Window cleaning at height: cherry picker, BMU gondola, rope access or drone?
Team OPPY4 min read
High-rise window cleaning uses one of four methods: an aerial work platform (cherry picker), a gondola on a permanent rooftop installation (BMU), rope access or a drone. The choice depends on the ground around the building, the roof, the shape of the glazing and the weather. With every method except the drone, someone works at height.
Glass that a window cleaner with a water-fed pole can no longer reach needs a different approach. There are four common methods: an aerial work platform, a gondola hanging from a permanent rooftop installation, rope access and a drone. Here is what to know before you choose.
Which rules apply to window cleaning at height in Belgium?
In Belgium, work at height falls under book IV, title 5 of the Code of well-being at work. These rules give collective protection priority over personal protection and only allow work at height when the weather does not put workers at risk.
According to the Federal Public Service Employment, the employer carries out a risk assessment, chooses the most suitable work equipment and provides fall protection where needed (FPS Employment). These rules cover the three methods in which a window cleaner works at height.
What does window cleaning from a cherry picker need from your building?
An aerial work platform, or cherry picker, needs ground that can take the load and space at the foot of the facade. The window cleaner stands in a basket that the machine brings up to the glass.
According to IPAF, the international federation for powered access, a car tyre exerts about 2.4 bar, while an outrigger without a spreader pad may exceed 13.8 bar. IPAF therefore calls for a ground assessment before every set-up and warns about cellars, sewers, manholes and services under the paving (IPAF). The car park, driveway or pavement where the machine stands must therefore carry its weight and cannot be used while the work is going on. If the machine is on the public road, a permit is sometimes needed.
According to IPAF, an outdoor-rated platform typically has a maximum wind rating of 12.5 m/s, measured at the platform, and the wind at height can be stronger than on the ground (IPAF). A glass canopy, an atrium or a rooflight is only within reach if the machine can get close enough.
How does a BMU window cleaning system work?
A gondola hangs from a BMU (building maintenance unit), a permanent rooftop installation that lowers it down the facade. The window cleaner stands in the gondola and works across the facade one drop at a time.
Little is needed at ground level: only the area below the gondola is cordoned off. The installation does have to be planned into the design of the building, and it needs maintenance and inspection of its own. The European standard EN 1808 sets the safety requirements for suspended access equipment, permanent and temporary, covering design calculations, stability criteria, examinations and tests. It also covers the rails and the fixings to the building structure (BSI).
Glass outside the facade the gondola was designed for, such as a canopy over the entrance, an atrium or a glass roof, is usually out of its reach.
When is rope access allowed for window cleaning?
In Belgium, rope access, with window cleaners abseiling down the facade, is prohibited in principle for systematic or repetitive work. It is allowed only when the risk assessment shows that safer equipment is impossible or more dangerous, or when setting that equipment up carries more risk than the work itself.
Where rope access is allowed, the Code sets strict conditions. The system has at least two separately anchored lines, a working line and a safety line, and the worker wears a harness connected to a mobile fall arrester that follows their movements. Nobody works alone, the workers receive specific training that includes rescue, and a competent person supervises (articles IV.5-16 to IV.5-18 of the Code). The roof needs anchor points that are strong enough. Sloping or horizontal glass, such as an atrium, is often awkward to reach on ropes.
What can a drone do, and where does it stop?
With a drone, nobody works at height: the pilot stays on the ground and the drone carries the water to the glass. It also reaches canopies, atriums and glass roofs, but it has clear limits.
Because a cleaning drone sprays, it falls under the specific category. The Belgian FPS Mobility and Transport lists dispersing products as an example, and the operator then needs a declaration under a standard scenario or an operational authorisation (FPS Mobility and Transport).
A drone does not fly in rain or strong wind. It only cleans the outside of the glass. Heavy crusts often need close-up work, and trees or cables right next to the facade can make a flight difficult. How a drone works in detail is explained in how drone window cleaning works.
