Winter is fast approaching and one of the most annoying (and sometimes extremely expensive) maintenance issues for homeowners is those pesky ice dams. You know, the pretty icicles that build up on the eaves and overhangs of your house. Technically speaking, an ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from draining off the roof. It is the water that backs up behind this dam that can infiltrate into the home and cause serious damage to the insulation, sheetrock (walls and ceiling), decorative trim and wood flooring. Water trapped in the walls can also grow mold and mildew causing a variety of health issues.
So what causes an ice dam? In the simplest terms, it is non-uniform surface temperatures on the roof. Heat from inside the house is transferred to the roof surface through gaps in insulated portions of the structure by convection, conduction and radiation. Another big source of heat loss is through air infiltration. Classic areas of trouble are found with recessed lights in a cathedral ceiling, skylights and poorly vented and flashed roof eaves.
There are two kinds of solutions, short term and long term. Short term solutions like roof rakes and heating coils can help, but they don’t get to the root of the problem. Also, be careful, if executed poorly these solutions can damage your roof. Long term solutions address the causes of ice dams, namely poor insulation and air leakage. Blower door tests and radiation cameras are useful tools in assessing these issues. Increased insulation, air infiltration barriers, waterproof membrane flashings, proper ventilation are all methods of solving this problem. Remember that each situation is unique. Consulting with an Architect will help to find the solution right for you.