Snow and ice are not typical guests in the Carolinas and southeast, but occasionally they come to visit and create stress for property managers as they try to minimize impact on the tenants and guests while mitigating potential liability through reasonable efforts to resolve snow and ice conditions.
But what type of snow and ice melt works best? And what products will create the least amount of “collateral damage” to the exterior pavers and landscaping as well as the interior lobby stone as people track the chemicals inside?
According to a nationwide poll of facility managers, a quick acting product was the top priority, followed by potential harm to concrete and pavers, working at low temperatures, non-tracking, and finally harm to landscaping.
The easy, go-to product is rock salt, or sodium chloride (NaCl). Salt reduces the freezing point of water through an endothermic (heat absorbing) reaction as the sodium and chloride take up space in the water molecules that makes forming ice crystals more difficult. While effective until about 20 degrees Fahrenheit, rock salt has several downsides.
In addition to leaving salt on top of the pavers, concrete or other surface that can be transferred to and erode metal and other materials (think rusted vehicles in the northeast), the salt also works its way inside the pavers and below the surface. As the salt-infused water works its way through the stone, the salt is left behind once the water evaporates. The resulting salt residue, which can take the form of flaking or scaling, is known as salt fretting or subflorescence and can severely damage masonry and look terrible, particularly where outdoor masonry meets the building.
Fortunately, several alternatives exist to rock salt that create less damaging by products and harm to the surrounding environment.
A preferred alternative to rock salt is calcium chloride (CaCl2). While more expensive that rock salt, calcium chloride can melt 2-3 times the amount of snow and ice as rock salt and is effective down to minus 25 degrees Fahrenheit. It is also the least damaging to concrete and can act like a shield against future freeze and thaw cycles. Furthermore, calcium chloride has an exothermic (heat producing) reaction to moisture and leaves a clear brine solution that is less noticeable when tracked indoors (more on that in a moment).
Potassium chloride (KCl) is another alternative because it is less irritating to the skin and less harmful to surrounding landscaping. However, potassium chloride is slower to melt snow and ice than calcium chloride and leaves a white residue.
Magnesium chloride is also an alternative, but is known to be harmful to concrete and can clog spray nozzles as the temperature drops. It also releases more chloride into the environment than calcium chloride and has three times the toxicity. In a side by side comparison, magnesium chloride melted 25-40 percent less ice than calcium chloride.
For its superior properties and pound for pound effectiveness, calcium chloride is a top choice for snow and ice melt. It is available online and through common brick and mortal retailers and distributors, and is available in pellet form or liquid.
In conjunction with calcium chloride application, we recommend walk off mats on lobby floors to mitigate the risk of slip and falls as well as tracking of snow, ice, and ice melt such as the clear brine solution of calcium chloride. A minimum of 4 feet of mat should be used, and longer mats of up to 10 feet in length are preferred for high traffic areas. The conditions of the mats should be monitored more frequently as snow and ice conditions persist.
For ice melt that does make it onto stone lobby floors, we recommend cleaning the stone periodically after ice melt has been distributed and until the ice melt is gone to reduce slip and fall risk and damage to the stone. A neutral cleaner should be sufficient to remove any residue.
While snow and ice create additional challenges for property and facility managers, taking care to use the right products can make a big difference in effectiveness, risk mitigation, and environmental impact.