How to Install Heat Cable on Your Roof

Installing heat cable on your roof is an effective way to prevent ice dams and icicles from forming during winter. Heat cable, also known as heat tape or de-icing cable, runs along the roof’s edge and works to melt snow and ice as it accumulates. Properly installing heat cable takes some time and effort, but it can save you from expensive roof repairs and dangerous falling ice in the long run. Here is a comprehensive guide on how to install heat cable on your roof.

Choose the Right Heat Cable

There are a few types of heat cable to choose from:

Self-Regulating Heat Cable

This type of heat cable adjusts its power output based on the temperature. It provides more heat when needed but conserves energy when not needed. Self-regulating cable is convenient because it maintains a steady temperature of around 40°F to melt ice and snow but won’t overheat your roof. It’s the safest and most energy efficient option.

Constant Wattage Heat Cable

Constant wattage heat cable provides a continuous level of heat. It’s not temperature regulated, so it will continue heating even after the ice and snow have melted. Constant wattage cable requires more monitoring to avoid overheating and energy waste.

Mineral Insulated Heat Cable

This type of cable has a metal sheath around the heating element to conduct and radiate heat. It’s very durable and energy efficient. Mineral insulated cable is more expensive than other options but lasts longer.

When choosing heat cable, pick a self-regulating or mineral insulated cable rated for outdoor use. The cable should be properly sized for your roof length. It’s better to have extra cable than to cut a cable short. Opt for cable with UL or CSA ratings from reputable brands.

Gather the Right Supplies

In addition to the heat cable itself, you’ll need the following supplies and tools:

Weatherproof cable ties or clips to secure the cable
Roof sealant that’s compatible with the heat cable
Corrosion resistant screws, washers, and clamps for securing the cable
A fiberglass mounting strip to attach the cable to metal roofs
An electrical connection kit for splicing the cable
A thermal switch or thermostat to control the cable
A voltage meter and wire cutters
A ladder, scaffolding, or rooftop safety equipment

Make sure to use only weatherproof electrical supplies rated for outdoor use. Avoid tape which can deteriorate over time.

Calculate the Cable Layout

Before going up on the roof, calculate the amount of heat cable needed and map out the installation layout:

Measure the linear footage around the roof’s edge where heat cable will be installed.
Add an extra 10% to allow for mistakes and alterations.
Follow the manufacturer’s instructions for maximum run length per circuit.
Sketch a layout for where the cable routes and how it will be spliced.
Mark where you’ll place the cable ties, sealant, and clips for securing it.

Careful planning and measurements will ensure you install the right amount of cable in the optimal layout.

Prepare the Roof

Proper prep work is crucial for heat cable installation:

Remove any debris, leaves, or old roofing sealant from installation areas.
Repair any damaged shingles, bent flashing, or leaky spots along the roof.
Install drip edge and gutter guards if missing. This helps divert water away from the cable.
Seal any open electrical, plumbing, or gas lines that go through the roof.
Use roof sealant to fill in cracks, seams, and holes under where the cable will run.

Preparing the roof prevents leaks and damage that could compromise the cable.

Mount the Thermal Switch or Thermostat

The thermal switch controls the heat cable automatically based on the temperature. Mount it in an accessible location outside where it will accurately read the outdoor temperature. Follow manufacturer instructions for wiring it to the heat cable circuit.

Alternatively, you can use a programmable roof de-icing thermostat mounted in your attic/loft space. It allows manually adjusting the activation temperature as needed.

Run the Cable Along the Roof

Starting at the power connection point, begin running the heat cable:

Use cable ties to loosely secure the cable about every 12 inches along the roof. Don’t cinch ties tight yet.
Run the cable along the entire roof edge, making 90° bends around corners.
Avoid running cable diagonally across the roof. Stick to the perimeter edge.
Leave extra slack in the cable instead of pulling it taut around bends.
Use clips or sealant to secure the cable to metal roofs. Extra care is needed.
Make watertight connections when splicing multiple cables following the manufacturer’s instructions.

Go slowly to avoid kinks, tears, or gaps. The cable should follow the roofline neatly.

Connect and Seal the Cable

Once cable is run, waterproof the connections:

Connect the cable strands to the power source and thermal switch/thermostat.
Use a multimeter to check for continuity. Fix any faulty connections.
Firmly tighten the cable ties once the layout is verified.
Apply roof sealant over the entire cable length using at least a 1/4 inch thick layer.
Use extra sealant around splices, connectors, and tie downs. Seal thoroughly.
Avoid using too much sealant that could pool and lift the cable. A thin, uniform coating is best.

Sealing and weatherproofing the cable properly prevents damage from water infiltration.

Test Operation

Verify proper installation before winter hits:

Turn on the power and thermal switch so the cable starts heating up.
Use an infrared thermometer gun to check the cable temperature along its length.
There should be consistent, even heating without any cold spots.
Adjust ties, connections, or sealant if any section is not heating right.
Turn the cable on/off repeatedly to confirm automatic controls work properly.

Testing the heat cable right after installation provides peace of mind that it will operate effectively when needed.

Perform Regular Maintenance

To keep your roof heat cable working safely for years:

Visually inspect the cable in spring for any damage after winter ice melts. Look for cuts, excessive brittleness, or gaps in the sealant.
Repair any problem spots found by resealing or replacing damaged sections of cable.
Remove leaves, debris, and branches from around the cable before winter. Prevent buildup of snow/ice on the cable.
Periodically check that cable ties are snug and not broken. Replace deteriorated ties.
Confirm the thermal switch still works properly by testing cable heating in fall.