Four methods for window cleaning at height
| Aerial work platform | Gondola (BMU) | Rope access | Drone | |
|---|---|---|---|---|
| What the building needs | Ground that takes the load and room for the machine | A permanent rooftop installation, planned into the design | Strong anchor points on the roof | A clear area at the foot of the facade |
| Disruption on the ground | Car park, driveway or pavement occupied, sometimes a permit | A cordoned-off area below the gondola | A cordoned-off area below the work position | A safety perimeter that moves along with the work |
| Canopies, atriums and glass roofs | Only if the machine can get close enough | Usually not | Often awkward | Reachable from the air |
| Weather | Within the machine's wind rating, typically 12.5 m/s for outdoor use | Only when the weather does not put workers at risk | Only when the weather does not put workers at risk | Not in rain or strong wind |
| Rules | Belgian work-at-height code and a ground assessment | Belgian work-at-height code, EN 1808, maintenance and inspection of the installation | Prohibited in principle for systematic work, with strict exceptions | Specific category, with a declaration or operational authorisation |
How do you compare quotes for high-rise window cleaning?
Compare the full set-up of each visit: the machines, the permits, the closures and the time during which part of the building cannot be used.
With an aerial work platform, that includes transporting the machine, occupying the car park or street and sometimes a permit, and it comes back at every visit. With a gondola, the maintenance and inspection of the installation count. With rope access, ask for the risk assessment that justifies it. With a drone, ask under which declaration or authorisation the operator flies and how they reschedule when the weather turns.
How we do it at OPPY
We clean glass facades, windows, glass canopies and atriums with technology controlled from the ground, such as drones and robotics, choosing the most efficient approach for each building. During a site visit or a remote assessment we look at the glass, the frames, the access and where the safety perimeter will go. We prepare the authorisation file for the specific category.
We clean glass with purified water at low pressure, so seals and frames are not put under strain, and can then apply a dirt-repellent coating. On facades, we choose per surface between softwash at low pressure and high pressure up to 200 bar. In rain or strong wind we don't fly and agree a new date with you. The inside of the windows stays with your regular window cleaner, and we can align our schedules. The report with before and after photos is then on the OPPY platform. For more on glass at height, see Window cleaning.
Sources
- Tijdelijke werkzaamheden op hoogten (temporary work at height, in Dutch), FPS Employment, Labour and Social Dialogue, Belgium
- Code of well-being at work, book IV, title 5: work equipment for temporary work at height (in Dutch), FPS Employment, Labour and Social Dialogue, Belgium
- Safe use of MEWPs: guidance on the assessment of ground conditions, IPAF
- Wind rating guidance for MEWPs, IPAF
- BS EN 1808:2015, Safety requirements for suspended access equipment, BSI
- Categorie SPECIFIC (in Dutch), FPS Mobility and Transport, Belgium
Frequently asked questions
Is rope access allowed for window cleaning in Belgium?
For work at height that is systematic or repetitive, rope access is prohibited in principle. It is allowed only when the risk assessment shows that safer equipment is impossible or more dangerous, or when setting that equipment up carries more risk than the work itself. Strict conditions then apply, such as two separately anchored lines and never a worker on their own.
Do you need a permit to put a cherry picker on the street?
Sometimes. If the machine stands on the public road or the pavement, a permit to occupy it is sometimes needed. Check with the local authority and agree with the contractor who applies for it.
Up to what wind speed can an aerial work platform operate?
The limit is on the machine's data plate. According to IPAF, an outdoor-rated aerial work platform typically has a maximum wind rating of 12.5 m/s, measured at the platform. A machine rated for indoor use only must not be used where there is wind. At height, the wind can be stronger than on the ground.
Can a drone replace a BMU gondola?
For the outside of the glass, a drone can be an alternative, including for canopies and atriums a gondola cannot reach. It does not fly in rain or strong wind, and it does not clean the inside. A building with a BMU can also combine the two methods.
About the author
Team OPPY
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