How to Prevent Ice Dams on Your Home – Answers from the Experts
To be frank, the entire concept of ice dam prevention is a little bit disingenuous. There are certain circumstances where even the most well constructed, well insulated and ventilated roof system will get ice dams. Those situations are rare, but they do occur. When we talk about ‘prevention’, what we are realistically discussing is the field of work aimed at either reducing the likelihood of ice dams or minimizing the impact of ice dams if they do occur.
Two Approaches to Ice Dam Prevention:
We break ice dam prevention into two broad categories; Architectural and Non-Architectural. Architectural solutions involve modifications to the existing structure to alter the problematic thermal characteristics that are contributing causes of ice dams. In contrast, Non-Architectural solutions are comprised of the work done to minimize the impact of unwanted roof and gutter ice accumulations when they are likely to begin.
It’s seldom the case that a single home medication, once implemented, will permanently fix an ice dam problem. More often than not ice dam prevention involves a combination of changes in order to have a significant impact.
A very standard ice dam prevention project for The Ice Dam Company might involve enhancing or replacing the insulation in the attic or roof system, adding ventilation and sealing all of the air-leaks between the heated spaces and the attic and roof framing. Usually, this combination of endeavors yields good results. Sometimes it is necessary to alter the roofing system itself. Normally, this means installing a single ply roof system such as hand-soldered copper pans or a rubber membrane. Single ply roof systems are quite resilient in the face of ice dams but they will to work in all areas due to aesthetics. We will dig further into each of the three basic architectural solutions in other Case Studies.
Certain ice dam creation factors cannot be addressed through Architectural solutions such as insulation, ventilation, air-sealing or roof system enhancements. Case Study #19 discusses the relationship between the sun and ice dams. We recently installed heat tape on a 6 year old, $3.8 million dollar home. The homeowner had spared no expense relative to energy efficiency in the original design and construction. That was not the issue. The problem was simply that the sun was melting the snow on an exposed roof plane higher on the home which resulted in melt water running down to a cold eave area that was hidden from the sun. There it would re-freeze in cycles to create an ice dam that kept coming back year after year.
In terms of ice dam prevention, there is a small set of options available that fall outside of the Architectural solutions. These involve systems to manage snow and ice accumulations as they develop on a roof. The most popular Non-Architectural ice dam solution is heat cables. Otherwise known as heat tape and roof deicing, heat cables are wires that warm up in response to electrical current. Typically, heat cables are installed in a serpentine or zig-zag pattern on a roof along the eaves. To be clear, heat cables do not resolve the underlying issues related to why ice dams are happening rather they help manage the issue of unwanted ice accumulations when the conditions are ripe for their formation. A common complaint about heat tape is that it does not address the real issues causing the ice dams. This complaint is justified because it is true. That said, heat cable systems can be installed on a home for a fraction of the cost of traditional Architectural solutions. Many homeowners are not in the position to spend $5,000 to $25,000 for Architectural ice dam solutions making the idea of a $1,000 heat cable system very appealing. We do both approaches every day.
We would be remiss in not mentioning the very most basic thing you can do to minimize the likelihood of ice dams; Roof shoveling. Diligently removing the snow from your roof can greatly reduce the likelihood of ice dams. Unfortunately, some roofs are too high or have areas inaccessible to the average homeowner, making roof snow removal an ineffective approach to guaranteed ice dam prevention. Removing all of the snow from the roof planes affected by the ice dams is very important. See the Ice Dam Company Case Study #3 that discusses a phenomenon called the ‘Double Dam’.
How Roof Pitch (Roof Slope) Affects the Impact of Ice Dams on Standard Residential Construction
Fact: The Flatter the Roof, the Less Ice it Takes to Cause Problems
As discussed in previous Ice Dam Company blogs and Case Studies, there is a strong relationship between roof slope and the timing and likelihood of damage as the result of ice dams. Specifically, low roof slope areas are far more susceptible to damage by small ice accumulations than areas of steeper slope. Why? It comes down to basic geometry. Study the diagrams, below. You can see that the high slope roofs (C) require a pretty thick ice dam to form before water will begin leaking into the home. Eave depth plays another important role. See Case Study #10 for more information.
