They work effectively in temperatures down to 25 f.
Rock salt on metal roof.
Rock salt is not effective on surfaces below 0 fahrenheit.
The tablets help prevent roof damage by melting through ice dams and allowing water to drain safely.
As a result it can cause damage to vulnerable parts of your roof including nail heads and aluminum flashing.
It also does not work well below 20 degrees fahrenheit.
Ice melt works in below zero temperatures.
Why you shouldn t use rock salt on your roof.
If you expose the inside of gutters to salt throughout the winter the salt will eat through the finish on the inside and begin corroding the metal.
Rock salt can also leave permanent stains on your roof and walls.
While safely on the ground toss a roofmelt tablet onto the roof.
The dangers of rock salt on roof shingles rock salt s ability to damage driveways and other outdoor pavements is relatively well known but there is another place where rock salt can do damage to your home on the roof top.
Unless you rinse gutters and apply a new protective coating after each freeze thaw cycle salting will ultimately damage your gutters.
Rock salt is corrosive to roads concrete and metal your car.
An excessive build up of some types of ice melt may become toxic to the environment though newer safer brands are now on the market.
Rock salt is corrosive in nature.
For these reasons rock salt is not a good choice when it comes to getting rid of ice dams.
Melted water with rock salt mixed can drip off the roof edge and onto stone or brick masonry.
Again for the most part you don t want to throw any type of ice melt product on your roof.
Use ice melt only when there s no alternative.
However rock salt is a form of sodium chloride which corrodes metal including the metal nails holding your shingles in place.
It can damage masonry.
Salt is damaging to plants and very few varieties are tolerant enough to withstand the dangerous levels that can occur when you use rock salt on your roof.
Use roof melt tablets to reduce snow and ice buildup that occurs on your roof typically on the eaves and in gutters.
Three to four times more expensive than rock salt according to this site.
The roofmelt ice melt is designed to eliminate the need to climb onto roofs while melt snow.