How do you clean a walk-on rooflight?
Warm water and a soft brush, two or three times a year. Algae is the thing to stay ahead of.
Part of our Walk-On Rooflight Installation guide
Straightforward, and the frit tolerates more robust cleaning than a coated rooflight would.
The top surface
Warm water, mild detergent, a soft brush. The textured frit holds dirt in the pattern, so a brush does more than a cloth.
Rinse thoroughly. Detergent left in the texture attracts dirt back.
Two or three times a year, more in a shaded or wooded position.
Algae is the real issue
In a shaded damp position, algae builds on the surface and it is genuinely slippery regardless of the frit beneath. That is the main way a walk-on surface becomes less safe over time.
Regular cleaning prevents it. A proprietary algae treatment suitable for glass deals with an established growth; strong bleach does not belong near the frame seals.
The underside
Often forgotten and it is what people in the room actually see. Dust settles on the underside of any overhead glazing.
Access is worth thinking about at design stage: a panel over a stairwell is much harder to reach from below than one over a hallway.
The drainage channel
Clear it at the same time. A blocked perimeter channel holds water against the unit and is worse than no channel at all.
Under trees, twice a year at least.
What to avoid
Strong solvents and abrasives, which attack the frame finish and sealant rather than the glass. Pressure washing directly at the frame junction. And walking on it in gritty footwear straight after cleaning.
Water and a soft brush
The top surface of a walk on rooflight carries an anti slip treatment, either a ceramic frit fired into the glass or an etched pattern. It is a wearing surface, and how you clean it decides how long it lasts.
Warm water, a mild detergent and a soft brush or a microfibre mop. Rinse thoroughly. That is the whole method and it takes minutes.
What not to use
Wire brushes and scouring pads. They abrade the anti slip layer, which is the thing keeping the surface safe underfoot in the rain.
Pressure washers at close range. The jet damages the anti slip treatment and, more seriously, drives water into the perimeter seal. On a flush unit that seal is the whole defence against water ingress.
Solvents and abrasive creams. They attack the frit and any coating.
Steam. Thermal shock on a laminated build up is not worth risking.
The perimeter matters more than the glass
The single most important maintenance job on a walk on rooflight is not cleaning the pane. It is keeping the perimeter drainage channel clear.
A walk on unit sits flush with the surrounding surface, because a raised kerb in the middle of a terrace is a trip hazard. That means the usual defence against standing water is gone, and the design relies on a channel around the perimeter carrying water away to an outlet.
Leaves and silt collect in that channel. A blocked channel is a pond sitting against the seal, and that is what causes trouble. Clear it twice a year on a plot with trees and annually otherwise, and check that the outlet it discharges into is actually running.
Keep grit off it
Grit underfoot is what actually abrades an anti slip surface, more than any cleaning method does. A doormat at the door onto the terrace does more for the life of the unit than anything else on this page.
The same applies to garden work: sweeping soil or gravel across the pane repeatedly will dull it.
The face below the glass
Usually the easy part, because it is inside. Ordinary glass cleaner and a soft cloth.
Where the unit is above a stairwell or a double height space, plan the access before you need it. A pole system with a soft head works; leaning a ladder against a glass floor from below does not.
What to look for while you are up there
Any chip or scratch to the top ply, which on a laminated build up is not an immediate safety problem but is worth reporting. Any sign of movement or gapping at the perimeter seal. Any water sitting rather than draining.
Catching those early costs nothing.
How often
The glass as often as it looks dirty, which on a terrace in use is likely to be monthly in summer. The perimeter drainage channel twice a year on a plot with trees and annually otherwise, which matters far more.
A blocked channel is a pond sitting against a seal, and on a flush unit that seal is the whole defence against water ingress.
Ask us
If the anti slip surface has been damaged or the perimeter drainage is not clearing, send a photograph. Some of that is repairable and some is not, and we will tell you which honestly.
What to avoid putting on it
A heavy planter or a furniture leg left in one place. A point load concentrated on a single spot is a different loading case from a person walking across, and the specification was written for the second one. If something heavy has to sit on the terrace permanently, say so before the unit is specified rather than afterwards.
One last point
A doormat at the door onto the terrace does more for the life of the anti slip surface than any cleaning method will, because grit underfoot is what actually abrades it.
Little and often, because grit is the enemy
The purpose of cleaning a walk on unit is not appearance, it is protection. Grit carried onto the surface on shoes gets ground into the glass by foot traffic, and accumulated fine scratches turn a clear pane into a hazed one.
So sweeping or rinsing the grit off regularly does more for the unit than a thorough clean twice a year.
The method
Rinse first with plenty of water to float the grit away before anything touches the glass. Then warm water with a little washing up liquid and a soft brush or microfibre. Rinse again and let it dry.
On a fritted surface, work the brush into the texture, because that is where organic film collects.
Products to keep away from it
No abrasive pads, which cause exactly the damage you are cleaning to prevent.
No aggressive chemicals near the perimeter seal.
No pressure washer aimed at the joint, which forces water into a detail designed to shed rather than resist it.
Algae
On a shaded terrace, organic film builds up and is far more slippery than the glass itself. That is a safety matter rather than a cosmetic one, and it is the main reason to clean a shaded unit on a schedule.
While you are there, clear the perimeter drainage channel. That is what prevents leaks.
More on Walk-On Rooflight Installation
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