Ice dams create leaks when melted water from higher on the roof slope hits a dam of ice and is forced to travel backwards, up and under the plus of the roofing system (typically asphalt shingles). When that backward motion occurs outside the plane of exterior wall (dotted red lines in diagrams), the water runs down the exterior wall or through the soffits (zone indicated by happy face). As soon as the water falls on top of the top plate of the wall it seeps down through the wall causing damage to insulation, finishes and flooring (zone indicated by sad face). Truthfully, water coming through your soffits is nothing to be happy about. The next step is the interior of your home so it is considered an emergency in terms of the progression of the ice dam. As mentioned before, if you see ice coming through the soffit or down the exterior wall, it’s time to get that ice dam removed.
Wayzata Residence with Low Pitch Roof Suffers the Consequence
Seen below is a home in Wayzata, Minnesota where we steamed an ice dam a couple of years ago. The construction assembly was typical 2×6 walls, 12″ eaves, 6″ facia with a 2/12 roof pitch. From the ground, no ominous, threatening icicles could be seen, just a couple of pathetic whiskers of ice off the face of the gutter through the soffit (D). Pan out and you see that the entire exterior wall was bleeding ice through the siding. This is bad. This home had massive damage to the interior insulation, drywall and flooring systems.
As discussed in Case Study #06, low pitch roofs also tend to create ‘deeper’ ice dams (E), where the ice has grown further up the roof. Deep ice dams take far longer to remove.
No icicles does not mean no ice dams.
Low pitch roofs present higher risks in terms of how quickly small ice dams can cause big problems.
Ice or water coming down the exterior wall in below freezing conditions is bad. Very, very bad.
There is a lot of misinformation out there on the topic of ice dams. Our goal here is to be the single definitive source for all things relating to ice dams. Towards that end, here are some common misconceptions about ice dams, roof snow, roof ice and gutter ice removal.
FACT: Ice dams can occur with virtually no snow on your roof. It’s a question of ice accumulations. It takes very little actual moisture to form ice dams. Even a dusting of snow can create a problem. Of course it is most often the case the thick snow accumulations create ice dams more quickly, but don’t be fooled into complacency because it’s a low snow season. See Case Study #09.
FICTION: Gutters have something to do with ice dams. The truth is gutters have nothing whatsoever to do with ice dams. See Case Study #03 for proof. If your home is prone to ice dams you will get them regardless of whether or not you have gutters. If you have gutters they will fill with ice and provide a foundation for the ice dam above. True. If you don’t have gutters, the ice dam simply builds on the cold edge of the roof. We provide ice dam removal for many homes each year that do not have gutters. In fact, some of our repeat clients have removed their gutters upon the advice of a dumb person only to be shocked that the ice dams came back the season after. Whoops.
FACT: Gutter systems can be damaged by ice. We see it every year. A section of otherwise fine gutter is either on the ground or hanging pathetically off the edge of the roof, filled with ice. Ice weighs about 60 pounds per cubic foot and gutters are not designed to tolerate that sort of load. It’s important to initiate gutter ice removal sooner than later for this reason. See Case Study #11 for common ice dam damage.
FICTION: When it comes to insulation, the more the better. Improperly insulated homes are just as bad as under insulated homes when it comes to ice dams. We have fixed countless bad insulation jobs for this reason. Specifically, we frequently find insulation done in such a way as to inhibit proper ventilation. Moreover, if you don’t address air leakage into the attic or rafter spaces, all the insulation in the world won’t prevent ice dams. See Case Study #04 for details about good eave ventilation.
FACT: You can’t always see ice dams from the ground. It’s true that you can often spot a monster ice dam quite quickly. It’s easy to spot the two foot icicles and the little adjoining glacier on your gutter. The sneaky ones are usually above skylights or in roof pan areas far out of sight. Sometimes ice dams grow up valleys and on top of dormers making it almost impossible to identify from the ground. See Case Study #02 for more information on where ice dams form on residential homes.
