How To Install Heat Cable On Metal Roof


Heat cables, roof de-icing cables are wires encased in special rubber insulation and covered with aluminum foil. They provide an electrical path to the roof, allowing snow and ice to slide off without damaging it. Heat cables are installed on roofs before the arrival of winter, so they are ready for use when needed. Heat cable can be mounted by staples, nails, or screws directly on top of asphalt roofing shingles using self-tapping screws or cable clips.

How to Install Heat Cable On Metal Roof

Please note mounting height is very important depending on your geographical location. The higher you install them, the more effective they will be, but they must not touch any metal objects, including gutters, etc., because this may cause damage due to the high voltage that runs through them. In this article, I will discuss how to install heat cable on metal roof properly. So let us get into the core discussion.

Stepwise Guide on How To Install Heat Cable On Metal Roof

  1. Planning how to install heat cables on metal roofs is the first thing you should do before installing heating cables of any type. First, decide which areas of your home are coldest and where you want the heating cable to be installed, and this will give you a better idea as to how much heat cable you might need for each area.
  2. Once planning is complete, and it’s time to begin installing Heat Cable On Metal Roof: First, lay out all sections, cuts, and rolls in sequence so that they’re ready for installation when you need them. Each roll comes labeled as to what part number it is, i.e.… P-05 etc.… Layouts always start by unrolling perpendicular across the longest side or straight down one of the longest sides of a roof so that the roll doesn’t have to be unrolled over obstacles. We suggest you begin in one corner or an area with very little headroom, so you don’t end up crawling around on your knees.
  3. Heat Cable On Metal Roof installation: Always do all inside wiring before covering with tape and insulation. This will keep heat loss from wires to a minimum; even though heat cables are insulated, they still lose about 5% of their heat through the wire strands that connect them at each end. The more connections, the greater this loss becomes.
  4. First, attach the cables using adhesive-lined cable clamps for permanent installations or self-tapping screws for temporary installations onto framing members until the entire surface area is covered. It’s essential to have an electrician in your home or in your local area to help you with the wiring of heat cable on the metal roof.
  5. Once the cables are installed, they must be insulated, covering all exposed surfaces with spray-in polyurethane foam insulation. The self-regulating heating cable can also be used that comes factory insulated, which eliminates this step.
  6. Now it’s time to install tape over cables, ensuring no foam insulation can get inside the outer protective jacket of wires.  The video should overlap and cover all exposed wires and clamp heads.
Installing the Heat Cable on Metal Roof

Precautions While Installing Heat Cables on Metal Roof:

  1. If the metal is freezing, it can cause the heating cable to freeze and break. Therefore, do not install on metal roofing in temperatures below 40 degrees F.
  2. For small areas, use 6″ heat cables. For larger sizes, use 10″ or 12″ heat cables.
  3. Make sure you cut the proper size hole for your heat cable, usually about 1-1/2″. You can also buy split collars that go around the pipe to help keep water out of the line if it leaks through the holes when installed on a calm day when condensation may occur in the base pipe. A good quality self sealing silicone caulk will work fine if they are correctly installed using screws or nails with washers or pins with rubber washers.
  4. Make sure the cables are not lying against each other and touching any metal parts of the roof or walls that will not be warm enough to heat the clamps causing them to freeze and break off; this is a widespread problem experienced by people who have done this work themselves without experience in heat cables so call a professional if you need help. Also, do not install on calm days when condensation can form on cold metal roofs or pipes, which can cause leaks through your heating cable holes, causing water damage.
  5. Heat cables should run continuously from end to end and should never be installed diagonally (the safest way). Still, they can be installed at any angle as long as there is a one-foot gap between each cable.
  6. Never allow the cables to run in any direction through metal flashing or wall vent openings. You can usually put a gap in your wall vents for heat cables, but it is unnecessary; just remember where your heat cables are so you don’t cover them up with insulation when insulating your walls during the winter months. If there are areas of roofing that need to be covered with additional insulation over the top of the heating cable, use low voltage to keep from heating the shingles and causing damage due to high temperatures so call an expert if you have questions about installing heat cables on metal roofs correctly yourself without experience.

Frequently Asked Questions

How Do Heat Cables Work?

They rely on the principles of convection, conduction, and radiation (a form of the infrared heater) to transfer heat to metal roof decks. First, the hot air rises through the cavity between the j-heats and the metal decking, transferring its heat by convection, which heats the roof deck.

Heat  Cables  Working

Then heated air escapes through any pre-existing vent holes at gable ends etc., and this is aided by warm air rising naturally because it’s lighter than cold air. This causes a low-pressure area at the top of the roof, and any pre-existing vent holes will suck warm air out, relieving the low pressure. Finally, the heated air also transfers heat to the metal decking (radiation) and even conducts distance (conduction).

What is R-Value For Heat Cables?

R-value is the term used to describe thermal resistance. It refers to how good an insulator material is. The higher the value, the better it resists heat flow and the better job keeping you warm in winter and cool in summer. R-value also becomes essential when you are looking for insulation for underfloor heating, as this step determines which cable and cable spacing (the required minimum distance between cables) will be needed:

The recommended minimum R-value of floor insulation varies according to room type but generally falls into 1 of 2 categories:

  • R-Value 3 or more = Warm floors where the building structure has been designed such that there is no cold bridge (defined as any point through which heat energy can transfer from a warmer to a colder space, such as the gap between the ceiling and floor above).
  • R-Value less than 3 = Cold floors where there is likely to be a cold bridge.

Generally, when installing underfloor heating in new buildings or an extensive remodel of an existing building with all new insulation, you will find that the thermal resistance of your floor insulation meets the higher standard. In these situations, heat cable can be run in any pattern with no spacing required because there is no danger of creating a cold bridge.


I hope you have obtained a clear overview of how to install heat cable on metal roof. Ensure all the precautions are correct. Thank you and have a nice day!

You may also read – How to clean a metal roof from the ground.

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