Icicles on the Roof

Posted by Ben Thompson on 12.9.09

Date: 12/5/09


Subject: Icicles

Good Morning!

I am unable to call in during the show this morning, but I will be listening.  If you have time to answer this question, I would be very thankful.  You probably have addressed this concern many times, but here is my situation.  I have inherited and am living in my parents' single-story ranch-style home which was built in the mid '50s.  I am still learning about the structure including the things that need to be updated and improved.  After yesterday's snowfall, many icicles formed around the roof of the house especially at the front which faces south.  I don't ever remember seeing so many large icicles this early in previous winters.  I typically rake the snow off the edge of the roof after a heavy snowfall but was unable to do so yesterday.   For my home heating, I have natural gas and an automatic thermostat which is set at 62 degrees for the day and night hours except at 68 degrees for two hours in the morning and for several hours in the evening.  Could these icicles do damage to the roof?  (There are seamless gutters and covers all around the home).  What should I do now?  Should I check the insulation in the attic?  How do I measure it or determine what to do?  I am such a non-handyman that I really don't have much faith in myself when it comes to my home.  I would truly appreciate your wisdom and insight with this matter.

Thank you for your time.

Dan Crofoot


Hi Dan,

Let me answer this with a few different ideas for you.

Abnormal amount of icicles this week (12/5/09)? Yes - 1) There was no snow on the roof so the shingles absorb more heat so the wet snow that fell melted and created more icicles. 2) Also, the snow started during the day, not night so again, increased roof temp.

What to do next? 1) You can check to make sure you have 15-18" of insulation.  2) Check to make sure that the insulation is not blocking the soffit vents (those are the vents in the overhang of the roof that let cold air into the attic.  Then that cool air helps dissipate warm air that sneaks through your insulation from the house and goes out the ridge vent or the gable end vents.)  If the vents are covered the warm house air melts more snow...and obviously you'd gain from the energy efficiency.

Dan, great job with the roof rake when snow builds up.

Take care and thanks for listening to the show! -brt

Topics: On the Radio, ice dams, icicles, insulation, winter, roof