1. Layout
The size and shape of your roof will factor prominently in choosing the area where you need to put your heat cable. A good rule of thumb is to place the heat cable on any portion of the roof or gutter system susceptible to snow or ice build-up. The common areas of concern on a roof are:
Roof Overhangs (with or without a gutter system)
Roof Valleys
Roof Eaves
Gutters and Downspouts
Drains and Scuppers (on a flat roof)
2. Amount of Cable
Calculating the amount of cable required for your specific roof will tell you how much heat cable to purchase. You will need to calculate the entire length of your roof, the length from the gables to the valley points, your downspout and drain, and the depth of your soffit.
To help in the calculation process, you can go to Drexan's website or watch one of these videos from, Wasatch Heat Cable.
3. Electrical Requirements and Cable Components
It is crucial to have a proper power source that meets the needed electrical requirements to ensure that your heat cable runs safely and effectively. The length of cable you need for your roof plus the suggested start-up temperature will help determine your specific electrical needs.
Depending on your home's current power source options and the type of heat cable you choose, you may have to install a new breaker or outlet as a dedicated power source for your heat cable system.
Self-regulating heat cable systems like Drexan are considered heavy electrical equipment and, therefore, by code, require that you use Ground Fault Equipment Protection (GFEP). If you choose instead to buy constant wattage cable, you only need the support of a standard ground fault circuit interrupter (GFCI). For more information on why we consider self-regulating heating cable superior to constant wattage, you can go to our previous blog post on the advantages of self-regulating cable.
Besides the cable itself and its power connection, other components you typically find in a heat cable system include a splice kit, end seal kit, and junction box. Since electrical projects often prove challenging and hazardous, we strongly suggest you consult with a professional electrician for this step.
4. Installation
Now that you have done most of the prep work, your next step is to install your heat cable system. Properly installing your heat cable will ensure that your system works effectively to prevent ice and snow build-up on your roof and protect against circuit breaker trips and possible fires.
Some things to keep in mind during installation:
The heat cable system needs to be in contact with the roof and gutter systems. Do not install heat cables underneath any roofing materials.
Do not use nails, screws, or staples to attach the heat cable. This can damage the line, but, more importantly, it can damage the roof. Holes in your roof will allow water to get in and possibly damage your home's interior spaces. The best option is to use roof clips and adhesive to secure the cable.
Considering a snow retention system may help prevent damage to the cable as snow slides down the roof.
If your roof does not have a gutter system, you'll need to extend drip loops past the roof edge for your heat cable system.
If multiple circuits are necessary for your system, it is best to place all junction boxes in one area to reduce the number of power feed conduits.
Place junction boxes under a covered area, such as a roof overhang, to protect against direct exposure to the elements. You will need to install drip loops where the cable and junction box meet.
You should place your heat cable 12' down the roof drain into the warmer part of the building.
You'll need to place the heat cable down below the frost line for downspouts that lead to underground sewers.
If ice dams are not a concern and you have not experienced them on your roof, limiting your heat cable system to the gutters and downspouts may be sufficient.
5. Controls
You can choose from three recommended control methods for your roof and gutter heat cable systems.
Manual - Switches on the heat cable manually.
Ambient - Uses an ambient thermostat to sense the outside temperature. When the temperature dips below freezing, the cable becomes energized.
Automatic - Keeps roofs and gutters free from snow and ice while conserving energy. The cable connected to an automatic control is only energized when low temperature and moisture are present.
Installing a Drexan heat cable system yourself is possible, and as long as you follow specific guidelines, you can have a roof heating application that will serve your needs for years to come. Summer is a great time to install heat cable, especially if you intend to do it yourself.
For questions or concerns as you prepare and install, you can check out Drexan.com or contact one of our professional installers at HeatCable.com.