Every winter, homeowners in Glenview and Northbrook call us about the same problem: water stains on a bedroom ceiling, icicles the size of baseball bats, and a thick ridge of ice along the gutters. Ice dams are one of the most common winter headaches in Chicagoland’s older Cape Cods, split-levels, and 1950s–1970s ranches. The good news is that they’re predictable and fixable. The key is understanding that an ice dam is a symptom, and the real cause is usually inside the house.
This guide explains what causes ice dams, when roof-edge heat cable is the right tool, how to install it safely on a dedicated electrical circuit, and what it costs in 2026.
What Causes Ice Dams?
An ice dam forms when the upper part of your roof is warm enough to melt snow, but the eaves (the overhang past your exterior walls) stay below freezing. Meltwater runs down, hits the cold eave, and refreezes. Over days, that ice builds into a ridge that traps more water behind it. That water backs up under shingles and leaks into your attic, walls, and ceilings.
The warm roof deck almost always comes from heat escaping the living space:
- Air leaks around recessed lights, attic hatches, plumbing stacks, and top plates
- Thin or settled attic insulation
- Poor attic ventilation (blocked soffits, no ridge vent)
- Ductwork or a furnace in the attic or knee walls leaking warm air
- Bath fans venting into the attic instead of outdoors
Fix the Cause First, Then Consider Heat Cable
We’re an HVAC and electrical contractor, so we can see both sides of the problem. Our honest recommendation: if the attic has obvious air leaks, leaky ducts, or bath fans dumping into it, fix those first. They cost you money all winter and can cause mold, not just ice dams.
That said, some roofs will form ice dams even after reasonable air sealing: low-slope sections, valleys, north-facing eaves, dormers, and areas above cathedral ceilings or knee walls where you simply can’t add much insulation. For those spots, heat cable is a practical, targeted solution.
| Fix | What It Solves | Typical 2026 Cost |
|---|---|---|
| Attic air sealing | Warm air reaching the roof deck | $800–$2,500 |
| Added attic insulation | Heat loss through ceiling | $1,500–$4,000 |
| Sealing/insulating attic ductwork | Duct heat melting snow | $600–$2,000 |
| Rerouting bath fan to exterior | Moisture and heat in attic | $350–$900 per fan |
| Roof-edge heat cable (installed, with circuit) | Problem eaves, valleys, gutters | $900–$3,500 |
Types of Roof and Gutter Heat Cable
Constant-wattage cable
The inexpensive zig-zag cable sold at big-box stores. It puts out the same heat no matter what, can’t overlap itself, and tends to run all winter if nobody turns it off. It works, but it’s the least efficient and has a shorter lifespan.
Self-regulating cable
This is what we recommend. Self-regulating cable increases output as it gets colder and reduces output as it warms, so it’s safer and uses less energy. It can be cut to length on site and handles gutters and downspouts well.
Panel or clip-in systems
Premium aluminum panel systems mount along the eave and hide the cable. They look cleaner and melt more evenly, but cost significantly more. Popular on high-visibility front elevations.
Why Heat Cable Needs a Proper Electrical Installation
Many DIY heat cables are plugged into an exterior outlet with an extension cord. That’s where problems start. A proper installation includes:
- A dedicated circuit sized to the cable’s total load. Self-regulating cable can draw high inrush current on a cold start, so circuit sizing matters.
- Ground-fault equipment protection, required by the National Electrical Code for fixed outdoor de-icing equipment (typically a 30mA equipment protection device).
- Weatherproof connections and junction boxes rated for outdoor use.
- Controls so the system only runs when it’s needed.
If your panel is full or older, we’ll check whether it can accept another circuit. Learn more about our circuit and wiring services.
Control options
| Control | How It Works | Energy Use |
|---|---|---|
| Manual switch | You turn it on and off | High if forgotten |
| Ambient thermostat | Runs when outdoor temp is in a set range (e.g., 15–38°F) | Moderate |
| Snow/moisture sensor controller | Runs only when it’s cold AND wet | Lowest |
| Smart relay / Wi-Fi | Remote control, scheduling, usage tracking | Low (with sensors) |
What Heat Cable Costs to Run
Self-regulating cable typically draws around 5–8 watts per foot in cold conditions. A 100-foot run at 6 W/ft is about 0.6 kW. Running 8 hours a day for 60 days is roughly 290 kWh, or around $45 for the season at typical ComEd residential rates. A sensor controller keeps it well below that; leaving a cable on all winter can cost several hundred dollars.
Where to Put It
- In a zig-zag or straight run along the eave, extending over the exterior wall line
- Inside gutters and down through downspouts so meltwater has a path off the roof
- Along valleys and around dormers where snow collects
Heat cable without a clear drainage path just moves the ice dam. Downspouts that freeze solid are a common reason DIY installs fail.
Glenview & Northbrook Homes We See It On Most
In Glenview, 1.5-story Cape Cods with knee-wall bedrooms are classic ice dam houses because the sloped ceiling sections are hard to insulate. In Northbrook, we see it on split-levels with low-slope roof sections and on homes where a furnace or ducts were installed in the attic. For those homes, fixing ductwork and ventilation and adding targeted heat cable is usually the most cost-effective combination.
Financing Available
Whether you need air sealing, duct repair, a new circuit, or a full heat cable system, we offer financing through Sunbit and PowerPay.
A Simple Fall Plan for Ice-Dam-Prone Homes
If your home had ice dams last winter, here is the order we recommend tackling it. First, have the attic inspected for air leaks, duct leaks, bath fan terminations, and blocked soffit vents. Second, fix the cheapest high-impact items: seal around recessed lights, the attic hatch, and plumbing and wiring penetrations, then route any bath fans outdoors. Third, top up insulation where it is thin. Finally, add self-regulating heat cable only at the eaves, valleys, and gutters that are still likely to dam. This approach usually costs less than a whole-roof cable system, lowers your heating bill, and protects the roof where it matters most.
Frequently Asked Questions
Will heat cable damage my shingles?
Not when installed with proper clips designed for your roofing material. We avoid nails through shingles and follow manufacturer instructions.
Can I install heat cable myself?
You can hang the cable, but the circuit, ground-fault protection, and outdoor connections should be done by a licensed electrician. Extension-cord setups are a fire and shock risk.
Should I remove ice dams with a hammer or salt?
No. Chipping damages shingles and gutters, and rock salt can harm roofing and landscaping. A roof rake to remove snow from the first few feet of roof is the safest short-term step.
When should I install heat cable?
Fall is ideal. Once snow and ice are on the roof, installation is harder and less safe.
Does heat cable replace insulation?
No. It’s a targeted fix for problem areas. Air sealing and insulation reduce your heating bills; heat cable does not.
Schedule Before the First Snow
MMDS helps homeowners in Glenview, Northbrook, and the North Shore solve ice dams from the inside out. Call (847) 221-6280 or request an estimate online.