Ice Dam Myth: Gutters Cause Ice Dams

Some myths are painful and costly.  The notion that gutters cause ice dams to form on your roof is one of them.  This myth has lingered like a bad smell, and has resulted in many puzzled, frustrated homeowners.

Two types of people will tell you that gutters cause ice dams: people who don’t know the science behind ice dams, and people who want to sell you a gutter system that supposedly prevents ice dams from forming.

In order to separate fact from fiction and to make the right decisions for your home, here’s what you need to know:

You probably remember that ice dams are caused by your roof heating up to a temperature greater than 32 degrees.  That’s the underlying problem.  Obviously, gutters have nothing to do with this.

However, a house with gutters can sometimes be prone to larger, thicker ice dams, when compared to a similar house that doesn’t have gutters.  Both houses will have ice dams, but a house with gutters will have a bit more ice along the edge of its roof.

[singlepic id=97 w=360 h=270 float=left]Why?  Simply because gutters stick off of your roof, which essentially means that your roof has more overhang (than if you didn’t have gutters).  Gutters just allow the ice to crawl a bit further past the edge of your roof overhang; in essence, they extend the area of your overhang.

The more feet of overhang on your roof, the greater the potential for big ice dams forming.  This is because the overhangs (obviously) are the only parts of your roof that don’t have any attic space underneath them.  They’re not being heated from underneath by your attic.  That means the overhangs are cold.  If you have literally tons of snow gradually melting and flowing down to a vast cold area, you can bet that the big cold area (the overhang) will refreeze all of that water…into ice.  This equates to a larger, thicker ice dam than you would have had without gutters.

But regardless, you would have had ice dams anyway, so don’t go tearing the gutters off your house in an effort to prevent ice dams this winter.

Gutters do not cause ice dams.  If people try to tell you otherwise, either politely correct them, or slam the door in their face and let them use the money they make from their revolutionary “no-ice-dam” gutter system to have a surgeon un-flatten their nose.