Salting sidewalks: is it worth it?
The short answer: not always!
Realtor.com asked me recently whether pre-salting a driveway before a storm is a good call. They had questions about environmentally friendly options, but in all cases, the reality is that New England weather is variable, and so are the conditions that dictate what snow removal method will make the most sense.
Kate Ziegler, a RealtorⓇ with Arborview Realty in Boston and with Coldwell Banker Lifestyles in New London, New Hampshire, says that salt can be very helpful—in certain conditions. “Salt works at melting icy surfaces when combined with warmer ground temperatures, sunshine, or friction from traffic,” she explains. “But if it’s very cold and heavy snow is forecasted, salt will do very little beyond making its way into your snowbanks when you eventually clear the driveway.”
In other words, the colder the temperature, the less effective salting your driveway will be. When you get down to temperatures of around 15 degrees or lower, rock salt is basically useless.
Salt works at melting icy surfaces when combined with warmer ground temperatures, or sunshine, or friction from traffic—but if it's very cold and heavy snow is forecasted, salt will do very little beyond making its way into your snowbanks when you eventually clear the driveway. Remember the "bridge freezes before road" warning signs posted on highways everywhere: when the ground is colder, salt is less effective. Salt beneath snow won't prevent snow from piling up, if that's what's in the forecast; salt spread before an overnight ice storm might help things melt faster if the conditions are right.
Conditions perfect for salting? Yesterday’s snow-rain-snow in Boston. As temperatures warmed, the morning’s soft powder started to melt; when temps fell after dark, sidewalks that had been cleared but not salted ended up with a slick of black ice from the continuing drizzle. (And anything not shoveled at all yesterday is a frozen former-slush block this morning.) Today’s sunshine will help icy drives and walks to melt more quickly under the influence of salt. Don’t fear salt today!
Keep in mind that beyond any environmental concerns you may have with salting, the salt is also corrosive to brick, concrete, asphalt, and especially to metal. I can't tell you the number of times I've seen corroded joist hangers flagged in home inspections where the owner was clearly salting a path on their exterior wood stairs or deck. Joist hangers are easy to swap out, but salting will dramatically shorten their lifespan. Be cautious about salting heavily on and around your home or garage, in addition to any green space.
Depending on where you live and the specific conditions, sand can be a great option for adding traction. This works both in warming in sunlight to help melt surface ice, as well as just adding some traction over the surface. If you happen to have a wood-burning stove or fireplace as part of your heating plan, wood ash can also be effective both at melting and adding traction. We use wood ash to deice our unpaved driveway in NH: shoveling a dirt driveway beyond what a plow can clear is really a fool's errand, so the traction and melt help is what we really need in that case. But, because we're in the woods and so close to a waterway, commercial salts aren’t a good option.
Be warned that one of the key mineral components of wood ash is potassium salts—which can have some of the same cons as commercial deicing salts (corrosion, soil balance change, etc.). Both sand and ash are messy when wet, so be prepared to leave boots at the door.
If you need them, find more recommendations from Realtor.com, and stay warm and dry!