Ice dams can form on roofs after a heavy snowfall and can cause serious damage to your home if you do not take precautions. Heat from the attic causes the snow to melt, but the water does not flow off the roof. Instead, the water refreezes when it reaches the cold edges of the roof. Eventually, a mound of ice forms and meltwater pools there. This water seeps back under the shingles as far as 10 feet, drips into the soffits that overhang the walls, and penetrates the structure.
The worst part is that you probably won’t realize something is wrong until you see water stains around windows or doors, peeling paint, or rust spots after the water oxidized the metal in nails, screws, or fasteners. Often times, water also causes mold and mildew issues which can cost tens of thousands of dollars to remedy, never mind the hassle.
Fortunately, ice dams are relatively easy to prevent. Since a warm attic melts the snow, one of the first lines of defense against ice dams is a cold attic. If the attic in your home is warm, you need to stop heat from reaching it. It will also lower your heating bill, because you’ll only heat your living area.
Plug the Gaps
Access your attic and plug all leaks using spray foam, caulk, or insulation. If you have an attic hatch, you should cover it with a cap made from foil-faced foam board and aluminum tape.
Ensure your gas, oil or propane-fired water heaters and furnaces vent properly to avoid deadly carbon monoxide fumes. Kitchen and bathroom ducts and dryer vents should vent through the walls or roof, not the soffit.
Top Up Insulation
Check to make sure that you have sufficient insulation in your attic. According to Energystar.gov, if your insulation is just level with or below your floor joists you should add more. The recommended level is R-38, or an even layer of about 10 to 14 inches. You can use fiberglass batts without backing, but blown-in cellulose and fiberglass leaves fewer gaps. Do not block air vents.
Ventilation in the attic draws in cold air and pushes warm air out. This cools the attic so ice dams do not form. You need a minimum of a 1 sq. ft. vent per 300 sq. ft. of attic floor area. This usually translates to an 8 x 16-in. vent in every other rafter space in the soffit or a strip vent along the length. You will also need a ridge vent along the peak. Consider hiring a professional, especially for odd-shaped roofs. The work is dangerous and you may not have the equipment or expertise to safely tackle it yourself.
Install Ice & Water Barrier When Re-Roofing
If it’s time for a new roof on your home, ask your contractor about an adhesive ice and water barrier. It’s a special underlayment around the edge of the roof that prevents water from seeping into the structure.
Rake Off Snow
If you live in a single story home, you can buy an aluminum snow rake with a telescoping handle. When you remove the snow, it can’t melt or form an ice dam. However, you need to tread gently on brittle roof shingles or you could cause damage.
Install Heat Cables
If all else fails, you can mount heat cables in a zigzag pattern to the edge of your home’s roof and a downspout. These cables plug into an outdoor GFCI receptacle and melt the ice dam, but you must ensure the meltwater drains towards the heated downspout. Otherwise, the water will freeze again.
Steam It Off
If you notice an ice dam you can hire a roofing company to steam it off. They use a machine like a pressure washer with hot water. It will eliminate the immediate problem, but not what causes it. You’ll still need to prevent more ice dams.
Don’t ignore ice on the roof. Discover what’s causing it and remedy it. Removing and preventing ice dams can help you avoid costly damage to your home, an insurance claim, and increased home insurance premiums.