As we are in the heart of winter in New York City and with recent ice fall incidents, it is a good time to consider the potential dangers of ice accumulating and falling from tall buildings. This winter has already seen some of the coldest temperatures on record combined with precipitation quickly followed by substantial rises in temperature.  This creates the perfect environment for the formation of ice on façades and the subsequent quick melt that can result in significant sized pieces of ice falling onto pedestrian areas below. 

What can an owner or manager do to mitigate the possibility of injury to the public?

Before answering this question, there are a few things that should be noted that may affect ice accumulating and falling:

• Advances in the energy efficiency of buildings has reduced their exterior surface temperature.

• Incorporation of architectural features such as solar shades & rain screens.

• The ability to build taller and more irregular shaped structures. 

• Growing use of materials such as glass and metal on façades.

All of the above, combined with current extreme weather conditions being experienced, the potential for and frequency of ice falling from city buildings will only continue to increase. 

Owners and managers of buildings susceptible to ice build-up should remain vigilant during the winter months and diligently monitor weather forecasts in order to know when the potential for precipitation combined with freezing temperatures is predicted. Façades should be visually inspected during these weather conditions and it should be documented when and where ice formation is observed and most importantly, when incidents of falling ice occur. Logs should be maintained at the building for reference. By documenting the exact weather conditions (temperature, precipitation levels, wind speed & direction, etc.) when these occur, owners will be able to better predict and prepare for future occurrences ahead of time.

Based on the information collected, a maintenance plan should be implemented wherever possible to remove built-up ice from façades prior to the ice beginning to melt. Building engineers should regularly remove ice from any reachable projecting elements, horizontal sills and ledges and other areas known to collect snow and ice. Non-permanent projecting items such as window mounted air-conditioning units should be removed in winter months to eliminate them as potential collection points. This overall approach is not feasible with newer curtainwall construction that does not have operable windows but should be implemented at buildings with ice issues that have operable windows. Ice should be knocked off any reachable areas in a controlled manner. Areas below should be made safe by temporarily blocking pedestrian access to the walkways below while the removals are in progress. All ice that is removed from the façades should be cleared from the walkways prior to re-opening the area to pedestrians. This maintenance method can only be implemented at buildings with operable windows and, even at those, the accessible areas to remove ice from will likely be limited.

Outside of major façade modifications, protection of the pedestrian walkways is the most effective approach to minimizing the potential for injury due to falling ice. Temporary protection can consist simply of blocking off the areas below locations of falling ice with caution tape and having building staff direct pedestrians to walk under a covered area (if available) or directing them to walk on the sidewalk across the street.  

So, what is a better solution? A more feasible temporary alternative for buildings suffering from excessive amounts of icefall is to install a sidewalk bridge that covers the full width of the walking area, by adding catchalls to the installation, portions of the street can be protected as well. The bridge would be installed at the onset of winter weather and removed as spring arrives. This too can be costly to install, maintain and remove on a yearly basis. Additionally, this strategy requires permitting/filing with the Department of Buildings (DOB) but it can potentially prevent serious injuries to the public.

A permanent solution to address high-trafficked pedestrian walkways prone to significant amounts of falling ice is the installation of an impact-resistant canopy. The installation does not have to cover the entire pedestrian way but should cover the most highly trafficked areas and protect sufficient width of the walkable area to accommodate the regular pedestrian flow. During times of potential icefall, pedestrians should be directed away from the unprotected areas to the area under the canopy.

As the energy efficiency of buildings continues to develop and different materials are used, more attention will have to be paid to addressing and preventing ice and snow build-up on building façades. Strategies will need be developed more thoroughly and incorporated into the original designs of future buildings. However, for existing buildings, cost-effective and practical means must be explored to provide for the safety of the public and to minimize owner liability related to injuries and damage caused by falling ice.

Matthew Cronin, RA, is executive VP, NYC of The Falcon Group, New York, N.Y.