by Nicki Campbell

The massive snowfalls we have been experiencing over the past few weeks have turned Central Ohio into a winter wonderland.  Icicles hanging from trees create a magical effect, especially when the sun comes out (this actually happened on Sunday!) and makes the icicles sparkle.

But what about the icicles that are hanging from the eaves of so many of our homes?   Far from being magical, these can be signs of a phenomenon known as "ice damming", which can cause minor or major leaks resulting in roof and insulation rot, ceiling and wall damage, attic flooding, mold and more.

Ice dams usually occur after a heavy snowfall and several days of freezing temperatures.  Warm air that builds up under the roof or in the attic will heat the underside of the roof causing the snow or ice on the roof to melt.  The resulting water runs down the roof under the snow until it reaches the roof overhang, which is very cold.  The melted water then refreezes and forms a dam of ice, behind which the water ponds.  This ponding water can back up under the roof covering and leak into the attic or along the exterior walls.

Prevention

The way to prevent ice dams is to keep the entire roof of the house the same temperature as the outside, or the eaves.  This can be accomplished by increasing ventilation, adding insulation and sealing off every possible air leak that might warm the underside of the roof.  The general recommendation for proper insulation is 1 square foot of vent for every 150 feet of attic floor area.  (This can vary according to area of the country.)  Some experts recommend installing an electric vent fan that works on a thermostat.  The fan will pull outside aire into the attic to keep the inside temperature consistent .

What Not to Do

  • Do not try to "chip away" the ice.  This commonly leads to shingle or gutter damage.
  • Do not install heaters or mechanical equipment in the attics.
  • Do not use salt or calcium chloride to melt snow on the roof.  These chemicals are corrosive and can damage metal gutters, downspouts and flashings, as well as nearby grass and plants.
  • Do not get on the roof to try to remove snow or ice.  This can cause roof damage and it is not safe for you!

What to do if ice dams are causing water damage (short term solutions)

  • Hire a qualified contractor to carefully remove most of the snow from the roof above the ice dam.  He should not touch the roof with equipment or walk on the roof, if possible.  Cold roofs are brittle and are prone to damage. The contractor may decide to create one or two grooves in the ice dam to allow the ponding water to drain off. 
  • Make a "snow melt sock" by cutting the legs off a pair of pantyhose, filling with calcium chloride ice melter and laying it onto the roof so it crosses the ice dam and overhangs the gutter.  This should melt small channels in the ice, allowing runoff to occur.

For more information, the University of Massachusetts has an excellent article at  http://bct.nrc.umass.edu/index.php/publications/by-title/preventing-ice-dams/. 

Other sites with information are:

http://htoyh.com  (Mr. Fix-It Home Tips)

http://diylife.com

http://thisoldhouse.com

Although we believe this information to be reliable and accurate, we cannot guarantee it.  As always, consult an experienced contractor or other expert to determine the best solution for your individual situation.