Winter’s icy problems are the furthest thing from our minds in the summer months. Don’t be a procrastinator: it’s the right time to read up on roof heat cables.
Proper ventilation and insulation is the key to a healthy roof, but if the roof is proving to be tricky in spite of good ventilation and insulation, look to roof heat cables to help prevent ice dams.
What is an ice dam?
Your roof is coldest at the edges and when water runs down the roof, it can freeze when it reaches the edge and form a dam. Then, just like any other dam, it then blocks the flow of water by preventing melted water from the upper section of the roof from flowing off the roof. This melted water then pools at the dam and leaks under the shingles, into the attic space, and down the walls.
What are roof cables?
Roof cables are thin electrically heated cables that are installed around the edge of the roof to melt any ice that may be trying to form there. They can be used on asphalt shingles, fibreglass shingles, steel, and cedar shake roofs to help prevent ice dams.
The best time to install roof cables is spring, right after the last thaw. Trouble spots are still fresh in your mind, and often are still evident on the roof.
The ambient temperature is still cool, making it easier to complete the task without damaging any shingles.
The second best time is LATE summer (or in the case of this year- cool summer). During the hottest days of summer shingles are too hot and soft. They can be easily damaged – even by stepping on them – at the hottest time of year.
Late fall can be tricky as temperatures approach freezing; shingles can be brittle if they are too cold and can break during cable installation. If you must install in the fall make sure the electrical contractor provides a written guarantee.
A licensed electrical contractor will provide the correctly sized circuit, wiring, and GFCI receptacle to feed the roof cables. He can also help you select (or provide you with) a good quality set of cables in the proper length.
A certified roofer is the right man for the installation. He will have knowledge of the roofing system, proper venting, ice and water shields, valleys and caps, as well as an understanding of the special requirements of various roof claddings. (Basic shingles, fiber glass shingles, cedar shakes, steel, slate to name a few.)
He will also have the expertise to avoid causing any damage to the existing shingles and will be able provide you with valuable information you may need to make the attic airflow optimal. Beware of “Yep, all we gotta do is throw up some cables and yer good ta go.”
Your roof cables don’t need to run continuously between November and April. However, cables must energize and warm the roof area before the ice forms.
The thermal controller should only allow the cables to come on when temperatures reach about 2 degrees C. This can easily be done automatically by plugging in Thermo Cube or Easy heat thermostatically controlled device between your outlet and the cables.
If you already have roof cables on your roof, make sure to add these inexpensive controllers.