Don’t let ice dams wreck your winter
Tips for prevention and removal
As much as we might complain here and there about our Minnesota winters, there is something idyllic about the sight of your home, roof padded with snow, a cascade of icicles hanging from the eaves.
That is until you go inside and find water running down the walls and pouring out of the light fixtures.
You have ice dams.
What are ice dams?
They are a ridge of ice that forms along the eaves of your home. When temperatures rise enough to cause additional melting, a pool of water forms behind this ridge. Since your roofing materials are meant to shed water, not hold water, it works its way through the roofing materials and comes inside.
What causes ice dams?
The primary culprit is lack of insulation. Many of the older homes in Minnesota are under-insulated, or have bypass issues that allow heat loss from the home’s interior to escape into the attic. Once the attic space is warmed, the snowpack on the roof melts from underneath and the water runs to the eaves where it is still cold and it refreezes. This process continues until a ridge of ice forms, causing the water running downslope to pool behind it. Another contributing factor is the freeze/thaw cycle that occurs daily in late February and into March. The temperature rises above freezing during the day, and drops below freezing at night.
Ice dams form on many houses. When we experience a heavy snowfall followed by a warmer thaw/freeze cycle, they can form on any house. The damage they can cause is the primary concern. Modern roofing materials make use of a special underlayment called Ice and Water Shield that prevents water intrusion. Ice dams can still cause damage by pulling down gutters or tearing shingles when ice breaks free. Older roofing materials will have the risk of water intrusion which causes the most damage, as it can saturate building materials, damage finishes, and possibly lead to mold and fungal growth.
Removing Ice Dams
Once ice dams have formed, you’ll want to remove them fairly quickly to reduce your risk of water intrusion. Your best option is to hire a professional with a steamer to cut the ice off your roof. They use specialized equipment that generates low pressure steam at about 320 degrees F to remove the ice with little to no damage to your shingles. The downside to hiring a professional is that it can cost in excess of $1500 for the service. If you don’t have water coming in, but are worried about the size of your ice dams, you can purchase salt pucks that you can toss onto your roof behind the ice dam. The salt will melt channels through the ice to allow water to drain away, though the salt can be harmful to your roofing materials long-term and can damage landscaping.
Never use mechanical means to remove the ice dams. We have seen many roofs with hatchet marks through the shingles where ice dams were removed by force.
If your home is prone to ice dams and you want to get ahead of the issue, you have several options.
- Better insulate your attic space and close off areas of attic bypass such as around light fixtures, unsealed attic hatches, exhaust fans, wall chases around waste vent pipes and chimneys.
- If your roof is due for replacement, you might consider retrofit panels. They are an insulated panel created with high density foam glued to plywood. When you deck your roof with these panels before installing new shingles, you create a thermal break that stops interior heat loss from melting snow on your roof.
- You might consider installing ice melting cables. They cost about $1/foot and can be easily installed by yourself or your favorite maintenance pro. Melting cables are installed in a zigzag pattern along your eaves. They melt channels through the ice to drain the melt water. Melting cables can be found at almost any hardware store, but should be installed before the winter season.
- The final and least costly option for prevention is roof raking. This is where you physically remove the snow from your roof with a specialized roof rake so that it cannot melt there. There are two types of roof rakes available. A traditional roof rake will be plastic or metal and will have several extension poles so you can reach most of your eaves from the ground. You hoist the rake up to your roof from the ground, position it above the snow pack, and pull the snow down. The second type of roof rake is the “Avalanche” roof rake which has a long sheet of plastic that acts as a slide for the snow. This is a push-style rake that goes under the snow pack to cut it loose. The snow slides down the plastic slide. This style roof rake is much less labor intensive.
If you are concerned about ice dams right now, get yourself a roof rake (they cost between $100 and $150) so you will have one on-hand to remove snow before ice becomes a problem. If you already know ice dams are a problem for your home, install melting cables and look into improving your attic insulation. If you have an emergency with water coming in, call your insurance company and they’ll send a professional out immediately!