Pointed Roofs

pointed-2

Buildings of rectangular shape are relatively easy for access, provided that the roof top is of no obstruction.
Gondola system can be designed and accommodated without much difficulties.

Figure 1 : Operation of curtain wall cleaning

Buildings with pointed roof do not have roof space to accommodate access system at its prism-shaped roof top.
Architects can solve this problem by designing the highest floor to house the trolley unit.
The entire floor slab will be laid with tracks for the unit to glide round the perimeter of the building.
A retractable gate door on each side of the facade is built to launch the gondola.
This can ensure that the gondola system can cover all the surfaces of the external facade

Figure 2 : Telescopic jib

Figure 2 shows the gate door opened with the track-mounted trolley unit equipped with a telescopic arm launching the window cleaning gondola.

Wheelock Place

Figure 1 : Wheelock Place

Wheelock Place consists of an office tower and a podium block.
It can be observed that there is a gap between the roof and the external façade.
Inside this gap, a permanent trolley unit is stored for the regular cleaning of the glass curtain wall. (Figure 3)
It is important that the gap designed is high enough for the gondola cage to be extended out of the gap (about 2m high together with the height of the jib).

Figure 2 : Rotating ladders on glass cone

For the sharp cone-shaped glass roof structure at the entrance of the podium block, it is impossible to use the normal gondola system, which hangs down from roof top, to clean this feature.
The only method of access is by using rotating ladder mounted on the track around the external circumferences of the cone.

Figure 3 : Metal dome-shaped roof at Office Tower

For the dome-shaped metal roof structure at the office tower, there is no provision of track ladder system.
The only way to clean this structure is manually.
The cleaning workers, after fastening with safety belts, will climb onto the roof structure and attach the safety belts at the apex of the structure to carry out the cleaning task.
This method of cleaning has been carried out only once due to high level of danger involved in the use of this method.
Now, this dome-shaped roof is no longer maintained.

Figure 1 : Robinson Point

For Robinson Point, it is similar to the Wheelock place in that there is a gap between the pointed roof and the external façade.
It stores the access system permanently in this gap as there is no storage space on the pointed roof.
The system employed is the trolley unit running on a guide rail i.e. trackless system.

Figure 2 : Illustration of accessibility problem at Robinson Point

As illustrated in Figure 2, the spreader bar at the end of the jib is more than 1.5m high and when it extends out, it will hit the wall.
The management has to demolish part of the external wall and build a small door.
When the gondola is needed for cleaning, the door will open for the spreader bar to extend out.