As we all know, accumulation of snow has significant impacts on how a home’s roof performs (or doesn’t) over the course of a winter. Unattended ice dams can quickly cause
leaks and costly repairs. Materials, pitch, drainage paths and orientation are important factors in how the roof will perform but these same parameters may be limited by the desired aesthetic design. Insulation and venting strategies (e.g., hot vs. cold roof design) must also be considered in any design for this region but, in the end, the use of heat tape, protected panel systems, snow fences and/or clips, and general snow removal maintenance may have to be incorporated. In this article, we will review these items’ applications, benefits, drawbacks, operating costs, and reliability as well as some best-practice design considerations.

• Heat tape is a must have for any application in which gutters and downspouts are employed. If installed properly, it will prevent gutters and downspouts from freezing. Note that in any heat tape application the water must be given a heated path to the ground. Therefore, even if there were no gutters prior to the installation of the heat tape, a gutter or similar system is required upon the installation of the heat tape.
• Heat tape is most often installed in a zig-zag pattern. This configuration allows water to pass through ice dams that form on roofline edges. It’s important to note that the heat cable itself needs to hang past the roof edge by 3/8″ to 1″ in order to allow water to pass. Runs should be planned to not exceed 250°.
• Heat tape can be run straight up valleys and downspouts and laid straight in gutters to assist with the passage of water.
• Heat tape can be retrofitted fairly easily as needed, which allows you to experience the affects of snowfall prior to incurring the expense of needless installation and operation (see Heat Tape Design below for tips on designing the power supply and drainage systems for future installation)

• If installed properly, heat tape greatly reduces the likelihood of having roof leaks caused by ice dams.
• Heat tape reduces the need for maintenance in the form of roof shoveling.
• Readily available, most roofing and gutter contractors will install the heat tape if provided a power supply. Current pricing is around $9 per lineal foot installed.

• The operating costs of heat tape can be significant. According to one leading manufacturer, when “in snow or ice” the cable output is approximately 8 watts/foot. Since the efficiency is near 100%, the input requirement is also approximately 8 watts/foot. So, if the 250′ maximum run of cable operates for an hour “in snow or ice”, it could use 2000 watts or 2kWh. Taking this further, if this cable runs 24 hours a day for a 31 day month, it will use 1480kWh. At $0.10/kWh (Colorado average as of April 2008), each cable could cost $148 per month to operate. It is probable that the cold temperatures of December through February will keep the cables running a significant portion of the time, so a client with 2 new cables could expect to experience an approximately $300/month higher electric bill.
• Heat tape circuits should remain on at all times. The tape is not designed to melt ice (which might form while the system is off) but, rather, to keep ice from forming. If ice builds on the tape while it is off, the tape may melt a small tunnel around the wire when turned back on but it may not be able to melt the bridge layer of ice above, potentially allowing the formation of an ice dam. A snow/moisture sensor can also be added to the system to allow operation only when snow is falling (though you have to be careful where you place the sensor).

• Most readily available heat tape is ’self-regulating’ meaning, as temperatures drop, more resistance occurs naturally in the cable, which then causes the cable to draw more power. Here’s the catch – if it is too cold, or if the tape becomes bound by ice, the resistance in the cable can reach levels which prevent the electric current from passing through it. When this happens, it usually shuts itself off or it may even trip the circuit’s breaker. At this point, one will likely have to clear the blockage, check the tape, and reset the breaker. Homeowners or caretakers must continuously monitor heat tape zones to ensure that they are working properly. If a heat tape circuit goes down, even for a short period of time, frozen gutters, downspouts, ice dams and roof leaks can occur in rapid succession.
• Heat tape is easily damaged or severed by snow shovels and ice picks. If a segment gets cut, or if the protective jacket of the cable gets nicked, the heat tape leg will likely trip its breaker and stop working. Maintenance workers must be carefully supervised, informed of all heat tape locations, and must check up after they have completed work to ensure that the heat tape is still working. While circuit splices are available, they should be minimized.
• The sun’s rays break down the cable’s protective coating over time. Depending on sun exposure, lifespan of the product can vary significantly.

• Heat tape requires a power source (120VDC or 240VDC), which should be designed into the structure even if the system is not installed initially. Typical outlet locations include soffits or, preferably, near the bottom of the downspout. The wire should enter the downspout through a grommet and should be protected in a conduit if the run from the wall to the downspout is significant.
• Heated gutter downspouts should empty directly into a subsurface drain and the heat tape should extend into the drain far enough to be below the frost line. Properly designed drainage systems and inlet locations can save significant money when retrofitting a heat tape system.
• Plan your heat tape lengths around the requirement that a maximum heat tape run is approximately 250′. Don’t forget to figure in the zig-zag pattern on roof edges and a path for the water to reach the ground (gutter/downspout/drain length).

• A number of companies have been working to develop solutions to some of the common problems previously reviewed – namely, the tendency for heat tape to become damaged during snow removal, snow slides, or by constant exposure to ultraviolet rays. While not explicitly endorsing any single company, it is helpful to know that a variety of different products exist which offer some improvement upon the admittedly vulnerable classic heat tape option. Options include heat cable installed in a protective channel system, bronze-mesh strips installed under the roofing shingles themselves, as well as other custom options. All have components that install on roof edges and valleys and can be tailored to fit most other needs but you need to be aware of the details.
• The most common system we’ve worked with installs continuous extruded aluminum track up to 10’ in length on the roof edges and valleys. The heat cable is then run inside channels in the track and a copper or colored aluminum cover is installed on top of it. Control systems monitor outside environmental conditions and ensure (in theory) that the heat tape system is operating in the conditions defined by the user.

