December 22, 2021 11 min read

How To Prevent Ice Dams in Gutters and Roofs: 

In northern colder climates, a building’s gutters can freeze to a solid block of ice. The fact that during the winter season gutters can become locked in ice and entirely non-flowing and nonfunctional, makes the sensitive gutter installer think twice or even three times about gutter installation methods and gutter drainage design Yes, the thinking woman or man, should think about the fact that no water will flow when below 32 degrees Fahrenheit. The thoughtful gutter installer should recognize that in northern climates, a poorly vented roof combined with an improperly installed gutter, will experience gutter ice growth which can expand upward defying the laws of gravity. Improperly vented soffits or jets, and poorly installed gutters can experience ice damming, ice jamming, ice backup and leakage into the building. Before installing gutters in northern climates, it makes sense to understand some of the concepts and employ certain gutter installation techniques to defend against winter gutter ice problems. Gutter installers in southern climates can cheat and relax the gutter installation standards to some degree, but Mother Nature will make a fool out of those who do not follow the gutter rules in freezing climates.

Ice Damming on Roof and Gutters

  • Ice can cause water backup leakage
  • Inadequate fascia behind and above the gutter?
  • Gutter Ice Backup Leakage is preventable
  • Roof Ventilation & Insulation Decreases Roof Ice Problems
  • Gutter Strength to handle winter ice
  • Old Timer’s technique, Copper gutter lining worked well
  • Modern Gutter flashing, assure against gutter ice backup leakage
  • Decreasing Gutter Ice: Simple Passive Method, A Useful Technique
  • Gutter Ice Melting Cables: Active Method, Technique

 

gutter ice backup frozen downspout ice

Face the Fact Gutter Ice Doesn't Flow: Sometimes I have to laugh at the elaborate gutter designs I see with lengthy 50 foot stretches of gutter sporting two 90 degree miters attempting to carry the rain water on a long twisting and turning journey draining into a single well placed downspout at one end. People often resist the valuable suggestion of adding more downspout drainage to improve gutter performance. Such elaborate gutter designs are often due to the owner attempting to avoid draining onto certain areas that might end up on a deck, in the basement, or flowing over a walkway. People often ask me “ How do I stop my gutters from filling with ice?. Unfortunately you cant avoid iced gutters. Those owners might consider a better gutter design when they consider the fact that nothing flows when there is ice in gutters and downspouts. Often, gutter drainage stops due to ice and the water and ice ends up on the walkway or in the basement anyway. Gutters and downspouts will fill with ice and become completely non-functional at times during the winter; the proper gutter design and installation should begin with this in mind. The homeowner or building owner must have a building envelope that does not experience real problems when the gutters are locked in ice and nothing is flowing. Additionally, the gutter system should experience no leakage to the interior of the building, even when the gutters are full of ice and it begins to rain. Sometimes gutters do not work, so let's just make sure gutters are installed in such a way that they don't leak into the building regardless of the weather conditions. The properly installed gutter with the properly ventilated roof and soffit will not experience water infiltration or condensation moisture.

Some Winters are Worse: I gained an understanding of winter gutter requirements when I spent 25 years roofing, right through the winter in Rhode Island. During extreme winter weather, we might only get three days of work per week but we roofed all 52 weeks of the year right through the summer and the winter seasons.

gutter ice damm gutter ice backup icicles from fascia and soffit

Some winters are extremely mild while other winters pack a severe punch of many extremely cold days in a row without experiencing a thaw. Entire communities can go many years in a row without ice damming on roof; then one particular year they can experience extreme cold conditions day after day that causes huge numbers of roof edge leakage problems and gutter backups that wreak havoc throughout entire neighborhoods. The problems usually reveal themselves on the northern colder side of the home first. Homes that had passed the test for many winters in a row, can suddenly realize that their roof and gutters had been improperly installed without their knowledge. They passed the test during the many fairly mild winters, but mother nature has a way of revealing poorly vented roofs and inadequate gutter installations in northern climates. When the winter weather is less severe, the problems are not necessarily flushed out. They are “ out of sight and out of mind.” But when the weather becomes more severe for extended periods of time without reprieve, the ice damming and gutter ice backup problems become worse and sometimes extensive.

Roof Ice Dam Prevention: Gutter Ice Backups and Leaks are avoidable: Ice can accumulate and grow. Continued freeze and thaw cycles can allow gutter ice to grow upward. Ice growth can trap pools of water up against your roof and fascia that cause the simulation of the thawing water level rising or moving upward or backwards and leaking over the fascia, into the soffit and into the home. The properly installed roof with the correct roof and soffit ventilation and a correctly installed gutter, may experience some ice growth but will not experience leakage into the soffit or building. Below, this article explains certain techniques which can be employed to decrease the unnatural buildup and unnatural melting of gutter and roof ice. Certain roof fascia flashing techniques can also be used to assure that even when ice forms and grows, it will not result in water infiltration.

