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"Buildings are architectural statements with sophisticated and intricate envelopes. Architects around the world explore the limits of façade design creating buildings which attract tenants and capture the interest of the surrounding community. Additionally, a building’s façade will provide weatherproofing, insulation and a means of allowing natural lighting to enter the premises. It also increasingly forms a significant part of a building’s overall aesthetics. Façade cleaning and maintenance has therefore evolved significantly, as bespoke systems must accommodate a tight operating space, whilst meeting the growing demand for replacing façade panels and plant components during the service life of the development. Façade Access consultancy can be provided from the very early concept stages, through project management, to equipment testing and beyond, to seek the ideal solution to building maintenance which is code compliance whilst being cost effective as far as reasonably feasible."
Associate Director, TÜV SÜD Dunbar Boardman
Wednesday, January 13, 2021
Why should a building’s elevation be cleaned? The issue of aesthetics first comes to mind. After all, a clean building presents a more hospitable front - and therefore a more attractive real estate prospect - to the public. As the quest grows to develop more individual and impressive buildings, increasing emphasis is being placed on the building façade with respect to the detail, quality and proportion of overall budget attributable to the building façade. Like all building elements, façades can be subject to soiling and structural deterioration, often accelerated by exposure to man-made pollutants. To ensure that façades remain aesthetically pleasing, effective in terms of functionality and structurally sound, a well-planned, economical and effective cleaning and maintenance regime is a prime concern in the overall design concept.
Of course, not all building façades warrant the same amount of care and attention. A building’s location, function, and geographic and atmospheric conditions all play roles in determining the level of cleaning effort necessary to achieve the desired appearance.
The Building Research Establishment notes that all façades require a degree of maintenance if they are to fulfil their intended working purpose and that, in the event of failure, tenants, owners or occupiers could have “a legal liability for personal injury caused to staff, all visitors to your building, and members of the public in the vicinity”.
Damage or deterioration to façade elements can result in water penetration, falling debris and, in extreme cases, façade failure — all of which have the potential to cause harm. Such issues often originate from lack of regular routine maintenance and proper care of the building façade.
Practical, economical and effective maintenance should therefore be a key consideration in the overall design concept. As the building maintenance strategy is in place throughout the lifespan of a building, the development process for an effective façade access solution should be long-term - and getting it right is critical. However, as façade access is a specialist field, there is limited expertise within the construction industry worldwide.
Design Implementation of Façade Access Systems (FAS)
Façade maintenance ranges from regular cleaning of the glazing to the replacement of failed panels to conditional survey by a specialist, all of which should be undertaken by suitably qualified and experienced persons, as “to the experienced eye, there may be indications of potential failure, months or even years before the failure actually occurs”. Operatives can be exposed to the hazard of falling from a great height and these risks may occur when:
Access options can simply be from the bottom-up or from the top-down. For low rise developments (preferably up to 40m), mobile aerial work platforms can be employed. In this case, the surrounding landscape must be taken into account to ensure that enough ground space has been allowed for the working machines.
The demand for more space for living and working is apparent everywhere which puts pressure on increasing usable space coupled with requirement for roof-based services (PVs, landscape, etc.) particularly for high-quality offices. The fact that upper level space has becomes the fifth elevation and includes external terraces and communal spaces. Panoramic views are at a premium creates a conundrum when working with older buildings originally designed with attics/ mansards, degressive proportions and constrained ceiling heights. Negotiation with planning, technical and urban issues result in demand for compact façade access to blend within narrow zones. This meant that space for façade access solutions were further constrained. To leave the perimeters free and unobstructed, a single BMU with a longer reach was therefore located in the centre of the roof.
Regardless of the BMU’s position on the roof, coverage can be a challenging on buildings with complex façades. Twisting façades produce problems of their own and sky bridges create dead areas. When complicated façades also incorporate glass replacement, the challenges are magnified.
An option that is frequently considered is to use the BMU to lift glazing or various other sections of the façade. At this point, it is important to note that the total suspended load on a glass lifting winch is limited to 1 tonne as per BS EN 1808.
Unless it is subjected to an external force, once the glass is installed it will usually last beyond the lifespan of the building. After the practical completion of a building, individual panes of glass failure is extremely rare. It is more likely that glass panels are replaced because of warranty failure.
In other instances, glazing panels are replaced from the inside either by delivering the panel via goods lift or externally using the BMU subject to façade design. Clear operating zones are therefore essential for transporting the glazing manipulator (and panel) within the building to the replacement location.
The effects imposed upon the building structure of ‘in-service’ and ‘fall arrest’ loads from the operation and storage of FAE are significant and should be coordinated with the structural engineers from the outset. Loading paths through the structure should be taken into consideration when evaluating the reactions of the façade access systems, to include all its operational and stored positions when fully loaded.
The equipment connections on the structure should be welded, bolted, or cast in place. The attachment method should be defined during the earliest possible design stages so that the correct provision can be made for the fixings to be integrated within the roof finish, and to allow periodic inspections.
Undeniably important factors, such as safety and stability, are determined by local regulatory codes and industry standards, and they should be incorporated in the design calculations of the FAE and building structure.
The TÜV SÜD Approach
The very wide and diverse requirements for building access systems highlights the importance of a totally impartial, independent consultancy to identify and resolve the specific requirements. "Off-the-shelf" equipment may not be appropriate, and the designer now requires a comprehensive knowledge of the real capability of companies in the field and the ingenuity to develop appropriate cost-effective schemes. Building-specific solution has to be reached often with a degree of technical innovation and an open mind. This process can no longer be constrained by advice from suppliers, which is restricted by their own specific knowledge, capabilities and equipment.
Our design planning team brings extensive experience and innovation to planning permanent access equipment for exterior and interior maintenance—helping to ensure the highest degree of equipment effectiveness that is compatible with the building’s design, the owners’ investment and cleaning time analysis.
About the Author:
Mohamed Merchant is an Associate Director at TÜV SÜD Dunbar Boardman, Europe’s leading elevator, escalator and access consultancy. He has 20 years’ experience in mechanical engineering, including 19 years in the façade access industry. During this time, he has designed and delivered façade access strategies and systems for major developments within the UK, Europe and the Middle East, including high-rise residential and commercial office developments, retail centres, refurbishment projects, hotels, hospitals and historic buildings.
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