By: Adam McManus

During new construction and façade restoration projects with multiple wall systems, the protection of glass surfaces is often neglected. Wherever brick and mortar facades are integral, it’s common for mortar droppings to attach to the glass and frames of window systems. Once mortar dries, the proper removal process is key in order to avoid scratching the glass or frames.

Typically, high rise buildings with glass curtain wall systems are regularly cleaned to maintain the clarity of the glass and avoid a heavy build-up of atmospheric particulates and stains. There are safety hazards involved with a window cleaner’s job, including: equipment failure, high winds, etc. In November 2014, a window cleaner was stuck on a tipped suspended scaffold at the newer World Trade Center 1 building. In the past decade, there has been an uptick in the use of robotic cleaning devices for large curtain wall systems. This may help address the limits of accessibility and provide an alternate semi-automated solution to reduce the elevated safety risks associated with the industry.

However, window systems on mid-to-high rise buildings may not be cleaned as often. Many of these buildings have no cleaning and maintenance programs in effect, nor davits on the rooftops for suspended scaffold systems to reach the window systems. The exteriors of double hung windows can sometimes be accessed through interior spaces. Fixed window systems on multi-story windows may be accessed from the ground with extension poles that can reach 50’ or more.

Heavy particulates on glass are much more difficult to clean if not performed on a frequent basis. Metallic stains and corrosion encrusted on the glass can be particularly difficult to remove.  Surfactants such as mild detergents are often required to break down the scum buildup. A very fine steel wool brush, rated super fine 000, may also provide abrasion for mechanical removal.During new construction and restoration projects, a specification section should include glass and window system protection to avoid unnecessary damage to new and existing units. It’s much more costly to replace units and entire systems than it is to apply protective film and enclosures as required.

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