An ice dam is a build up of ice at the edge of the roof. It is called a dam, because the build up is large enough to dam up some water behind it. Sometimes even the best roof designs can get them. This winter it seems every roof has had one. But generally it is caused by a warm attic and cold eaves. That allows the snow to melt up on the roof over the attic, and then refreeze when the water reaches the eaves. The eaves are cold since they are not over the house, but are hanging out there in the cold. If the ice doesn't fall off the roof, and hangs on, then the water melting above, will build up behind the ice. Damage that can be done is water that is building up behind the dam can get high enough to get under the shingles and leak into the attic. It often shows up as water leaking from the window trim or wet spots in the ceiling close the walls. If it happens once it can stain your woodwork, and make those ugly water marks on your drywall. If it happens often it will rot the roof decking, and other framing members.
Adding insulation to your attic floor will help, not only will it cut down on ice dams but also cut back on your heating bill. Ventilation is important for many reasons. Key among them is the elimination of moisture that finds its way up to the attic. Moisture that makes its way to your attic will condense in the cold air. It will condense on your plywood roof decking and cause it to rot and it will pass up through the shingles causing them to fail years before they should.
Either you have a lot of insulation and ventilation and you still have ice dams, or, you have cathedral ceilings or a roof attic design that makes adding those impossible. In that case you can have an ice belt installed. An Ice Belt is Metal flashing installed all the way along the eaves and extends to the area of the roof above the attic. It covers the area where the ice will form. It serves two purposes, first it provides a surface which permits the snow and ice to just slide off preventing most dams. Second it provides a surface that water won't flow up under as it as it does with shingles.
As always give Fauser Home Improvement a call at 309*792-3122 or visit us anytime at
www.FauserHI.com!