This is Your Roof. This is Your Roof on Salt.
“Just say no” to salting your roof. Unlike other substances, salt won’t impair your cognitive functions, but people might conclude otherwise if they see what you’ve done to your roof and property:
- Discolored shingles
- Dead shrubbery
- Dead grass
- Discolored driveway, sidewalks, or front stoop
- Corroded gutters and downspouts
- Rust and pits on your flashing, which may eventually cause roof leaks
- Rusted roofing nails and flashing which may lead to rust streaks on your roof
- Saltwater leaking into your home as a result of said leaks
- Tummy aches (or worse) for any animal or person who likes to eat snow
You’ve seen what road salt does to the undercarriage of cars in the winter – how it can rust and destroy a car. That’s bad enough. Now imagine doing that to something you took out a mortgage to pay for, and have to look at every day.
But what about if you must use salt, for whatever reason?
If you’ve got a roof leak in the winter, probably so do most people in town. So maybe you’ve called every reputable ice dam removal professional around, and they’re booked or didn’t even pick up. If water is pouring down your walls and pieces of sheetrock have plopped onto your table, you might conclude you’ve “just got to do something,” and all you’ve got is salt.
If you must use salt, at least choose the right type of salt.
There are five commonly used types of ice melt (a.k.a. salt). Although there are others (e.g. urea, ammonium sulfate, glycols, formates, etc.), they are not easily obtainable, nor are they widely used.
The Big Five include:
- sodium chloride
- magnesium chloride
- calcium chloride
- potassium chloride
Each of these ice melt products lowers the melting point of ice to a different temperature point.
You can read here more about all those types of ice melt. In our experience, magnesium chloride is the safest and all-around best “easy to find” ice melt you can use in an absolute emergency. Although magnesium chloride still has risks associated it, in my opinion it’s the lesser of all evils. Note: Glycol-based products are also a good alternative, but they’re expensive and can be extremely difficult to find.
Warning: the salt in your garage is probably not magnesium chloride or glycol-based.
Most ice melt products rely on sodium chloride. That’s the one that can leave stains all over your house, rusts the underside of your car, and kills your grass.
Why, then, do people still use sodium chloride?
Because it’s cheap! And…it’s not even that effective when compared to other ice melt products out there. For example, sodium chloride only reduces the melting point of ice to about 20°F, while most of the other ice melt products on the market (also much safer than sodium chloride) reduce the melting point of ice to somewhere between 0°F and -25°F.
Another draw of magnesium chloride is that it’s reasonably safe for your pets and more environmentally friendly. Also, it’s the least likely to cause all the damage listed above. If you use it, make sure it’s pure magnesium chloride; many ice melt products contain a mix of other types of salt. Safe Step Extreme seems to be one exception, in that contains mostly magnesium chloride with just a bit of calcium to speed things along. Road Runner is another brand that mostly includes magnesium chloride. My advice is to read the label, because most ice melt companies continually change their “recipes” for better results or higher profits.
What about Glycols?
Although not one of “The big five”, glycols are worth talking about because they tend to be pretty safe for the environment, and they’re also quite effective at melting ice. This website mentions that you’ll also get “fewer” salt stains with glycols than you would with, say, sodium chloride. However, that is not a guarantee against discoloration.
There are two main types of glycol used in ice melt products: propylene glycol, and ethylene glycol. Propylene glycol is generally considered the safer of the two.
The trade-off with glycols is that, although they work pretty quickly, they’re expensive and can be difficult to find. They often work more quickly than even magnesium chloride does. If you’re in dire straits, that might matter to you. You might think “it’s environmentally friendly enough, the chances of damage to my roof and surrounding surfaces are low, and I need this ice dam melted now.” That’s your choice. Just know that there’s always some amount of risk when using any type of ice melt, even a glycol-based product.
As I said before, the drawback of glycols is they tend to be much more expensive and harder to find than magnesium chloride. So if you’re trying to save a buck, and you’re trying to avoid damage, you might still want to pick the magnesium chloride. The difference in the amount of time either takes to begin melting your ice should be negligible enough that you won’t want to shell out the extra cash for the product, or for the potential damage it may cause. (How much more expensive are glycols? Three to four times more expensive than rock salt, according to this site).
Use ice melt only when there’s NO alternative!
Again, for the most part you don’t want to throw any type of ice melt product on your roof. But if you’ve let your ice dam fester for so long that you can’t even get a credible ice dam company to help you because they’re booked solid, salt may help you emerge from your DIY ice dam removal adventure as unscathed as possible. (Emphasis on the “as possible” part.)