How to Install Heat Cable on Your Roof: A Comprehensive Guide
Understanding Heat Cables and Ice Dams
Ice dams occur when snow and ice on a roof melt due to the home’s interior heat. As this melted water flows down the roof, it refreezes at the colder eaves, forming a dam-like barrier. This can cause water to back up under the shingles and leak into the home, potentially leading to significant damage.
Heat cables are designed to prevent ice dams by warming the roof and gutters, preventing snow and ice from freezing. They are typically installed along the edge of the roof near the eaves and in gutters and downspouts.
Types of Heat Cables
There are two main types of heat cables:
- Constant wattage cable: Generates the same amount of heat regardless of outside temperatures.
- Self-regulating heat cable: Adjusts its heat output based on the temperature of the surface it is touching.
Self-regulating heat cables are typically recommended for roofs, as they are more energy-efficient and less likely to overheat.
Choosing the Right Heat Cable
The length of heat cable you need will depend on the length of your roofline, the depth of the eave overhang, and the length of any downspouts. It is important to choose a UL-listed heat cable, which indicates that it has been tested and meets safety standards.
Safety Considerations
- Always use a GFCI (ground-fault circuit interrupter) receptacle when plugging in heat cables.
- Do not use extension cords with heat cables.
- Inspect heat cables regularly for any damage or deterioration.
- If you are uncomfortable working on a ladder or at heights, consider hiring a professional to install heat cables.
Installation Instructions
- Measure for cable: Determine the length of heat cable needed based on the roofline length, eave overhang depth, and downspout length.
- Begin routing cable: Route the cable from the electrical outlet to the starting point on the roof, securing it with clips.
- Create the first loop: Form a loop at the bottom of the gutter and secure it with a clip.
- Continue the zig-zag: Run the cable back up the roof in a zig-zag pattern, creating triangular shapes about 15 inches wide. Secure the cable with clips at the top of each triangle.
- Run cable through gutters and downspouts: Lay the cable in the gutters and downspouts, securing it with hangers or S-hooks as needed.
- Complete the installation: Plug the cable into the GFCI outlet and ensure it is working properly. Leave the cable unplugged until snow or ice accumulates.
When to Call a Professional
- If you are uncomfortable working on a ladder or at heights.
- If you have a large or complex roof.
- If you are installing heat cables with new gutters or roofing.
Frequently Asked Questions
How much does it cost to run roof heat cable?
Typical heat cable uses about six to nine watts per foot per hour, so a constant wattage cable that’s about 100 feet long running for 24 hours a day for one month would cost about $40 to $60 in additional energy costs.
Should you leave heat cable plugged in?
Roof heating cables should only be left on overnight when the temperatures are lower than 40°F or in icy conditions. Avoid leaving heat cables plugged in 24 hours a day, although you can if you’re hit with a big winter storm.
How long does heat cable usually last?
Heat cable typically lasts about three to five years; the more you use it, the shorter its lifespan.