

Use clean water and a soft brush or sponge. Mild washing-up liquid is enough for most marks, and a rinse afterwards stops film building up. Avoid wax, polish and anything marketed as a shine. They leave a smooth film over a textured surface and undo the finish. Abrasive pads and harsh chemicals can damage the top layer, so leave them in the cupboard.

Outdoors, sweep leaves and grit away before they grind in. In autumn and winter, check shaded panels for green growth, and clean it off before it becomes a slick film. A pressure washer is a blunt tool for glass; a brush is kinder and does the job.

Indoors, wipe up spills at once, particularly oil. If a panel in a kitchen or hall is walked on in socks, a small mat at the edge keeps grit from reaching it.

At the free survey we ask where the panel sits, who walks on it and in what footwear. Children, older relatives and the dog all count. From that we suggest a finish and show a sample so you can feel the texture, not just read about it.

The written, itemised quote names the finish and the glass build-up, so two quotes can be compared line by line. If the panel is part of a bigger scheme, such as a basement conversion, the page on walk-on rooflights for basements shows how the pieces fit. For the price effect of one finish over another, see the walk-on rooflight cost guide and our costs page.

One crew handles the whole job, and the weather is kept out of the house when each day closes. Our guarantee covers workmanship for ten years. We call at your home, from Bristol and Bath out to the surrounding towns, so there is no showroom to visit. Every guide in this set is listed on the walk-on rooflight hub.