It is the time of year that you may notice the accumulation of icicles and ice dams on your roof eaves. These large icicles forming on the roof edge and gutters are a sign that your attic is improperly insulated, and more importantly, warm air you are paying for is leaking from your home and is instead warming areas of your attic space.
The Weatherization Program of the Social Development Commission says ice dams form at roof eaves or roof overhangs where the warmer interior roof areas meet the unheated exterior roof overhangs. Snow on the roof deck melts and re-freezes at the colder temperatures at the edge of the roof. This cycle continues until an ice dam forms, which can trap water on the roof and in gutters. This trapped water can cause severe damage to the roof deck if not properly protected. This water can migrate into the exterior wall or ceilings if the condition worsens. With nowhere to go, the water can melt and re-freeze, causing major damage from the ice dams and icicles.
Heat always travels to cold areas of a home. Insulation is designed to slow this heat transfer process through the ceiling into the attic. The attic space is designed as a “buffer zone” between the heated living areas and the much colder outside temperatures. The attic insulation can only slow the transfer of heat to the attic. Some heat will inevitably transfer from the house to the attic because of the temperature difference.
Many times a roofer will recommend the installation of additional roof vents to ventilate moisture from the attic to address the ice damming. SDC Weatherization staff warn this is typically not the correct solution! Adding more ventilation can accelerate the process of warm air escaping into the attic and can actually magnify the issue.
Air leaks, even in well insulated attics, can exist in the original framing and construction of your home which allows the warmed air to leak through the insulation to warm areas of the roof deck from below. These areas of leaks can easily be identified right after a fresh snow where you can see only certain areas are melted on your roof. This is a good way to spot where there are “bypasses” or major air leaks before entering into your attic. The gaps can occur at chimneys, dormers, soil stacks or electrical boxes in the ceilings.
These are the first problems to address in preventing ice dams. Seal the leaks first to prevent the rapid loss of heat, and then assure that the proper thickness of insulation is in place in the floor of the attic. For our climate, R38 to R50 thickness insulation is recommended.
Do it yourselfers can make these necessary corrections by sealing the bypasses and increasing insulation values in their attic space to prevent the effects of ice damming. SDC’s Weatherization Program also performs energy saving measures for low-income individuals in Milwaukee .
See the SDC Weatherization Facebook page for this topic and other tips on how to safely keep your home warm this winter. Just check out the Discussions page for a wide range of important information including avoiding carbon monoxide dangers, how to reduce drafts around windows, and saving money by changing your light bulbs.
