The Mid-Atlantic region had a “major snow event” last week, and one of the byproducts of all that snow has been a huge ice-dam problem.
How an ice dam works
Ice dams can happen any time snow falls on a sloped roof, especially if the gutters are clogged with debris and the attic is poorly insulated. Heat from the interior melts the underside of the snow pack; this water flows down the roof and is stopped by a buildup of ice at the edge. With nowhere to go, the water pools at the edge and rises under the shingles, where it then can flow down through the attic space and into the ceilings and walls of the house.
Heat from the house can get into the attic several ways.
Houses with very shallow or non-existent eaves are more likely to experience ice dams, as the edge of the roof is directly above the heated living space. Also, if you have recessed ceiling lights, they may also allow heated air to leak into the attic.
Once you have ice dams, there’s not really much you can do about them.
After the snow melts, though, you will need to do several things to prevent them from happening again.
- Insulate the attic, especially at the eaves. Any insulation that got wet from a leak must be removed and replaced. The best thing is to insulate the floor of the attic, so heat from the house doesn’t penetrate the attic. This will also reduce your heating bill. Keeping the attic cold during the winter will prevent the snow on the roof melting from the inside out.
- Keep your gutters clean. Have them inspected and repaired, if necessary. Gutter helmets and other debris guards will not protect against ice dams.
- Have a roofer install ice and water shield underneath the first few courses of shingles on your roof. This will create a waterproof layer of protection for the lower edge of the roof, so any accumulated water that gets under the shingles can’t penetrate to the sheathing.
A waterproof membrane under the shingles can prevent water damage
