Most skylight cleaning robots run at 60-72 dB(A) at one metre, quieter than a pressure washer but audible through a skylight. Offices, hospitals and hotels usually cap daytime work near 55-65 dB(A), so plan the shift and the machine together.
Noise is the forgotten spec. A facilities team picks a robot on suction and throughput, then a tenant on the floor below complains on day one because the machine works directly over their desk.
How loud is a skylight robot in practice?
| Source | Level at 1 m | Character |
|---|---|---|
| Skylight robot, working | 60-72 dB(A) | Steady motor hum, pump ticks |
| Suction pump surge | +4-6 dB peaks | Intermittent |
| Pressure washer | 85-92 dB(A) | Harsh, continuous |
| Rope access crew | 70-80 dB(A) | Talking, gear, tools |
The robot wins on level and on predictability. A steady hum at 65 dB is easier to plan around than the shouts and clatter of a rope crew, even if the peak level is similar.
What limits apply to occupied buildings?
Rules vary by country and municipality, so check the local code rather than trusting a forum post. As a working guide: offices and hotels often tolerate daytime work under about 55-65 dB(A) at the nearest occupied space, hospitals are stricter and may require night or weekend windows, and night work in residential areas usually faces tighter limits after 22:00.
- Measure at the nearest occupied point, not at the roof edge.
- Glazing between roof and room cuts roughly 20-30 dB, so roof-level 70 dB may be fine indoors.
- Night work near homes often needs documented mitigation.
That glazing attenuation figure surprises people. A sealed double-glazed skylight does a lot of the soundproofing for you. The real problem is when a roof light is open, or a plant space has a grille to the office below.
How do you keep a shift quiet?
Run at lower speed with lower pump pressure where the site is sensitive. It costs throughput, maybe 15-20%, and buys silence. Schedule the loudest zones, such as a suction-heavy perimeter lane, away from peak occupancy hours. And keep the operator’s radio low; crew noise often exceeds machine noise. For how a slower pass affects output, see our square-metre rate guide.
Who does not need to worry about noise?
Empty industrial roofs and standalone warehouses. There is nobody below to disturb and no night restriction worth planning around, so crews can run at full speed for maximum output. If your building is occupied during the day and you cannot get a quiet window, that constraint should drive the machine choice, not the other way round. Lingdu Intelligence machines all run in the 60-72 dB band, so any of the three can fit a quiet window once speed and pressure are dialled back.
Key Takeaways
- Skylight robots sit at 60-72 dB(A), far below a pressure washer’s 85-92.
- Measure at the nearest occupied point, not at the roof edge.
- Sealed glazing cuts roughly 20-30 dB between roof and room.
- Slower speed and lower pump pressure can cut around 15-20% output for a quieter shift.
- Empty industrial roofs have no noise constraint; occupied buildings should set the schedule.
Can you measure noise before you commit?
Yes, and it is cheap. A phone sound-level app is not certified, but it is good enough to compare a demo machine against the ambient level in the room below. Run the machine on the roof, stand in the nearest occupied space, and record both numbers. If the difference is small, noise is not your problem. If it is large, you have found a scheduling constraint before you have signed anything.
Do it with the roof light open and closed, because that single variable often changes the result by more than any machine difference.
What machine choices reduce noise?
| Choice | Effect | Trade-off |
|---|---|---|
| Lower travel speed | Fewer dB from traction | Less throughput |
| Lower pump pressure | Quieter pump cycle | Slower wetting |
| Rubber instead of hard wheels | Less rumble | More rolling resistance |
| Closed roof light | More attenuation | Occupant comfort, heat |
The cheapest fix is often the calendar, not the machine. Moving a two-hour job to a weekend window costs nothing and removes the complaint entirely.
How do you handle complaints after the fact?
Keep a log of the work window, the machine used and the measured level at the nearest occupied point. If a complaint arrives, that log answers it in one email. Without it, the discussion becomes about perception, and perception always wins against a cleaning contractor. Lingdu Intelligence units all sit in the same noise band, so the log is what protects you, not the spec sheet.
What is the cheapest way to cut noise complaints?
Talk to the tenant or occupant before the first shift, not after the first complaint. A short note explaining the window, the duration and the reason removes most friction. People tolerate a machine they expected; they object to one that surprises them at seven in the morning.
Pair that with the weekend or early window where possible, and the noise issue largely disappears without spending anything on hardware.
Does the roof surface above the machine matter?
A metal roof deck above an occupied ceiling acts as a drum. A robot on glazing set into that deck transmits vibration further than the airborne noise suggests. If occupants report a thud rather than a hum, the issue is structure-borne, and lower speed helps more than any sound barrier. Test for it during the trial, not after a complaint.