With routine seasonal maintenance, roof heat cable can provide many years of reliable ice melting action.

Safety Precautions

Comply with these safety measures when installing roof heat cable:

Turn off electricity when doing any work on the cable to avoid shock hazard.
Use extreme caution when working on ladder, scaffolding, or roof to prevent falls.
Wear electrical gloves and use insulated tools when handling cable. Avoid contact with skin.
Keep air intake vents clear to prevent fire risk from overheating cable.
Place “Heat Cable Installed” signs by electrical panels and roof access points as a reminder.

Following basic electrical and rooftop safety procedures prevents accidents with heat cable.

Troubleshooting Common Issues

Refer to this troubleshooting guide if your roof heat cable encounters problems:

Cable Not Heating At All

Check for tripped breaker or thermal switch off position.
Inspect all connections for loose wires or moisture corrosion.
Test for continuity and voltage to isolate breaks in the cable.
Replace damaged sections or splice in new cable as needed.

Partial Cable Heating

Check for damaged sections not heating up using a thermometer gun.
Remove sealant to inspect the underlying cable for punctures or cuts.
Splice in new cable at damaged locations after sealing any roof breaches.

Ice Not Melting Effectively

Ensure cable was installed fully around all roof edges and valleys.
Increase thermal switch activation temperature if set too low.
Upgrade to a higher wattage heat cable if needed for large/complex roofs.

Cable Overheating

Lower control thermostat to proper temperature setting.
Check for damaged cable still heating even when switched off.
Reduce long cable runs by adding circuits to avoid overloading.

Heat Cable Alternatives

While heat cable is the most convenient and effective de-icing option, here are a few other ways to protect your roof:

Heated Roof Panels

Heated panels contain integrated heating elements to melt snow. They are very effective but involve replacing your entire roof.

Heated Roof Shingles

Similar to heated panels, electric heating coils are built into durable composite shingles. This option also requires reroofing but is easier to retrofit.

Manual Removal

Using rakes and other manual tools to clear snow buildup before it melts and refreezes into ice dams. Very labor intensive!

Improved Insulation and Ventilation

Adding extra insulation in the attic and improving airflow can help reduce how much snow/ice accumulates. Not a complete solution.

For most homes and budgets, installing heat cable is the best way to safely and effectively prevent roof ice dams and icicle buildup. With the right materials and proper installation technique, roof heat cable can spare you from the damage caused by ice dams for many years. Be sure to take the necessary safety precautions and test the cable each season. While a bit of effort to set up initially, roof heat cable will repay the time and expense many times over by protecting your roof, gutters, and landscaping for winters to come.

Frequently Asked Questions About Installing Roof Heat Cable

How much heat cable do I need for my roof?

The amount of heat cable needed depends on the linear footage of your roof edge that requires de-icing. Calculate your total roof edge distance and add about 10% extra cable for mistakes and alterations during installation. Follow the cable manufacturer’s guidelines for maximum run lengths.

Where should I install the cable on my roof?

Install heat cable along the entire lower edge of the roof and in valleys where ice dams are prone to forming. Prioritize areas where meltwater tends to pool and freeze overhangs. Don’t run cable diagonally across shingles.

Should I seal over the entire cable length?

Yes, sealing the full length of the cable with a thick layer of roof sealant designed for heat cables is highly recommended. This prevents moisture damage at the connections. Avoid using too much sealant near the edges where it could pool under the cable.

What temperature should I set the thermal switch at?

The control switch should be set to activate the heat cable at around 35-40°F. This temperature is warm enough to melt ice but cool enough that the cable won’t run constantly. Adjust as needed based on local climate and how quickly your roof accumulates ice.

How do I get power to my roof heat cable?

Running the power cord through your attic/loft space is the easiest method. Hire an electrician to install and properly ground a dedicated outlet that can supply sufficient amperage for the total cable length. Always use GFCI circuits.

Is it safe to install heat cable myself?

Roofing work involves inherent dangers from falls and electrocution hazards. If you are experienced with both roofing repairs and electrical wiring, take the proper safety precautions when self-installing heat cable. Consider hiring a professional otherwise.

How long can I expect roof heat cable to last?

With proper installation and seasonal maintenance, heat cable typically lasts 15-20 years before needing full replacement. Inspect aged cable carefully each year and replace any visibly damaged sections as needed to extend its useful lifespan.

Can I turn on the heat cable manually if needed?

While automatic thermal switches are preferred for convenience, you can also control roof heat cable manually using a programmable thermostat mounted in the attic/loft space. This allows adjusting the activation temperature up or down whenever desired.

Conclusion

Installing heat cable is an efficient and cost-effective way to protect your roof, gutters, landscaping, and foundation from dangerous ice dams. Follow the steps outlined in this guide for safe DIY installation or hire a professional roofer for optimum results. With proper care and maintenance, roof heat cable will provide the peace of mind that comes from preventing thousands in potential water damage for many winters before needing to replace the system. Investing in heat cable now can prevent exponentially larger repair bills down the road. Keep your home safe from the ravages of ice dams and falling icicles this winter and you’ll reap savings for many seasons to come.