Learn How to Prevent Ice Dams and Get Ahead of the Cold
Put the heat to your roof’s icy nemesis and say goodbye to ice dams for good
You might think rivers and lakes are the only places where ice dams form, but they’re a common problem for many homes once cold weather settles in. These winter formations can wreak havoc on your roof, damaging shingles and gutters. If left unchecked, they can lead to expensive water damage inside of the home, too.
When you’re looking at how to prevent ice dams, start with a thorough inspection of your attic, vents, and roofline. A few small changes can slow icy buildup and help you eliminate or, at the very least, minimize damage. Keep reading to learn a few different ways to keep ice dams from bending gutters and tearing through shingles.
What Is an Ice Dam?
Ice dams form when accumulated snow on the roof melts. The runoff, which typically hides beneath a layer of still-frozen snow, freezes at the edge of your roofline as it hits cold air. The ice can fill gutters, causing any additional melting snow and water to get backed up at the dam.
The process may continue as the outside temperature stays cool and areas of the roof get warm enough to melt the underlayer of snow. As the dam grows, the water trapped in the ice dam may creep under shingles as the water stagnates and freezes.
Water damage can extend to the interior as water softens roofing materials and makes its way through seams to leak into the attic, walls, soffits, and ceiling. In other words, ice dams can also cause a roof leak. The signs of interior water damage from an ice dam may include peeling paint, water stains around doors and windows, sagging drywall, or rust on drywall fasteners.
What Causes Ice Dams?
Ice dams are a result of a combination of cold outdoor temperatures and a warm attic. As warm air filters into the attic from the living space below, the warm air rises, causing different areas of the roof (usually near the peak) to warm up.
The warmer temperature melts the underlayer of snow on the roof. The melted water runs toward the edge of the roof, where it hits cooler air and freezes in gutters and at the edge of the roofline. Over time, the ice can fill gutters at the roof’s edge until it creates a dam that prevents water from draining through the gutters.
Snow may hide the building dam. In the meantime, the melting-freezing process continues while water continues to build and damage the roof until the weather changes or you remove the ice dam.
How to Prevent Ice Dams
A combination of issues can contribute to ice dams. Preventative measures that include preparing the attic, ceiling, and roof for appropriate ventilation are key. However, you may need to use methods that prevent snow buildup, too.
Seal the Ceiling
These measures can keep warm air from penetrating the ceiling and heating the attic. You don’t necessarily want an airtight house, but if you can prevent warm air from getting into the attic, you can prevent problems with ice dams.
Seal Attic Hatches and Whole-House Fans
Seal your attic access points to prevent heat from escaping into the attic. Cover attic hatches and whole-house fans with weather-stripped caps that keep heat in your living space and help maintain cool attic temperatures.
You can also attach fiberglass or rigid foam board to the back of the attic hatch for added insulation. Think of the attic hatch as you would your front door. You wouldn’t leave your front door open when temperatures are below freezing. Similarly, you shouldn’t leave your attic hatch open or unprotected during cold weather.
Ventilate Through the Roof or Walls
Ducts for the kitchen, dryer, and bathrooms need to vent to the outdoors through the walls or roof. They should not exit through the soffit, where they can cause heat to accumulate in the attic.
Install Sealed Can Lights
Update recessed lights with sealed can lights. You can’t insulate recessed lights, and they can release heat into the attic. A combination of IC fixtures and insulation works well to prevent the heat from sealed can lights from accumulating in the attic.
Prepare the Attic
Before the cold weather and snow set in, take some time to check and prepare your attic. Here are things you can do to prevent damage before it begins.
Find and Caulk Places of Penetration
Take a walk through your attic, looking for places where warm air may escape into the attic. Look for stained insulation, which can be a result of air passing by the insulation. Light penetrating into the attic can be another indication of air leakage.
Seal areas around vent pipes and electrical cables with fire-stop sealant. You can also use caulk to seal around electrical boxes.
