Heated Gutters & Heat Cable Installation

Before you book

Choosing a heated gutter system: heat cable or heat tape

Most gutter heating uses one of two cable types. Constant-wattage cable puts out the same heat along its whole length whenever it is switched on. It is cheaper to buy but can overheat where it crosses itself or lies under leaves, and it wastes power on stretches that are already clear. Self-regulating cable has a conductive core that produces more heat where it is cold and less where it is warm. It costs more, but it can touch or cross itself safely and uses power where it is needed, which is why most contractors prefer it for gutters and downspouts.

The cheap plug-in heat tape sold for water pipes is a different product. It is not designed for gutters, ultraviolet light or standing water, and it should not be used on a roof.

Fully heated gutter systems also exist, where a heating element is built into a gutter guard or panel that sits on the gutter. These spread heat across the top of the gutter instead of along one line, and they look tidier from the street than cable. They cost more and are usually fitted as part of a new gutter or guard installation.

Where gutter heat cable goes

The cable must run all the way to where water leaves the system. Heating the gutter but not the downspout just moves the ice plug lower down, so the cable is normally run down the inside of each downspout to the outlet, and on buried drains, a short way into the drain line. In long gutters, one run of cable along the bottom of the trough is usually enough; in wide or deep gutters, or where ice builds heavily, a second run may be needed.

On the roof edge above the gutter, cable is sometimes laid in a zig-zag pattern over the first few feet of shingles, held with clips, to keep a path open for meltwater to reach the gutter. Whether this is needed depends on how far up the roof ice forms. On metal roofs, special clamps attach to the seams instead of clips under the shingles.

Power, circuits and controls

Every gutter heating system needs an outdoor circuit with ground-fault protection, because the cable sits in water. Larger systems need their own dedicated circuit sized for the total cable length. The connection point, usually an outdoor box near the eave, must be weatherproof. This electrical work should be done by a licensed electrician, and in many areas it needs a permit.

Controls make the difference between a system that costs a little to run and one that costs a lot. A simple switch inside the house relies on someone remembering to turn it on and off. A thermostat turns it on below a set temperature. A snow and moisture sensor turns it on only when it is both cold and wet, which is when ice can actually form, and is the most efficient choice for larger systems.

Running costs

Heat cable is rated in watts per foot. The running cost is the cable's total wattage, multiplied by the hours it runs, multiplied by your electricity rate. A long system left on all winter can add a noticeable amount to the electric bill, while the same system on a moisture sensor may run only on the days snow is melting. Ask the installer for the total wattage so you can estimate the cost for your own rates.

Heat cable is not a cure for a cold roof problem

Ice forms at the eave because the roof above the living space is warmer than the overhang. Heat cable manages the symptom by keeping drainage open. The cause, warm air leaking into the attic and heating the roof deck, is fixed with air sealing, insulation and ventilation. Where ice is severe, the best results come from doing both: improving the attic and heating the gutters and downspouts as a backup during the worst weather.

Snow guards on the roof above the gutter

On metal roofs, and on steep shingle roofs in heavy snow areas, snow can slide off in one large sheet and tear gutters off the fascia. Snow guards, small brackets or rails fixed to the roof a short distance above the eave, hold the snow in place so it melts gradually instead. They are often fitted alongside gutter heating, because both deal with the same problem from different sides.

Maintaining a heated system

Before each winter, check that the cable is still clipped in place, the jacket is not cut or worn where it passes over the gutter edge or into a downspout, and the gutters are clear of leaves. Debris lying on cable traps heat and, with constant-wattage cable, can overheat. Test the system on a cold day early in the season, and test the ground-fault protection as the manufacturer recommends.

Rain gutter heat cable, heat tape and heat trace

Rain gutter heat cable, rain gutter heat tape and rain gutter heat trace are three names for the same family of products. Heat trace for gutters is the trade name for self-regulating cable that increases its output as it gets colder. Gutter deicing cable runs inside the gutter and down the downspout, with a zigzag on the roof edge above. Ice melt gutter cables of this kind keep a path open for meltwater rather than melting all the snow.

Heated rain gutters are ordinary gutters with cable fitted. Gutter deicing works best when the cable is installed before the first freeze and on its own GFCI-protected circuit.