Should You Use Salt or Sand on an Icy Driveway?
Updated for 2019: This post has been updated with new information.
Taking a spill on your icy driveway is bad enough when youre carrying your car keys. So imagine wiping out while carrying a dresser full of clothes. Scary scenario, for us and for our movers. (And one reason people prefer to move in summer.)
If the forecast for your move date calls for moisture and freezing temps, you might be thinking: Should I cover my front walk and driveway with salt or sand? Sand is used to cover up the snow, salt will melt it.
If you have the option, sand is always better.
Why? Lets break down first how to best apply both of these, which will explain the pros and cons of both.
First of all, shovel the area youre going to walk
The best defense is a good offense. If it snows the night before your move, it almost goes without saying that the first thing youll want to do is grab a shovel and get to work clearing the area.
If you live where temperatures can remain below freezing for days on end (if not weekshello, Minnesota!), then youll understand the importance of shoveling your driveway before all that snow gets packed down and turns to ice.
Now lets decide whether to melt that ice or cover it up.
Sand or Ice?
If Mother Nature insists on coating the driveway with ice, we have two choices.
We can either melt it or cover it up.
The answer depends on how cold it is, as well as how much you care if it gets into the environment. In either case, the biggest priority is traction.
The case for sand
Covering up ice in our way can be quick and pretty easy. All we need is a bag or two of sand.
Sand is less toxic, much cheaper, and works immediately.
But you might have to keep reapplying it. Keep in mind these few things:
- Since sand provides traction, once it gets ground into the snow or ice it becomes less effective. As many times as you or your movers will be walking back and forth on it, youll likely have to put more down once or twice during the move.
- In extremely cold temperatures,sand can freeze in hazardous clumps. Some suggest adding salt to the sand to help prevent this from happening, but if its cold enough, that salt wont help either (more on that in a minute).
- Sand comes in several varieties. The stuff explicitly meant for icy roads is better than sandbox sand, which in turn is better than something like masons sand. In other words, the grittier, the better.
- After the fact, sand can collect in drainage systems and the soil, eventually clogging up lakes, streams, pipes and sewers. That means its also getting into our drinking water. Clean up what you can or give the neighbors kid a few more bucks to make sure its cleaned.
The case for salt
Instead of covering your packed snow and ice with sand, you can try melting it with salt. Because its specifically designed for this purpose, it can definitely be an attractive option.
But if you dont apply salt several hours or a day or so ahead of when you need to safely walk on the area, salt is largely pointless, as it needs time to begin working.
Running out and buying the biggest, cheapest bag you can find might be your first instinct, but as with sand, there are a few things to consider.
- Driveway salt, sometimes called rock salt, doesnt melt ice like, say, a hot rock or a flamethrower would. Instead, when mixed with water, it forms a liquid brine (a fancy name for salt water) which has a lower freezing point than pure water. This brine then acts to lower the freezing point of the water it comes in contact with, effectively melting italthough only down to a certain degree. (Brine that is 20% salt will still freeze below 0F.)
- Throwing some salt down on your icy driveway will get you nowhere if its too cold for the salt to actually mix with the ice! The salt needs to draw moisture from the air to create a brine which will act on the ice it touches, which will melt and further the reaction. Alternatively, there needs to be some heat, from the sun or from friction, to initiate the melting process. In other words, dont wait until your movers are pulling up to your house before you start throwing that salt around.
Other concerns about salt
The cheapest and most plentiful salt youll find is basically table salt, or sodium chloride (NaCl). That may sound perfectly safe, but do be aware:
- That salt may contain small amounts of cyanide, which isnt exactly good for any curious pets or animals.
- Using salt can cause metal to rust and can damage blacktop, cement, flagstone, brick, wood and pretty much anything else your driveway is (or has). If youre interested, this damage is not merely from the salt, but from the increase in freeze/thaw cycles that come with the brines lower freezing point, which can begin to break down the integrity of the surface with which it is in contact.
- Got a cool yard? Salt can damage plants by inhibiting their ability to absorb water and nutrients. Salt also leaches heavy metals into the water supply.
- Got pets? If salt gets lodged in your pets paws, it can cause a nasty burning.
There are also salt and sand alternatives!
Alternatives to salt would more accurately be called variations of salt and have a spectrum of merits. While you can probably find any of these at a store, which one to pick is most dependant on exactly how cold it is where you are.
- Calcium chloride (CaCl): Covers a wider area than rock salt with a lower freezing point (around minus 25F). It also works more quickly because it gives off heat as it dissolves. Like rock salt, calcium chloride is corrosive to metal and can leave a slimy residue. It also encourages algae growth which clogs waterways.
- Magnesium chloride: Its similar to calcium chloride, albeit somewhat less corrosive, and will begin to absorb moisture from the air at 32% humidity, speeding up the melting process.
- Potassium chloride (KCl):Despite its use for executions by lethal injection, is safer for pets and plants than calcium chloride. With a freezing point of around 12F, it is also less effective.
- Nitrogen-based urea products:This is similar to fertilizers in that they are expensive, ineffective under 20F and, like other salts, will eventually get into the water supply, lakes and streams.
- Calcium Magnesium Acetate (CMA):Can prevent ice down to around minus 27F and is much more environmentally friendly than the abovementioned salts at a much higher price.
Are there more eco-friendly alternatives?
With all the pros and cons of these salts and chemicals, you may be wondering, Is there an eco-friendly way to de-ice my driveway?
Yes. Maybe. It depends on your definition of eco-friendly and your motivation to be so.
But what everyone seems to agree on including us is that theres no better way to keep your driveway and your front walk clear of ice than grabbing that shovel and getting to work.
Or maybe get the neighbors kid to do it.
- Salt and sand the day before your move, clearing away any chunks or other bits to help keep it all from refreezing overnight.
- Applying salt the morning of your move? The heat from all the foot traffic will help the melting process, but in the meantime,scattering some sand on top wouldnt hurt.
- Get an idea of how much square footage youll need to cover before you run out to grab that salt or sand. If a sales assistant isnt there to help, you might find how much you need right on the bag.
And remember, get rid of whatever snow and ice you can along the way. Your movers will love you for it.