Professional facade cleaning by drone

The exact figure depends on the facade geometry and the level of soiling, but we are typically talking about a 5–10x speed advantage, because no scaffolding or rope rigging is required.

Our technology operates routinely and safely at heights above 120 metres. The exact reachable height also depends on the facade geometry, wind conditions and on-site circumstances, which we clarify during the assessment.

Ideally dry, stable weather. In strong wind, rain, frost or snow we postpone the work for safety reasons and agree on a new date.

We treat glass curtain walls, coated metal and aluminium panels, painted surfaces as well as stone and concrete — the method is always adapted to the surface, and on sensitive surfaces we start with a test patch.

Not by default — we use only osmosis-treated, 0 ppm water, which cleans without chemicals and leaves no spots or streaks. For heavier soiling (e.g. graffiti, industrial grease and soot deposits) we use biodegradable, surface- and environment-friendly products from one of Europe's leading cleaning-chemical manufacturers, which can be properly discharged into the sewer system after use.

The ground safety zone is 3–4 metres wide, measured from the facade, and we only ever cordon off the area directly below the drone. The zone moves along in sections as the work progresses, so only the area in front of one facade section is closed at any time — just as with rope-access cleaning. Two people work per drone: one pilot flies the drone, the other is responsible for securing the cordoned area and handling the hoses safely. We separate the work area from pedestrian traffic with warning signs, cones and marker poles.

That depends on the building's location: it typically affects a section of the pavement and rarely the carriageway. If necessary, we consult the local authority and obtain the required permits ourselves. On busier sections we choose, where possible, a time when pedestrian traffic is at a minimum.

The drone has a gimbal camera that helps the pilot navigate and check the condition of the cleaned surface. We do not record any images or video during the operation: the live view appears only on the pilot's display, is not stored and is not transmitted.

The camera's field of view and use are directed at checking the nearby facade surface; it is neither suited nor intended for observing the inside of offices or the people in them. Since no data is recorded, no personal data is processed either. On request we also confirm this in a duly signed declaration.

The maximum water pressure at the pump on the ground is 160 bar. The pressure is regulated and limited at the ground unit and drops further along the hose up to the drone. The drone can work from a distance of 2–3 metres from the glass, so it stays at a safe distance from the building and the direct pressure on the seals is significantly lower.

We work with spray nozzles of different spray angles and always choose the right one for the given surface. Before the work we consult the building operator about the characteristics of the facade and windows and any known defects, and adapt the equipment and technology to them. At the pump we reduce the pressure where necessary.

If damage or water ingress should nevertheless occur during cleaning, we stop work immediately and document the damage on site. We notify the client without delay and report the claim to our insurer. We hold full liability insurance as required. We send the insurance documentation on request.

In our experience it can be carried out routinely and safely if the weather is suitable (wind speed including gusts of at most 8–10 m/s, and no precipitation); water and power supply are available on site, and access and placement of the equipment is resolved; and the annual schedule of official permits and public-space closures can be planned in advance, which considerably simplifies the procedure for recurring work. Surfaces the drone cannot reach (e.g. rear, concealed parts, lifts, recesses) are cleaned by our rope-access colleagues, so the whole facade can be completed in one go. The larger and more continuous the surface to be cleaned, the better the technology performs.