Two small disclaimers are necessary in the beginning itself:
- all the opinions voiced in this Post are my own and not that of any organisation that I worked with or am currently working with.
- Some of the descriptions of buildings and problems faced therein are mentioned in this post, without actually naming them or giving out their locations. If the readers find some matching buildings in their own imagination or experience, it is their own imagination.
Glazed facades / domes / atrium roofs
Glass has been a great building material for quite some time. The technology improvement in making plate glasses have brought in a large variety of glass in various hues, colours, sizes and shapes available to the architects and building engineers. What this has brought about is large glass facades, walls, doors, etc at times measuring a few acres of surface area in a building.
The artistic domes atop buildings and atrium roofs add style and glamour to buildings.
Glass has become an integral part of every building in view of meeting the “Day light harvesting” requirements, grand facades, reducing stored heat or cold as the case may be and other architectural interests.
When compared to painted or other types of external wall coverings, glass offers a longer time line between maintenance cleaning and other work on them. The smooth glass surface is less likely to retain debris, dust and moisture compared to rougher painted surfaces and porous natural stone coverings. The use of a combination of glass and aluminium cladding for facades has caught on like wild-fire.
Not withstanding the above facts, glazed exteriors also require periodic maintenance – this is an inescapable fact.
Architects, building engineers and building / facility owners also need to be aware of the glazed area maintenance requirement at the building design stage itself. If the maintenance related provisions are made at the design stage, the implementation of periodic maintenance becomes easier and fool-proof. I am going to cover the challenges in glazed area maintenance in a series of case studies.
Case 1. Small factory building with glazed facade
In this building the glazed area was basically for show purpose. The architects had not provided any means to do glass cleaning. The height was not much, but more than what was reachable even with the longest telescopic glass cleaning equipment. There were no accessible perches in between, to provide access. There were no anchor points provided on the flat terrace, to allow people to access from the top. The dusty external environment made the facade dirty very frequently. As the Facilities Management agency for this building, we suggested procurement of a scissor / boom lift for the facade cleaning purpose. the same equipment could be used for other purposes such as high mast light fitting maintenance, accessing the steam / chilled water / DM water pipes running on raised structures etc. It was a worthwhile investment wisely made by them.
Safety Factors in Using a Scissor / Boom Lift
Only a trained and authorised person should be allowed to drive and operate the scissor / boom lift. The driver may not necessarily go up with the lift while the cleaning person is on task. The driver needs to be around to assist in changing the height of the boom, moving it to the sides etc. These operations / controls of the boom bucket should be with the driver alone.
The people undertaking the cleaning should wear all essential PPE such as safety helmet, nose mask and eye protection (in case of flying dirt and debris) and a full body safety harness that is anchored to the boom bucket anchoring points.
Scissor / Boom lifts should be parked in more or less level ground, before the people are lifted up. Positive additional support using hydraulic jacks should also be applied.
Case 2. Very well-known education institution with a large academic centre with a deep atrium and tall central structure
The architects had chosen natural stone for covering the external walls. The stone colour would not show much of the dirt that settled on its rough surface. The central tower was totally air-conditioned, hence had sealed windows. There was no way to access the window panes from the outside since it was too tall to reach from the atrium. Atrium was accessible only through staircases, thus ruling out a boom lift or other types of vehicles entering there and being used for access. Yes, we could have lowered a vehicle in using a heavy-duty crane, but the vehicle would have been constrained to remain within that area and would have been underutilised.
There were no anchor points provided on the terrace. The terrace layout and structure were not amenable to lay a trolley for a davit and cradle arrangement to move around the periphery. The management was not very keen on making a big capital expenditure for the facade cleaning equipment also, since it was not budgeted for in the initial plan.
Yes, spider man technique using improvised anchor points could have been used.
I am not aware as to how they finally managed, since I left the facility for other new projects and at a later date my company stopped working in that facility too.
Case 3. A Tech Giant with a large office space completely covered with glass all around
In this case every thing was provided for. A clean rectangular foot print for the highrise building allowed clean runways for the davit to run on the terrace and enough space to lower the cradle at all positions. Good quality, known brand of cradle mechanism was installed and operated as well.
Safety Factors in Using Cradle Mechanism
The people using the cradle mechanism are to be trained, tested and authorised for using the same. Periodic refresher training and testing are also required. “Train the trainer” route also could be taken on the long run to train a couple of internal trainers, thus reducing the recurring training cost.
All essential PPE should be issued and used by the people assigned to the cradle work.
Work permit should be issued after ascertaining the safety aspects and hazards analysis. The wind speed should be a maximum of moderate levels only – otherwise too much of swinging of the cradle could lead to accidents, banging onto the building facade, damage to the facade including glass etc.
Review of load test certificates, ropes and other load bearing members of the cradle arrangement should be done before attempting to operate. All periodic statutory tests and certification are to be current before starting operations.
The building owner and users should be briefed about the facade cleaning work plan.
Necessary barricades for risky areas, security personnel posted at tactical positions to guide other users and full supervision of the work are essential to ensure total safety.
Case 4. An automobile manufacturing plant with a network of long interconnected production bays.
The designer had provided for “Northlight” glazed areas in each bay. The roofs were slanting type, with sheer falls at the northlight area. All the glass panes were sealed to their frames to avoid ingress of water during rain. The glazed areas were not accessible from the ground due to height and other structures blocking the path for boom lifts. The only access was from the roof. Climbing on the roof itself was a hazardous exercise, due to the complex structures and the slope.
Just to help in visualising the problem, a representative drawing of the bare structure is given here.
The cleaning from inside was comparatively easier since the cleaning crew could climb on the internal structure and reach the glazed area.
Much thought was given and ideas were discussed before reaching the ultimate decision on how to safely work on this job. A steel rope was anchored to both ends of each bay and tightened as far as possible. These ropes were further anchored to some points on the lower side of the sloping roof, so as to keep the rope as taut as possible. The work platform was hung on to the rope with a pulley arrangement to lower and hoist. People working from the platform were anchored to the rope using extension bits and the full body harnesses.
Getting the “Work permit” each day was a mammoth task since the Company management wanted a zero accident record. We managed the same without any mishaps barring minor abrasions to a couple of people.
Imagine the team that does facade cleaning on the World’s tallest tower “Burj Dubai” and other such buildings!
The idea behind this blog entry is to get the regular readers thinking on the right lines from the building design stage till the regular maintenance.
Comments and suggestions are welcome. Thanks in advance!