Roof Ventilation Solves Ice Dams and Gutter Ice: Without proper roof ventilation, ice buildup and roof edge ice formation can be more extreme and problematic causing ice dam damage. Poorly ventilated roof, plenum and attic areas not only can experience an increased rate of exterior ice growth, but also unnatural roof ice melting supported by interior heat loss which increases the chances of an ice melting back up. Insulation and ventilation go hand in hand. The better the attic and outside wall insulation, the lesser the burden on roof ventilation. Excessive interior heat loss causes roof and gutter ice melting. Often exacerbated by snowfall, excessively frequent freeze and thaw cycles of roof and gutter ice caused by interior heat loss, will make the ice damming on the roof grow larger day by day. This problem is usually evident at its worst, at the location where the roof meets the outside wall (usually first evident on the north side). The heat from the entire height of the outside wall will naturally migrate upward eventually leaking out through the wall-top into the attic or plenum area. In an improperly vented home or building, the heat loss accumulates and adds warm energy to the underside of the roof sheathing and to the ice buildup on the roof causing roof warmth , melting conditions and leaks. In the correctly vented scenario, that heat loss is carried away by a stream of airflow so that the roof’s underside is not warmed by the heat loss. Roof ventilation assures that the underside of the roof sheathing is practically the same temperature as the outdoors, so that no roof or gutter melting occurs due to the heat lost from the interior. The correctly vented soffit, jet and roof area does not experience freeze / thaw cycles that are caused by interior heat loss. When natural gutter and roof ice does occur, the melting of such should be entirely natural fueled by the outside conditions, causing no problems. Roof ventilation also bears the burden of ventilating out moisture, however that is a discussion for a different article.

Most Gutter Backup Leaks: Inadequate fascia coverage above the gutter: Most of the time, when ice conditions cause a gutter to leak into the building, it is most often due to an inadequate amount of fascia extending upward covering that area above and behind the gutter. When a gutter clogs and backs up due to wind or ice, the properly installed gutter and soffit will have adequate fascia height above and behind the gutter so that when the gutter wants to pour water backwards for whatever reason, that water meets the fascia which stops water infiltration and assures that the water is kept out of the building envelope. Those who install gutters will often mistakenly position the gutter too high on the fascia board thereby decreasing the amount of fascia protection above the gutter and adding susceptibility to backup and leakage. In most cases in the Rhode Island geographical area, assuring that you have 1.5 inches of fascia above the gutter for protection, will be adequate. Most of the gutter ice leaks I observed over the years, had little to no fascia coverage above the gutter; or perhaps the fascia had a leaking joint or rotted area.

An Old Timers Copper Gutter Solution, Problem Solved:  I illustrate this solution, as an example that can help the reader understand further. Forty years ago, it would be common, as a contractor, to come across a home with a wood gutter that had been experiencing ice back-ups. At that time, we would remove the lower courses of roof shingles in order to entirely line the gutter with 16 ounce flat locked soldered sheet copper. The continuous copper gutter lining would extend 12 to 18 inches onto the roof and then the roof shingles would be reinstalled , where removed, but they would be fully sealed down to the copper flange with asphalt. By lining the gutter and extending the lining up onto the roof, we are essentially closing the fascia gap above the gutter so that water can not build up and breach the gap at the top of the fascia. This solution worked well even when there was a ventilation or insulation problem that had not been solved. Unfortunately, installing copper gutter linings is very expensive and you can not seal to or connect to an existing installed aluminum gutter in the same fashion.

An Aluminum Gutter Fascia Apron Must Be Locked: While very few gutter installers will actually use this technique, the Alcoa Aluminum Gutter System originally required that a sheet metal roof fascia apron should be locked onto (sheet metal formed lock joint) the back of the 032 Aluminum gutter to guard against backup. The sheet metal lock joint is not entirely waterproof, but it was usually enough to help guard against ice back up. A simple slip joint or overlap joint is never sufficient because water backing up will meet no resistance and will easily breach a simple overlap joint.

If You Get a New Roof and Not a New Gutter, You Have Risk:  It is horrifying to realize that most homeowners get a new roof and do not have protection against gutter ice backup; and they do not know it. If your home has a common, seamless k-style gutter, and you get a new roof without removing the gutter, then your gutter has a significant chance of experiencing an ice backup that can leak. If the roofer were to guarantee against gutter ice backup, then he’d either have to seal the roofing to the gutter or flash behind it. You can not seal to an existing installed aluminum gutter because the crossbar hangers obstruct the process, and one would need to remove the gutter in order to install sheet metal flashing behind it, therefore if a home receives a new roof and the k-style gutter was not removed, then there is likely a gap at the drip edge that is susceptible to ice backup leakage. The fact is that most roofs and gutters are susceptible to backup, and only stellar caring ethical contractors are talking about it. Nobody wants to drive the cost of a roofing project higher, but building owners deserve to know that a new roof does not necessarily mean any defense against gutter ice backup.

