Roof Heating Cable Calculator estimates the cost and length of heat cables for your home, based on your roof length and overhang width.
If snow and ice accumulate on your roof, installing a roof heat cable is an easy and effective solution to melt the ice dams before they cause major damage.
Materials List:
Total Cost:
How To Estimate Roof Heat Cable Length
You will need to measure your roof eaves (horizontal roof edge where gutters are attached) – this will be the value of “Roof Length”. Enter this into the calculator.
If you have valleys with ice dam problems, also include total length of valley, where you will install the cable.
Loop Height: we recommend the loop height to be 12″ longer than your overhang – this will ensure that your heat cable is melting the ice 6″ past the exterior wall of your house. Note that manufacturer’s recommendation is overhang width + 6″. However, in our experience this is not enough to properly remove ice dams.
Also consider that steeper roofs definitely need loop height to be at least 12″ longer than overhangs. A 12/12 slope increase distance up the slope by a factor of 1.41 – therefore if your overhang is 24″, you need 36″ loop height just to get in line with the outside of the exterior wall.
Loop Spacing: the loops are spaced 24″ between peaks and valleys horizontally, and a clip is place every one foot of roof edge. There are 19 clips per pack. Divide the roof edge length by 19 (and round up) to get the number of clips that you will need.
Average Cost To Install A Roof Heat Cable
It is fairly simple to install this system yourself – all you need is a ladder that is long enough to reach your roof, and a ladder stabilizer bar to make sure it doesn’t slide to the side, and to prevent falls / injuries.
DIY EASY HEAT INSTALLATION GUIDE (PDF) – Here is a complete installation guide for easy heating products, which can also be used as a reference for other brands.
If you opt for hiring a roofer – we still recommend that you buy the materials yourself, and agree on a set price for installation labor only. The reason for this is that most contractors will put 50-100% premium on materials, so you can save $100-300 if you purchase everything yourself.
The average cost to install 100 feet of heat cable on the roof only is about $300-400 (labor only, excludes materials). When you add materials, at the price of about $2/sq. ft.., you are looking to spend about $200 for 100 feet of cable. Thus your total cost when hiring a contractor will be $500-600.
Putting heat cables inside gutters and downspouts will add about $200-300 for every 100 feet of roof edge length.
How Much Does It Cost To Operate Roof Heating Cables?
As mentioned above – you will use about 8W per linear foot of ice-melting cable. A typical 120 foot long roof edge with 6-12″ overhangs and no gutters deicing, will need about 291 feet of cable. That equals to 2.3kWh per hour or almost 56kWh per day of continuous operation.
With US average electric price of $0.13/kWh, you will be spending $7.25 per day, if your system is running full 24 hours. A full month of non-stop operation would cost about $217.
In Massachusetts, our electric costs are about $0.23 / kWh. This means that running the deicing cables for a full day would cost me almost $13/day or $385 per month!!!
To prevent your system from being on all day and wasting electricity, you can either manually turn it off (when there is no snow/ice on the roof), or use a snow/ice sensor. It will automatically turn off the power, and save you tons of money on operating costs!
These sensors are designed for a maximum of 120′ of cable length and 1200W max load.
Estimate Electric Circuit Load
Most roof heating wire products are 110V, with rated electric use of 8W per linear foot. This means that you should not install more than 190 feet of heat wire on a single 15A circuit.
Also keep in mind that you need to run your cable from the nearest power outlet to the roof – a distance that is about 15 feet on average (unless you run your waterproof extension cord right to the roof).
Because most people will plug in their heat cables directly into an exterior power outlet, we add 15 feet to the total cable length.
Moreover, if you are using a 200′ or 240′ long heat wire, you should absolutely plug it into a 20A outlet. Otherwise, you will overload the circuit, and your breaker will pop. This can cause unwanted ice dams damages, while you may be unaware that your deicing system is not working.
Why Is Ice Dam Prevention So Important?
The obvious reason for protecting your roof from ice dams is that they cause serious damage to the roof itself and in worst case scenarios to the interior of your home. Here are some of the most common problems that a built-up of ice can create:
– Roof leaks
– Loose or damaged shingles that need to be replaced
– Torn off or damaged gutters
– Wet attic insulation that will need to be replaced
– Mold in the attic
– Stains on the ceilings and floors of the top floor in your house
– Chipping or peeling interior paint
Typically, if ice dams are not dealt with in a timely fashion, the destruction they do is compounded – in other words you will be seeing a number of issues from this list all at once.
The average cost of repairs is $1,500-2,500+, depending on what needs to be done. However, it can be as high as $7,000+ if your home will require mold remediation.