• In our experience, the systems perform well and there have been no ice dam related roof leaks where the system was installed. The surface area of melting is much greater than that of the heat tape as the heat is distributed across the extruded track and cover. This heated surface will remain bare during the winter whereas heat tape only provides conduits for drainage immediately around the wire. The greater area of panel systems also moves the common freeze-thaw interface with the roof’s edge upward, closer to the wall/roof intersection, effectively reducing the width of the unconditioned overhang.
• The heat cable, once installed inside the track and safely encased in its protective cover, is more protected than its naked counterpart.
• The appearance of the system is cleaner than that of heat tape routed across the roof’s surface.

• Suppliers are still developing product interfaces for the multitude of applications that the system undoubtedly encounters. For example, in locations where two valleys meet at the ridge of the roof, the track and wire may need to run up one valley and then down the other. However, there exists a vulnerability of 3″ to 6″ across the ridge where the cable is not encased in metal as it transitions from one track segment to the next.
• The panel system still requires gutters and downspouts with the heat tape wire routed in the same fashion as heat tape only systems. At the ends of the panels, (installed along the eaves) the cable must transition from the panel cover into the gutter system to be connected. Some concern exists that at the panel edge, the cable could become cut or worn by its own weight pulling downwards against the end of the track.
• As mentioned above, one the possible problems one can encounter with heat tape is the possibility that the cable becomes ice-bound, or so cold that the current cannot pass through it, which then causes the cable to shut off. The panel systems we have used are not immune to this potential issue, and like more conventional heat tape, must be monitored to ensure they are continuing to operate correctly.
• The metal track and cover system mount onto the roof sheeting or protective underlayment. Due to its thickness of ˜3/4″, the standard system cannot be installed on roof pitches of 3:12 or less. There are product variations that can be mounted on lower pitches but we have not tested their performance.
• Panel systems are expensive to purchase and install, costing about three times that of standard heat tape at $25 per lineal foot installed. When performing the cost benefit analysis for this option, additional factors to weigh include: installer selection (some but not all roofing contractors are familiar with this type of product), coordination costs associated with the multi-sub-contractor (roofing and electrician) installation, the decreased expense of replacing snow slide, chopped or UV damaged heat tape, and the decreased expense of manual snow removal.
• Operating costs can rise above those of classic heat tape as the energy output during full operation ranges from 24 to 36 watts per lineal foot. While the zig-zag pattern of heat tape is not used, the panels do require 2-3 parallel runs of heat tape per lineal foot.

• The systems have not been operating for great periods of time but given the fact that the wire is a variation of (or even identical to) classic heat tape, we have no reason to doubt its long-term operation.
• It should be noted that these systems often require more sensors and controllers than on a standard heat tape application. While all are currently operating without an issue, none have undergone a significant test of time.

• When designing for panel systems, be aware of the same issues discussed for standard heat tape above – power supply, drainage paths, and length requirements
• Locations for additional sensors and controls may need to be defined. This may be especially true in situations where the roof experiences significantly different environments (e.g., a sunny side and a shady side) as you will want to route separate circuits such that each one operates within a specific environment. The circuit’s controlling sensor should also be placed within this environment to improve the circuit’s control and performance.
• You may want to keep every edge of the roof aesthetically consistent so you may need to plan for installing additional track and covers in areas where the heat tape cable is not even present.
• Note that the heat tape wire may show at transition panel points as it exits and enters from the ends of the track components. Adding panels to details such as cornice returns can be done but it is important to understand the look of the final product, including the routing of the wire if snow melting these areas is required.

• Snow slides injure and kill people each year, and at the very least, cause costly damage to roofing and gutter systems. There are options available to control snow slides, including many styles of snow fencing and roof clips. While snow fences are designed to retain the snow on the roof, roof clips are designed to break up the sheet of snow so that smaller portions break off over a longer period of time. Well designed clip systems require higher snow sheets to pass over the lower clips which act to break up the sheet’s mass.
• Snow fences and snow clips should be secured to the roof in a robust way. Should sliding snow or severe icing conditions loosen a snow fence or clip, the repairs need to be conducted very carefully and thoroughly as most are well bonded to the roof through numerous penetrations.

• Often times the best aid for roof performance is to have a professional maintenance person clear the snow and ice the old fashioned way: with a shovel. It is strongly advised that the shovels by plastic to limit damage. The snow should be removed periodically based on the pitch of the roof and snow load capacity of the structure. Remember that thawing and refreezing snow in the spring can increase its weight significantly.
• An alternative to the shovel that can often be better for the roof’s longevity is to use one of the new high-powered but light snow throwers. In the right hands, and especially if used right after large snows, the snow thrower vastly limits the hammering and chipping associated with shoveling.
• Make sure the maintenance crew is aware of all heat tape, snow fence and snow clip locations.