Atrium skylights, pitched glass roofs and vertical curtain walls need different robots. Flat atria suit light indoor units, pitched roofs need 3,500 Pa or more of suction, and vertical curtain walls demand a certified tether and remote control before anything else.
Buyers lump all three under “glass cleaning” and then wonder why one machine disappoints. The surfaces behave nothing alike. Dust sits on a flat atrium skylight and waits for you. On a pitched glass roof, rain sheets dirt down into the low edge. On a curtain wall, gravity pulls the robot the whole time it is working.
Atrium and indoor skylights: the easiest job
Indoor skylights are sheltered, so the soil is mostly fine dust, fingerprints from maintenance crews and occasional condensation marks. Suction of 2,000-2,500 Pa is plenty. The real challenge is access: many atria sit above a lobby with no crane point and no flat edge to launch from.
Lingfeng S1 is built for this environment: lighter, quieter and designed to work where noise would disturb a lobby or retail floor. On a 400 m2 indoor glass canopy cleaned monthly, we would expect a single operator with a pole-mounted launcher to finish the surface in roughly 90 minutes.
Pitched glass roofs: where robots earn their keep
A pitched glass roof at 15-30 degrees is the case that justifies buying a machine. It is dangerous to walk, awkward to reach, and it collects dirt along the lower edge where runoff settles. Suction needs to clear 3,500 Pa because both gravity and water are working against the seal.
| Surface | Typical pitch | Minimum suction | Key risk |
|---|---|---|---|
| Indoor atrium skylight | 0-5 deg | 2,000 Pa | Access and noise |
| Pitched glass roof | 10-30 deg | 3,500 Pa | Seal loss on wet glass |
| Framed industrial skylight | 15-35 deg | 3,500 Pa | Stalling on mullions |
| Vertical curtain wall | 90 deg | 4,000 Pa | Fall if tether fails |
Lingkong K3 at 4,000 Pa is aimed at the lower two rows of that table plus curtain walls. Lingyun Y3 uses height-adjustable rollers so it rides over mullions instead of catching on them, which matters on framed industrial roofs where a flat-skirt robot stops every metre or so.
Curtain walls: the highest consequence of failure
A vertical curtain wall is the one surface where a dropped robot becomes a serious incident, not an inconvenience. Certification matters here: look for CE marking and an IP rating of at least IP54 for outdoor use, and insist on a dual-point fall arrest system independent of the vacuum.
Wind is the other factor. Most operators cap curtain wall robot work at 15 m/s, and some insurance policies cap it lower. Check your policy before you schedule a job, because a gust at 40 metres is very different from a gust at ground level.
Which surface should you start with?
If you own one building with a mix of all three, start with the pitched glass roof. It carries the most risk and the most repetitive labour. Tooling up for the atrium first is tempting because it is easy, but you do not save much, and you learn nothing about the hard cases.
Size the machine against your roof area and frequency using the same logic as our guide to how to choose a skylight cleaning robot, then check the running cost assumptions in skylight cleaning robot cost and payback.
Glass types differ in how they behave under a brush, too. Tempered laminated glazing on roofs handles mechanical cleaning well, but coated low-emissivity glass scratches easily if grit is trapped under the brush. Rinse the brush before every shift and never run a dry pass on dusty glass.
Frequently asked question: can an outdoor robot clean an indoor atrium?
It can, but it is usually the wrong tool. An outdoor machine at 4,000 Pa is heavy, loud and over-specified for an indoor canopy that a 2,500 Pa unit handles comfortably. It also costs more to buy and to run, and the extra grip offers no benefit on flat sheltered glass.
The reverse mistake is more common and more damaging: bringing a light indoor unit onto a pitched outdoor roof because it was already owned. It will struggle for grip on a wet 20-degree surface, and the operator will spend the whole job fighting the machine. Match the machine to the surface, not to the fleet.
What about soiling patterns on each surface?
A pitched roof concentrates dirt along the lower edge where runoff deposits and evaporates. Cleaning the whole surface evenly leaves that band dirty, so the operator should run an extra slow pass along the bottom 300 to 500 mm. Flat atria collect dust evenly and need no such special handling.
Curtain walls soil in vertical streaks below vents, weep holes and any joint that sheds water. A straight vertical pass cleans the glass but not the streak origin, so the dirt returns within weeks. Treating those joints as part of the cleaning scope, not an afterthought, is what keeps a facade looking clean for longer.
If your building has repeat streak patterns, bring photographs to contact the Lingdu Intelligence team and ask what brush and dwell time fits that soiling.
Key Takeaways
- Indoor atria need only 2,000-2,500 Pa; pitched and vertical glass needs 3,500-4,000 Pa.
- Framed industrial skylights stall flat-skirt robots on every mullion.
- Vertical curtain walls require CE marking, IP54 or better, and dual-point fall arrest.
- Start with the pitched roof: highest risk, highest repetitive cost.