Winter is here, and so is the potential for ice dams. It’s one thing to have icicle formation after some warm weather, but quite another if these icicles are a result of ice dams. To reduce the potential for damage to your home, it’s important to understand how ice dams form, how they can impact your home, and methods to prevent them from forming.
Ice dam at the roof edge
What is an ice dam?
Icicles can form at the bottom edge of a roof line or on gutters when water gets cold enough to freeze. If water is running down your roof and it is at or near freezing, the water that drips off the edge starts to form icicles.
As gutters fill and freeze, they become heavy and can cause damage to your gutter system. If the water continues to build up, it creates an ice dam at the eaves, which will not allow water to flow over the edge of the roof. This water can find its way under the roof coverings and into your eaves, or worse, your walls and ceilings.
Icicles and ice dams are a sign of a larger problem with the house. When the roof covering is warmer than the eaves, even in below-freezing temperatures, ice dams can form.
What are the main causes of ice dams?
The two main causes of ice dams are poor insulation and inadequate ventilation in the attic space. If your home has minimal or poor insulation, heat from within your home will rise into the attic space and warm the roofing materials. Snow on those surfaces will melt and flow to the edges of your roof. The overhangs on your roof will be colder than the attic space. Once that water hits the edge, it will start to freeze and build up.
How an ice dam forms
Inadequate ventilation will result in condensation building up on the bottom of the roof decking. Moisture from inside your home will find its way into the attic space. Condensation on the roof decking and structural materials may cause staining and/or moisture damage.
Our home inspectors will look for signs of moisture staining and evidence of ice dams when performing your home inspection. In the winter, when we're inspecting an attic space, we often see frost on nails and other metal fasteners where there may not be adequate ventilation.
On one home inspection years ago, I saw icicles in the attic space of an older home that had very little attic space ventilation. Photos were taken, and the condition was noted in the home inspection report.
How can I prevent ice dams?
Most times, this issue can be resolved fairly easily. The best course of action to prevent ice dams would be to increase the insulation and improve the ventilation in the attic space. If the roof is not warm, the snow that falls on it will not melt easily. The best-case scenario is for the roof to be at a temperature matching the outside air. This keeps snow from melting and refreezing at the eaves.
Some older homes do not allow for additional insulation in the area where the exterior wall meets the slope of the roof. If this is your case, you might try one or more of the options below.
Sometimes, heating tapes or cables can be installed to melt ice dams at the eaves and create pathways for the water to flow from the roof. Adding heating tapes or coils addresses the symptom but not the conditions that create the ice dams. Again, your first course of action should be to review the insulation levels and ventilation of your attic space.
Another measure of prevention is to use a roof rake to pull fresh snowfall from the eaves of your home. Pulling the snow from the eaves will allow the sun to keep this part of your roof warm, thus helping to reduce ice dams. You will want to be extra careful not to damage the roof surface when using a roof rake. Again, however, this does not resolve the root cause of ice dam formation.
Using a roof rake to prevent ice dams
At HomePro Inspections, our home inspectors are trained to inspect your attic space and identify any defects that may lead to damage. Any issues are documented in your home inspection report and recommended for resolution by a qualified professional.
Visit our website to learn more or to schedule your home inspection in the Rochester, Owatonna, and Faribault, MN areas. You can contact us today at (507) 202-8942 or utilize our online “Schedule Now” feature to set up an appointment.