Ice Dam Prevention Products: Over the years as a contractor, I returned all phone calls and worked diligently to solve customer water problems. Those contractors who do not return phone calls and do not perform repairs, often do not learn ways to combat extreme conditions. I cared about every customer so I learned some helpful techniques over the years. Nobody wants an ice buildup on roof causing leaks

Gutter Ice Backup Flashing, Roof and Gutter Removal Simultaneously Is A Must:  Back when I was installing new roofs, I had always been bidding against roofers who did not pay attention to guarding against gutter ice backup. I would provide the customer with the price for the new roof which does NOT include gutter ice backup protection. The gutter ice backup protection was an additional price to remove the gutter and install a custom brake formed sheet metal flashing bent at the slope of the roof to the fascia which closed the gap at the top of the fascia by providing one continuous sheet metal flashing that extended further up the slope of the roof as well as behind the gutter. The gutter would then be installed up against this fascia flashing and the roof drip edge would lap into the gutter. By installing flashing that extends adequately up the slope of the roof and both behind and into the gutter, gutter ice backups can no longer breach the fascia or roof and leak into the building.

Gutter Strength Technique: The standard k-style seamless gutter should be formed from .032 Aluminum. Aluminum gutters made of thinner Aluminum are substandard and cheap. .032 aluminum is the current industry standard for gutter sheet metal thickness. Downspouts can be thinner, however gutters should be .032 Aluminum or 16 ounce copper. To avoid gutter securement problems, I used to fasten each “hidden hanger” or horizontal gutter crossbar hanger with 2 screws each slightly angled from each other. To avoid problems from the weight of gutter ice as well as to provide a suitable gutter surface that could receive a heavy ladder hit without damage, I would install crossbar hangers 16” on center. Other contractors didn't have too many problems when installing hangers every 20 or even 24 inches, but I assured no future problems as well as decent installation speed by spacing the gutter hangers at 16 inch intervals. These techniques helped me to sleep well during howling wind driven rain storms.

Technique: Gutter Ice Decrease:  Passive Method without heat melting cables: If you have a gutter ice issue and you are not sure what exactly is the underlying cause, you can decrease gutter ice in a passive manner by filling the entire gutter with the GutterBrush simple gutter guard system. The presence of Gutterbrush in the gutter decreases ice formation. Old time contractors and Gutterbrush customers report improved winter gutter results and decreased gutter icing and icicles; and here is why. It is not uncommon to see a winter gutter completely filled with ice, but most of those start with snow on the roof and clogging the gutter. Snow falls and of course enters and fills the gutter. Eventually, either rain or melting occurs from the sun. It is very common for bright sunshine to melt snow on roofs during even very cold winter days. The melting water flows down into the gutter but the gutter is filled with snow. The snow impedes the melting water’s exit. You see it all the time, the gutter is clogged with snow so it fills up and drips over the edge all day until the temperature drops when the sun goes down and the gutter becomes a solid block of ice. The cycle has begun and that gutter ice begins to grow larger day by day. When a gutter has been filled with Gutterbrush, the snow will not clog the gutter, rather in most cases the snow only sits on top of the brush leaving the open protected flow area beneath the brush so that melting water and rain will flow unimpeded to the downspouts and exit. With Gutterbrush filling the gutter, the snow does not clog beneath the brush, the gutter doesn't pour over, and the gutter doesn't tend to even begin the ice process. Gutters filled with Gutterbrush experience less snow congestion, improved drainage ability, less ice and also improved melting because black bristles exposed to the sun add warmth and aid melting. Gutterbrush is a gutter guard for ice and snow; learn more at www.gutterbrush.com.

Technique: Add Gutter Ice Melting Cables:  To the above Gutterbrush scenario, if that does not solve the problem, consider adding gutter ice melting cables such as Frost King Roof De-Icing Cable Kits. Like Gutterbrush, these ice melting wires can be purchased from Homedepot.com in various lengths. They are available as plug-in ready electric gutter melting systems and they can be extended throughout the gutter while fully compatible with Gutterbrush; they are often used together to solve severe gutter ice problems. For melting roof ice, it is customary to install the de-icing cables in a serpentine fashion running the gutter ice melting wire both into the gutter and also extending it onto the lower three or four courses of roofing.

Northern winter climates cause gutter ice problems that get revealed when roofing and guttering are not installed thoughtfully and carefully. Roofing and guttering, when installed separately, seldom provide protection against ice backup. Proper installation techniques, education and awareness can help keep your gutters and your home out of winter trouble.

Alex O’Hanley

Former roofer of 25 years

Gutterbrush LLC, Middletown RI

Alex O'Hanley
Alex O'Hanley



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