Drone Cleaning vs Gondola
The comparison turns almost entirely on one question: does your building already have a certified building maintenance unit on the roof?
Drone cleaning usually beats gondola work on a one-off clean, because gondola access carries days of rigging and certification before any cleaning starts. But if your tower already has a certified building maintenance unit (BMU) installed on the roof, most of that setup cost disappears and the two methods become genuinely competitive.
Key takeaways
- No BMU installed → drone wins clearly; rigging temporary access is the dominant cost.
- Certified BMU already installed → gondola is competitive; compare on disruption and speed instead.
- Contact work needed → gondola, every time. A drone cannot touch the building.
- Occupied floors → drone; a cradle passing windows for days generates complaints.
- Deep recesses and soffits → gondola reaches what a drone cannot.
On this page
The BMU question
Many Singapore commercial towers are designed with a building maintenance unit — a permanently installed roof-mounted davit or cradle system for facade access. Where one exists, is certified and is in service, gondola cleaning starts from a very different cost base than a building where temporary suspended access must be rigged from scratch.
So the first question is not "drone or gondola". It is: do you have a working BMU?
- Yes, certified and in service — gondola cleaning is competitive. Judge on disruption, speed and whether contact work is needed.
- Yes, but lapsed certification — recertification cost may exceed the cleaning. Get that number before comparing.
- No BMU — temporary suspended access or rope must be rigged, and the drone advantage is large.
Side-by-side comparison
| Factor | Drone cleaning | Gondola / BMU |
|---|---|---|
| Setup before cleaning | Hours | Days (none if BMU in service) |
| Coverage rate | 1,500-1,800 sqm/day | Slower, cradle-width passes |
| Workers at height | None | Yes, in the cradle |
| Contact work | Not possible | Full capability |
| Deep recesses / soffits | Cannot reach | Reachable |
| Disruption to occupants | Short window | Cradle at windows for days |
| Wind sensitivity | Flying stops | Cradle also suspends in high wind |
| Lead time | 3-4 weeks (CAAS) | Shorter with BMU in service |
| Ongoing asset cost | None | BMU inspection and maintenance |
Where the gondola cost actually goes
On a building without a BMU, the cleaning is a minority of the invoice. The cost sits in temporary suspended access: engineering the anchor arrangement, mounting and counterweighting, certification and load testing, crew mobilisation, and daily inspection through the works.
All of that is incurred whether the facade is 1,500 sqm or 5,000 sqm, which is why gondola cleaning scales badly downward. A small building pays nearly the same setup as a large one.
Note the symmetry with drones. Drone work also carries a mobilisation floor — around S$2,000 — for the same structural reason. The difference is scale: a drone's fixed cost is measured in hours of setup, a gondola's in days of rigging.
Which to choose
| Situation | Recommended |
|---|---|
| No BMU, one-off clean | Drone |
| Certified BMU in service, routine cycle | Gondola |
| BMU certification lapsed | Drone (compare against recert cost) |
| Cleaning plus sealant or glazing repair | Gondola |
| Occupied floors, disruption sensitive | Drone |
| Heavily recessed or articulated facade | Gondola, or hybrid |
| Deadline inside three weeks | Gondola (CAAS lead time) |
For the rope access comparison, see drone vs rope access. For pole systems, see water-fed pole vs drone.
Frequently asked questions
Is drone cleaning cheaper than gondola cleaning?
Usually yes on a one-off clean, because gondola work carries days of rigging and certification before any cleaning happens. On buildings with a permanent building maintenance unit already installed, the gap narrows considerably.
What is a building maintenance unit?
A building maintenance unit or BMU is the permanently installed roof-mounted cradle system many Singapore towers use for facade access. Where one exists and is certified, gondola cleaning avoids most rigging cost and becomes more competitive.
Can a drone replace a gondola entirely?
For cleaning open elevations, usually. For any work requiring physical contact — glass replacement, sealant repair, gasket work, hands-on inspection — no. A BMU exists for maintenance access, not only cleaning, so it retains its purpose.
Comparing access methods?
Tell us whether your building has a BMU. That single fact usually decides the answer.