Ultimately, its all about the cost. Spending money upfront on an expensive and advanced roof-deicing product, such as Perfectly Clear, costs significantly less than repairing damages from unruly ice dams.
Are Roof Heating Cables The Best Solution For Ice Dams?
When it comes to products that can help fight ice dams, there are many options to choose from, ranging from very cheap to very expensive.
Usually, the most popular option is to install roof heating cables, because they are fairly inexpensive and work in most cases.
However, if roof heat cables have not been working for your house, the best alternative is to install a metal roof, which provides a much more permanent and solid protection against ice dams.
Here are a couple of questions to think about to help you choose the right product:
1. Does your home routinely have serious ice dams every winter? If your house does not have major problems with ice and snow, spending a lot of money on expensive systems may not make sense.
2. Do you regularly spend money on cheap ice dam solutions and sometimes roof repairs? In this case, you may want to consider more advanced, permanent solutions.
3. Do you have an old roof that needs to be replaced this season? If so, you may want to consider installing a metal roof. While its very costly ($9,000-13,000 for a 1,500 sq. ft. roof), it provides a permanent solution to leaks, ice dams and all roof related problems.
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For over 20 years Leo has run a successful roofing business in New England, specializing in metal roofing, as well as cool flat roofing technologies. Having replaced and installed hundreds of roofs in New England, Leo has first hand experience with pretty much every residential roofing material and roofing manufacturer available in the US.
I have a snow belt going along the eaves of my dormer roof about 30 ft. I want to use snow heater wire to keep snow from collecting on the metal snow belt and falling down like it did last year. The width of the snow belt is approximately 30 inches. How much heater wire is required and approximately how much current will it draw?
Chuck,
Current you will need to look up on manufacturer’s website, and it varies by length of cable. But you can definitely plug them into 15A outlets.
As for prevent ice / snow from falling off the roof. We had similar situation, and client had ice damage. So we installed snowguards (not heat cables).
Here is a video: https://www.youtube.com/watch?v=bjcbRGArdD0
If you still want to use heat cables, you also need to figure out how long you ice belt panels are (not just how wide). Most likely they are 16″ wide, so you can do heat cable diagonally across each panel once or a V shape. This V-shape will nearly double the length of your cable. Still the ice/snow will fall off, but in smaller chunks.
As for length – I don’t know the dimensions of your Ice belt panels. You should refer to this installation manual.
Good luck
I didn’t see any patter or measurements for installing the cable in a valley. Please clarify.
George
Standard pattern is 12″ step. So UP / DOWN = 24″
How far you go up the slope depends on the overhang width. Normally, you cover “freeze zone”, so overhang + exterior wall + 6″
So if overhang is 12″ and slope is 8/12, that is about 15″ up the roof. Add 5″ typical exterior wall + 6″ = about 30″ up the roof.
The last 6″ is not critical, but I recommend it. Extra cost for typical roof would be maybe $50.
Hope this makes sense. Here is the PDF with installation instructions: https://www.roofcalc.org/wp-content/uploads/Easy-Heat-Roof-De-Icing-Cable-Installation-Guide.pdf
Leo
Fantastic guide thank you so much. I know these are designed for a sloped roof, however, I have an old 1.5 story home, the master bedroom is upstairs and makes that part of the roof have very little slope, there is little to no overhang. I’m hoping if I make the loop length 36″ it will prevent buildup despite the lack of gravity.
Benjamin, did you ever install that? if so, maybe send pictures, and let us know how it worked out 🙂
Does the valley calc need to be entered as 6 or 12 feet if I want the cable to extend up 6 feet and then back down to the zig zag?
Rick,
EasyHeat does not specify “zig-zag” pattern in valley … so our calculator assumes that you will run a straight line up and down the valley … about 6″ away from valley center … so you need to enter actually length of valley, and it will double that to give you cable length.
If you want zig-zag with 6 feet “width” (is that total width or 6′ in each direction?) … I assume total width, so 3 feet from center, you need to multiply valley length by 3.2 … that assumes 1 foot distance between each step (peak), which is standard heat cable spacing.
Keep in mind that 3.2 multiplier is only in your case of valley, and is not to be use for calculate heat cables along the roof edge. There we use different formula, as heat cable MUST go beyond the exterior wall of the building to be effective. Hence we use roof overhang to calculate how long is each “zig-zag” .
Hope this helps.
Cheers, Leo
Hi,
Any expirence with concrete roof reinforced and in fresh concrete fit natural stone slate anchored to metal mesh.
There on mesh is also on south west side fix plastic pipe that cncrete will be as well as heat acumulation for hot water prearation.
The concrete is done from expanded clay, sand and cement, so to be thermo and hydro insulation and it is lightest in comprataion with stone concrete.