Winter up here in Minnesota means ice dams. Every January I get calls from homeowners with water dripping down interior walls, and nine times out of ten an ice dam melter could have stopped it before it started. Let me save you the trip up a ladder.
An ice dam melter is one of the simplest tools for breaking up the ridge of ice that forms along your roof's edge. You've probably seen the big blue pucks or tablets in hardware stores. They're basically calcium chloride packed into a hockey-puck shape. You toss them on the roof, they melt a channel through the ice, and the backed-up water can drain off instead of sneaking under the shingles. I've used them on hundreds of roofs, and they work—if you pick the right one and place it right.
What an Ice Dam Actually Is
Before you throw anything on your roof, you need to understand what you're fighting. An ice dam is a ridge of ice that forms at the edge of your roof. Warm air leaking from your attic melts snow higher up the slope. That meltwater runs down until it hits the cold overhang and refreezes. Over days, the ice builds into a dam, and the water backs up behind it. It finds its way under shingles and eventually into your dining room ceiling. The whole job of these roof pucks is to cut a path through that dam so water can escape. It's not a magical fix, but it's the fastest way to stop water intrusion when you've got a full dam formed.
How to Choose an Ice Dam Melter
Not all melters are roof-safe. Rock salt and sodium chloride will corrode your shingles, gutters, and landscaping. You want a product made specifically for roofs, usually calcium chloride or a blend with magnesium chloride. Look for brands like Roof Melt, Ice Dam Melters, or the generic calcium chloride pucks at Menards. A 10-pound bag runs $15 to $25, which covers about 20 to 30 applications. Avoid anything labeled "deicer for driveways" unless it says roof-safe on the bag. I've been on roofs in Edina where a homeowner threw down sidewalk salt and ended up with rusted flashing. Spend the extra few bucks on a real ice dam melter.
How to Use an Ice Dam Melter Safely
You don't need to melt the whole roof. The goal is to cut vertical channels so trapped water can escape. First, take a roof rake and clear the snow from the lower 6 feet of the roof. This gives the melter exposed ice to work on. Then, from the ground or a ladder, toss a puck or two about 2 feet up from the eave, spaced 4 to 6 feet apart. The calcium chloride will bore a hole down through the ice. Wait 30 to 60 minutes, and you should see water dripping off the edge. If you're on a ladder, keep three points of contact and never overreach. If your roof has a steep pitch, call a pro. A $50 service call beats a hospital trip. And don't put the melter on top of snow before clearing it — it needs direct contact with the ice to work.
When an Ice Dam Melter Isn't Enough
Here's the part most contractors won't tell you: these pucks treat the symptom, not the cause. If you've got ice dams every winter, you're losing heat through your attic. The real fix involves sealing air leaks around recessed lights, adding attic insulation, and making sure soffit vents aren't blocked. I did a full attic air-seal on a house in Richfield in 2016, and the owners haven't touched a roof puck since. That said, these pucks are a smart stopgap while you plan the bigger project. Keep a bag on hand for a sudden cold snap. I've seen a $20 melter save a $4,000 interior repaint.
Cost and Brands Worth Your Money
Calcium chloride pucks are the cheapest, around $1 to $2 per puck. Brand-name roof melt tablets like Roof Melt cost a bit more but dissolve faster in sub-zero temps. A 20-pound bag of generic calcium chloride pellets runs about $20 and lasts the average homeowner a couple seasons. Some people ask about heat cables — the electric wire that zigzags along the roof edge. Those work, but they're a permanent install and need to be up before the first snow. If you already have ice dams, an ice dam melter is quicker and cheaper.
My Honest Take on Ice Dam Melters
I've installed plenty of roof systems over 14 years, and I still keep a bag of pucks in my garage. They're the fastest way to open a drainage path when you're staring at a 2-foot icicle. But don't mistake them for a cure. Use them this winter, then put attic sealing on your spring list. And for the love of your shingles, never use rock salt on your roof. If you're not comfortable getting on a ladder, call a local contractor who does ice dam removal. That's not failure — that's wisdom. I've been on that roof. Let me save you the trip.
Stay warm. Stay dry. — Dean
No notes on this sheet yet.