How CoxGomyl achieved full façade coverage on a segmented sloped roof at the 172.2-metre Hangzhou Binjiang Science and Innovation Building without disturbing the building’s architectural lines.
Rising 172.2 metres above Hangzhou’s Binjiang district, one of the focal points of China’s digital economy and high-tech industry, the Hangzhou Binjiang Science and Innovation Building is a statement of the city’s forward-looking ambitions. Yet behind its sculpted, sloping roofline lies an equally ambitious piece of engineering: a building maintenance unit (BMU) that keeps every panel of the façade within reach, while staying completely out of sight when it is not in use. For CoxGomyl, part of Alimak Group’s Facade Access Solutions, the project marked a genuine first.
Most high-rise façades can be serviced by a roof-mounted machine running along a level track. Hangzhou Binjiang offered no such convenience. Its roof is segmented and pitched across several gradients, and the design team was firm that any maintenance equipment must never break the clean silhouette they had created. The brief was demanding in its simplicity: reach 100% of the façade across a multi-level sloped roof, and vanish from view the moment the work is finished.
The solution was a purpose-built BMU able to climb the pitch of the roof itself, the first inclined climbing system CoxGomyl has ever delivered. Instead of imposing a flat track onto a sloped structure, the engineering team designed the machine to follow the roof’s natural geometry, moving smoothly between gradients as it carries its cradle to every section of the elevation. A bespoke track layout brings the concept together, combining three inclined climbing sections with two horizontal platforms so the unit can transition seamlessly from slope to level and back again.
The custom-engineered BMU was dimensioned to satisfy both the building’s maintenance demands and its architectural vision.
| Specification | Detail |
|---|---|
| Building height | 172.2 m |
| Track configuration | 3 inclined climbing sections + 2 horizontal platforms |
| Maximum outreach | 15.2 m |
| GHU (gantry hoist unit) capacity | 400 kg |
| Drive system | 4 drive motors |
| Façade coverage | 100% |
| Parked profile | Fully concealed from view |
Working on an incline places unusual demands on a maintenance machine. To keep every movement controlled and predictable, the unit runs on four drive motors that spread traction and reinforce stability throughout the climb. An advanced climbing mechanism adds autonomous load balancing, continuously adjusting to keep the platform level and secure as it negotiates the shifting roof profile. Together these features give operators confidence on a structure where a standard system simply could not perform.
Large BMUs are usually hoisted into position by tower crane, a method that adds cost, extends the programme and complicates logistics on a busy site. For Hangzhou Binjiang, the team developed a tower-crane-free installation strategy, sequencing assembly so the system could be positioned and commissioned without that dependency. The approach reduced disruption and demonstrated how thoughtful planning can de-risk even the most complex installations.
The finished installation delivers precisely what the brief called for. Every part of the façade can be reached safely and reliably for cleaning and maintenance, while the BMU withdraws from sight when parked, preserving the building’s intended appearance. Designed, manufactured, installed and commissioned by CoxGomyl’s regional team in China, the project shows how bespoke engineering can resolve the toughest access challenges without asking the architecture to compromise — turning a difficult roofline into a showcase of what purpose-built façade access can achieve.
Facade Access Solutions, part of Alimak Group, designs, manufactures, installs and services building maintenance units (BMUs) and permanent façade access systems for landmark buildings around the world, through brands including CoxGomyl. To discuss an access challenge on your project, get in touch with our team.
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