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Keep an eye out for ice dams

February 14, 2009|By DWIGHT BARNETT / Scripps Howard News Service

Q: During the recent severe weather, we had water running in through the ceiling of our bay window. The power was off for several days and I'm worried about mold and any other damage we may not be able to see. The ceiling and wall will have to be replaced, but what about the wood inside the walls? Do you have any suggestions? -- J.H., Evansville, Ind.

A: I'm old enough to remember ice storms and snowstorms that caused major property damage and inconveniences, but none compare to the winter storm of 2009. When the snow accumulates on the roof and the outside temperatures remain below freezing, an ice dam can form at the bottom of the snow pile.

Here's what happens: warm air currents from the heated side of the attic warm and melt the bottom layer of the snow pack. The melted snow (water) runs down the slope of the roof until it is past the warmer areas, where it refreezes under the snow pack, thus creating a dam of ice. As new water continues to flow, it reaches the dam and floods the roof's shingles. Shingles are designed to shed water, but they cannot resist constant flooding. Water will penetrate the seals of the shingles and the second barrier of felt paper under the shingles until the roof begins to leak.

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Fortunately, most of the leaks occur in the roof's unheated overhang (soffit) area, which is beyond the finished areas of the home. Examining the roof's overhang, you may notice icicles hanging from the vented portions of the soffits. This is a good indicator that you have ice damming, which needs to be cleared before the roof leaks to the home.

A bay window that protrudes past the home's exterior walls is also subject to ice damming of its exposed roof area. Water can even enter through the exterior siding or veneer above the window where the ice dam forms. The major concerns with a leak to a wall and ceiling are mold growth; wet insulation, decay of water-damaged wood and water-saturated drywall are breeding grounds for mold spores.

For one to properly inspect and to make repairs, the damaged sections of wall and ceiling coverings need to be removed. After the wall and ceiling insulation has been removed, the exposed wood framing can be dried using fans or dehumidifiers. Once the wood has dried, it will naturally resist the growth of mold spores.

After the drying has been completed, new insulation can be installed and the wall and ceiling coverings replaced. The wood sections of the bay window need to be monitored as the repairs progress.

If the window has received substantial water damage, the wood may warp or cup as the wood dries. To prevent future ice damming, have a roofer install a product such as Grace's Ice and Water Shield or GAF's StormGuard when the roof shingles are to be replaced.

The shield adheres to the roof's decking and extends 4 feet up from the edge of the roof. The shield can also be installed over the bay window and up the exterior wall if the home has a siding material that can be removed and replaced.

Q: We have just built a new home with a 48-inch range, with a manufacturer's recommendation of a range hood with 1200 cfm. We are finding that in this extreme cold weather that the cold air is just drafting in through the hood. Any recommendations?

A: The seals around the metal ducting are leaking air or the hood is not properly insulated or both. The other problem could be an open or damaged damper. There should not be a draft when the hood is not in use.

Dwight Barnett is a certified master inspector with the American Society of Home Inspectors, e-mail him at d.Barnett@insightbb.com.

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