Keep Eaves and Ridges Ventilated
Make sure you’ve got appropriate ventilation at the ridge and soffit. If there is a blockage or inadequate ventilation, it can let the warm air build. Ridge and soffit vent openings are equal in size and should leave an opening of at least 1 square foot for every 300 square feet of attic floor. Baffles placed at the eaves can help maintain airflow at the soffit vents.
Add Insulation to the Attic Floor
Inadequate insulation on the attic floor can also be an issue. Check the building codes in your area to see if your attic is under-insulated. If you’re still not sure, consult a local insulation pro to see what you may need and to get a quote.
Install Flashing Around Chimneys
Leaks can easily occur between the chimney and the house frame. Close the gap with L-shaped steel flashing. Use fire-stop sealant to hold it in place. Make sure to use canned spray foam to ensure the fire safety of the insulation.
Insulate HVAC Ducts
Leaky HVAC ducts can also be an issue. Apply fiber-reinforced mastic air duct joints and add exhaust ducts. You can also use R-5 or R-6 foil-faced fiberglass to cover the joints and keep heat inside. This process can be labor intensive, but you can DIY duct insulation if you want to save money, or call an HVAC pro if you’d rather leave the job to them.
Blow Cold Air at the Point of Penetration
You can’t necessarily melt ice dams from inside, but you can freeze the water they let inside. If you’ve got water leaking into the attic, place a box fan in the attic and aim it directly at the point of water penetration. The added airflow can freeze the water and prevent further damage.
Rake Off Snow
Use a snow rake or push broom to remove snow from the roof. Less snow on the roof means less runoff and less potential for an ice dam. Be safe, and don’t stand directly underneath the area of the roof you’re raking. Falling ice and snow can be dangerous.
Install Heated Cables
In some cases where other ice dam prevention methods don’t work, you can install heated cables at the edge of the roof line. Zigzag the cables and attach them to the roof. The heat at the roofline prevents ice from forming so the water can drain through the gutters. Keep in mind that your electric bill will go up with this solution, and your curb appeal might go down.
Apply Ice Melt to the Ice Dam
Place ice melt tablets, not rock salt, in an old sock or pantyhose and lay it directly on the ice dam and over the gutter to melt ice in gutters. It then helps melt the ice and allows water to drain. Don’t place the melt tablets directly on the roof or gutters, as they can cause damage, and runoff may harm landscaping or animals.
DIY vs. Hiring a Pro
Snow removal and ice damage management can be dangerous. Winter roofs covered in snow and ice can easily lead to slipping and falling off of the roof. Ladders are risky in the winter for the same reasons.
If you stay on top of the snow removal (from the ground with a snow rake), you probably don’t need to hire a pro to help with ice dams. However, if you need structural work done on your roof or attic, a contractor can make the needed structural repairs and make sure all construction is up to code.
If you’re unsteady on your feet or you don’t have the right equipment, call a local snow removal company. Professional ice dam removal can be pricey because of the high cost of insurance for such a dangerous job. However, pros can use equipment like steamers that convert cold water into low-pressure steam to melt snow and ice. They also have experience with removing the ice without further damaging gutters and roofing, which can make the cost of ice dam removal worth it.
Frequently Asked Questions
While installing a new roof means saying goodbye to previous damage, it may or may not help prevent future ice dams. Standing seam metal roofs and drip edges are less susceptible to ice dams, but they’re no guarantee that the same problem won’t occur. Ice dams are caused by what’s happening inside of the house more than by what’s happening outside. If the attic doesn’t have adequate ventilation or the ceiling leaks into the attic, a new roof won’t make a difference.
Avoid putting salt on your roof to prevent ice dams. Rock salt, for example, melts ice at temperatures between 20 and 32 degrees Fahrenheit, which aren’t temperatures that generally contribute to ice dams. It’s when temperatures fall below 20 degrees Fahrenheit that the discrepancy between the outside and attic temperatures becomes more of an issue. Additionally, the salty runoff can damage roofing and potentially harm plants and animals.