Real Estate: Winter water damage from ice dams, attic condensation

By Tricia Zwirner

Excessive snow on the roof, condensation in the attic and ice buildup can cause roof and water damage. What are ice dams? What causes attic condensation? Why is excessive snow on your roof a concern? And what to do if you’ve had these?

What are ice dams?

When the temperature in your attic is above freezing, snow on the roof will likely melt. When the snowmelt runs down the roof and hits the colder eaves, it refreezes.

If this cycle repeats over several days, the freezing snowmelt builds up and forms an ice dam, behind which water pools into large puddles, or "ponds." The ponding water can then back up under the roof covering and leak into the attic or along exterior walls.

The right weather conditions for ice dams are usually when outside air temperatures are in the low 20s (°F) for several days with several inches of snow on the roof.

Causes of condensation in your attic

Attic condensation typically occurs when warm, moist air migrates or is directed into the attic from living spaces below. Research indicates unusually high humidity in the home's living spaces is strongly associated with attic condensation problems.

Winter water damage warning signs

Recognize the signs of stress when too much snow and ice has accumulated on your roof or when you have too much condensation in your attic.

Here are a few things to watch for:
Sagging ridgeline
Drooping ceilings
Water leaks on interior walls and ceilings
Jammed doors
Cracked interior walls near the center of your home
Creaking sounds

Condensation, snow on roof and ice dam prevention tips

Building codes attempt to prevent these problems but they can't address it all. And many houses could have been built prior to their creation.
Bathroom and kitchen exhaust fans and dryer vents should never be discharged into the attic space and always discharge outside. You may have an adequately ventilated attic, but this won't matter if the bathroom exhaust fan dumps warm moist air directly into the attic space. This could result in condensed water vapor freezing onto cold attic materials, which will eventually thaw creating wet attic materials resulting in damage and potentially mold in the attic and inside the home.
Minimize ceiling mounted fixtures below the attic that create the need for holes in the drywall or plaster ceiling. Properly seal ceiling penetrations to make them airtight taking care to follow manufacturer clearance requirements for flues, chimneys and recessed light fixtures.
Research shows keeping the attic air temperature below freezing when the outside air temperature is in the low 20s can reduce the occurrence of ice dams. Proper attic ventilation is key to keeping the attic cool, while adequate and properly installed insulation is key to keeping your house warm. It is critical to keep soffit vents free from obstructions to allow the natural flow of cool outside air into the attic space to replace the warmer attic air that rises and flows outside the ridge and/or roof vents. This flow of air will keep the attic cool and free of moisture build-up.

What to do
It’s recommended you hire a professional contractor to be sure that insulation in the attic space is adequate to help prevent your home's warm air from escaping into unheated attic spaces.
Remove snow from the roof to prevent the creation (or reduce the impact) of ice dams. A "roof rake" can be used to remove snow but may damage the roofing materials so be very careful or hire a professional if in doubt.
Verify soffit and roof or ridge venting exists for all roof planes and that soffit vents are neither blocked by attic insulation nor covered by newly installed maintenance free finishes outside the home.
Verify all penetrations, access panels and electrical fixtures are properly sealed and insulated to prevent heat and moisture from entering the attic space, while maintaining manufacturer's required clearances.
Verify all exhaust fans and dryer vents are discharged to the outside.
Keep gutters clean of leaves and other debris. This will not necessarily prevent ice dams, but clean gutters can help drain away ice melt as it makes its way to the gutters during a thaw.
Follow up a short-term ice dam remedy with determining and fixing the actual cause to your ice dam problem. Consult a trusted and competent professional.
If replacing your home's roof, have a self-sealing membrane installed under the shingles to help prevent water damage from ice dams.
On metal roofs, install snow guards above entrances.

If your home suffers damage this winter, contact your homeowner’s insurance agent to see if it's covered under your homeowner's policy. <

Tricia Zwirner is a State Farm agent celebrating her 21st year in Windham. She and her team would love to hear from you and can be reached via phone and text at 207-892-2864 or via email at tricia@TRICIAZWIRNER.com.