What Causes Ice Dams in Ann Arbor, MI?

What Causes Ice Dams in Ann Arbor, MI?

Many homeowners are experiencing large ice dams and icicles along the eaves right now and if questioned on it – most would be hard pressed to explain what is going on and why it is happening.

Many homeowners blame their gutters which are full of ice and have become ice trays and they may be right or partially right – although you can have icicles and ice dams and not have gutters on the house.

There are three main reasons that contribute to ice and ice dam formation on the eaves of residential homes.

1. Home Design. The way we design and build homes in this country does not allow adequate space at the eave area to insulate and ventilate . The triangle formed from the intersection of the roof line and attic floor line is too constricted to insert enough insulation to yield an R-60 (17”) which is what the Federal requirement for Michigan Attics.
2. Gutters. Gutters are designed to fail and do so with striking regularity. When they are not cleaned often enough leaves and debris will occlude the downspouts, which will contribute to clogged gutters and standing water which will freeze in winter and will then build up upon itself filling the gutters and then back up upon the eave and shingles.
3. Lack of Insulation and Ventilation contributes to heat loss, manifested by the presence of icicles, ice dams and shingles visible through snow melt on the roof.

Contributing Factors

There are a number of factors at work that contribute to the formation of ice and dams.

Here are some of them.

• Direction the House Faces
• Direction of prevailing Winds
• color and type of shingle or roof material
• type and size of overhang
• type and amount of soffit ventilation (intake)
• type and amount of ventilation (exhaust)
• type and amount of insulation
• sources of heat loss into the attic from living quarters
• size and condition of gutters and downspouts
• presence of lack of ice and water shield

Potential Serious Problems

Here is a short list of potential problems caused by ice and icicles at the eave.

• damage to gutters and downspouts as ice expands and contracts
• damage to shingles with ice working up under and over them causing cracks
• roof leaks when ice builds in gutters and works its way up underneath the drip edge and melts
• roof leaks when ice melts forming pools of trapped water behind the ice dam
• safety issues to occupants and visitors

Solutions

1. Re-designing and rebuilding the eave area and pulling up the roof to add insulation in cathedral or vaulted ceilings are solutions but impractical.
2. Adding Heated Helmet electric wire to gutters and Gutter Helmet will substantially Reduce ice and ice dam formation at the eave.
3. Adding insulation and or ventilation is the quickest, easiest and most cost effective means to deal with the heat loss issues which contribute to icicle and ice dam issues.