If you live in a snowy cold climate like Rochester NY you have seen ice dams; those bands of thick ice forming along the eaves of houses, and large beautiful icicles hanging from gutters causing millions of dollars of damage every year to home owners.
Water-stained ceilings, missing or dislodged roof shingles, sagging or torn off gutters, blistered or peeling paint, and damaged dry wall are the results of this all too common problem.
You can spend a lot of time and effort trying to treat the symptoms, but in the end, proper air sealing, insulation, and attic venting is the only real way to eliminate the problem.
Ice dams usually form along the roof’s edge, above the overhang. Why? Heat and warm air raising and leaking from the living space below melt the snow, ice water trickles down to the colder edge of the roof (above the eaves) and refreezes. The cycle continues for every inch of snow that accumulates on the roof. Every inch insulates the roof deck a little more, keeps more heat in the attic, which in turn makes the roof even warmer and melts more snow. Freezing outdoor temperatures ensure a fast and deep freeze at the eaves. Perfect conditions for ice dams usually occur when a deep snow is followed by very cold weather.
New gutters will solve the problem, won’t they?
Gutters do not cause ice dams. But, clogged gutters do help concentrate ice and water in the very vulnerable area at the edge of the roof. Gutters filled with ice, often bend and rip away from the house, taking fascia, fasteners, and downspouts with them.
Water leaking into ceiling and wall insulation
Wet insulation doesn’t work well. Water-soaked insulation remains compressed, even after it dries, the R-value is lower. The lower the R-values, the more heat lost. This sets up a vicious cycle: heat loss-ice dams-roof leaks-insulation damage-more heat loss! Cellulose insulation is particularly vulnerable.
Water often leaks down inside the wall, where it wets wall insulation and causes it to sag, thus leaving voids at the top of the wall. Another vicious cycle has started; mold and mildew may form on the surface or interior of the wall. Exterior and interior paint blisters and peels.
Solving the Problem
The way to stop ice dams from forming is to keep the entire roof cold. In most homes this means blocking all air leaks leading to the attic from the living space below, and increasing the thickness of insulation on the attic floor. If you don’t have one, installing a continuous soffit and ridge vent system can be the ticket. Be sure that the air and insulation barrier you create is continuous.
Don’t waste time or money placing electric heat tape on the shingles above the edge of the roof. Electrically heated cable rarely, if ever, solves the problem. It takes a lot of electricity to prevent ice formation; and the heating must be done before it gets cold enough for ice dams to form, not afterwards. Over time, heat tape can make shingles brittle. Other factors to consider are; heat tape is expensive to install, water can leak through the cable fasteners, and often the cables create ice dams just above them.
The worst of all solutions is shocking or pounding the roof by shoveling snow and chipping ice from the edge of the roof. We have seen people use hammers, shovels, ice picks, homemade snow rakes, crowbars, and even chain saws!
When roofer’s see these techniques being deployed, they know they will be getting called more sooner than later.