When the house roofs pile up with sleet, snow, and frozen rain, an ice dam’s chances become very real. Unsuspecting homeowners may not understand what is going on. The roof can be brand new last year, and if the circumstances are exactly perfect, it can rain inside your house like there is no roof at all. In the northern climates, many folks know this all too well. Here in the South, we experience this type of weather every 5 years? Perhaps 10 or more? So we are less aware of this issue.
Allow me to set the stage. The leak comes from what is commonly known as an Ice Dam, which needs to have the right conditions to happen. The first issue is the insulation in your attic. The space directly under your roof is referred to as attic space and is not designed for people to live in. This makes it a great spot to add insulation to the floor, or usually, it sits just above the drywall ceiling. Most insulation settles and breaks down over time and becomes increasingly less effective as the years go on. This allows the heat from inside your home to escape into the attic. The next issue is the outside air temperature. This can be a problem around 32 degrees. Plus or minus several degrees, either way, add some sunlight, or not as the case may be. As the attic temperature rises, it starts to melt the snow, which then runs down the roof. It’s a roof, and this is what happens every time it rains, right?
Once the meltwater reaches just about the soffit area, the warm water meets the unheated soffit area. This spot is usually much cooler. The snow will melt much slower at the roof’s very bottom edge, near the gutter, when the roof extends past the heated wall of your home. Under the right conditions, it will not melt at all in that location. Then the meltwater will refreeze. But it does not stop there, and the dam continues to build until it becomes a literal ice dam. Eventually, if this persists, the water level becomes deep enough to start leaking back into the house.
A shingle roof is not waterproof. It is actually shed water. Shingle roofs are very efficient at getting the water to run away or off of them. To have an actual flood situation only on the roof is rare. However, that is what we are discussing here.
What’s the solution? First, if this is happening to your home, do not go on the roof. It’s icy. This will not end well. Call a roofing contractor. They will know exactly what to do. If you call one and do not know what you are talking about, hang up, call another. The dam needs to be broken, to let the water off the roof. The snowpack needs to be removed, and the water will drain. Your gutters may be frozen solid, and this can be an entirely different leak coming from a very similar set of circumstances.
After the leak is stopped, an evaluation of the insulation, ventilation, roof, and gutters need to be done. R-38 is the minimum recommended insulation amount. Your local codes may be different. A quick call to your local building code office will help you find the correct answer. They will know. Added ventilation can help. In an ice storm, the vents can be covered over by ice and not allow any ventilation at all.
For more information, the Nation Roofing Contractors Association or NRCA is the premiere roofing authority on all things roofing. They helped write the codes, advise roofing contractors, and homeowners alike. https://nrca.net/press-room/press-release-archive/1119-avoid-roof-damage-winter