An ice dam is ice built up near the edge of your roof preventing water from running off of your roof.
The best prevention of ice dams starts with ensuring proper insulation and ventilation of the attic space. But it is December and the snow is here and most people will not have the time to make a repair like this during the holidays and the cold weather. It takes time and needs to be fixed to prevent water damage in the future from ice dams.
For now you can make a habit of clearing the edge of your roof with a snow rake.
What harm does an ice dam cause?
Ice dams hold back water causing water to enter the home by seeping under the shingles. This can lead to many issues such as:
- rotted roof decking, exterior and interior walls, and framing;
- respiratory illnesses (allergies, asthma, etc.) caused by mold growth;
- reduced effectiveness of insulation. Wet insulation doesn’t work well, and chronically wet insulation will not decompress even when it dries. Without working insulation, even more heat will escape to the roof where more snow will melt, causing more ice dams which, in turn, will lead to leaks; and
- peeling paint. Water from the leak will infiltrate wall cavities and cause paint to peel and blister. This may happen long after the ice dam has melted and thus not appear directly related to the ice dam.
How do I prevent ice dams?
- Keep the entire roof cold. This can be accomplished by implementing the following measures:
- Install a metal roof. Ice formations may occur on metal roofs, but the design of the roof will not allow the melting water to penetrate the roof’s surface. Also, snow and ice are more likely to slide off of a smooth, metal surface than asphalt shingles.
- Seal all air leaks in the attic floor, such as those surrounding wire and plumbing penetrations, attic hatches, and ceiling light fixtures leading to the attic from the living space below.
- Increase the thickness of insulation on the attic floor, ductwork, and chimneys that pass through the attic.
- Move or elevate exhaust systems that terminate just above the roof, where they are likely to melt snow.
- A minimum of 3″ air space is recommended between the top of insulation and roof sheathing in sloped ceilings.
- Remove snow from the roof. This can be accomplished safely using a roof rake from the ground. Be careful not to harm roofing materials or to dislodge icicles.