FICTION: Salt socks are a smart way to address ice dams. People use pantyhose, old socks and store-bought cloth tubes filled with a variety of ice-melting compounds for removing ice dams. Corrosive substances like rock salt, sodium chloride, calcium chloride, magnesium chloride and more to melt channels through their ice dams. Some compounds are better than others, but all present risks you should keep in mind. Some of the aforementioned chemicals affect the integrity or color of your roof, some are corrosive to the aluminum when gutter ice is removed this way, some are corrosive to valley metal and other flashings, some damage plant life as the water drains below. You are rolling the dice when you go this route so be aware. See Case Study #13 for more information on salt socks (salt in pantyhose).
FACT: Ice should be removed by steam. Here is the skinny. We are roofers and have fixed hundreds of roofs that have been damaged by well-intentioned professionals with hammers, picks and hatchets in their pursuit of removing ice dams to help their clients. The damage we have found caused by the less-than-professional souls is almost funny if it wasn’t so serious. In our years we have seen jobs with picks and hammers where removing ice dams was done successfully. It get’s down to the question of whether you want to take that risk? We strongly advise against the hack-a-teer approach even if it is a little cheaper. Roof Ice and Gutter Ice should always be removed with steam.
FICTION: Ice dams need to be thick to cause a problem. Ice dams as thin as one inch can cause big problems. A good general rule is that the steeper your roof, the thicker the ice dam has to be to cause problems. On lower pitched roofs even a thin ice dam can hurt.
FACT: The leaking caused by ice dams may not show up right away. It would be nice if water stains or mold manifested immediately upon entering your home but it simply does not work that way. Often the water that ice dams push into homes travels around wall and ceiling cavities, trapped by vapor barriers and other materials until it finds the path of least resistance to escape. By the time you see water inside, it’s usually been there for a while, which results in mold and mildew.
The Factors that Determine Ice Dam Removal Cost and Pricing
Ice Dam Removal Pricing
Generally speaking, you can expect to pay somewhere between $300 to $600 per hour for ice dam removal with steam. As much as you may not want to hear this, with over 25 years of experience behind us, we can tell you that the primary driver for ice dam pricing is classic supply and demand. Every market will have a different demand for ice dam removal and a different supply of qualified contractors to perform that work. (See Econ101 from your freshman year for further details). Back to the word “qualified”. There are dozens of companies in the Twin Cities market right now who are using ice picks and hammers and axes to remove ice dams. They normally charge less per hour than ice dam steaming contractors. There are also scores of competitors using high temperature pressure washers and calling them steamers (hint: 2 of the top 3 Google results in Minnesota). Yikes. In the Minneapolis market we profit by following the work of the aforementioned “professionals” by repairing the damage they’ve done each winter with pics and pressure washers. It’s hurts to pay for ice dam removal. It’s extra painful to pay for repairing the damage left behind by losers.
Ice Dam Removal Speed
There are many factors that go into determining how long an ice dam takes to remove:
Roof height (Higher = More difficult)
Roof pitch (Steeper = More difficult)
Snow load (More snow = More time)
Site protections time (Property under the work area needs to be protected to prevent damage from falling ice and snow)
Ice dam thickness (Thicker = More time)
Ice dam depth (The further it has grown up the roof, the longer removal takes)
Outdoor temps (Colder = More difficult)
Ethics (Lower ethics = More time spent)
Having two members to the crew is not only important to safety, it is essential for efficiency. One guy cuts and one guy throws the ice chunks.
To Chunk or Not to Chunk
There is a big difference between ice dam removal COST and ice dam removal PRICING. Pricing is what one typically pays per hour for the work to be performed. Cost relates to how long it takes to do the job. In our list of the 8 factors that determine ice dam removal cost, #8 is the most important. That’s what the photos in this case study are meant to illustrate. Ethical ice dam removal guys do it like shown and they use steam, not high temperature pressure washers. It’s called ‘chunking’. The idea is simple. Use the steamer to cut the ice dam into chunks that can be picked up and thrown off the roof. Cutting ice is the part of the job that takes the longest. Add to cutting time, add to the job cost. The alternative is to use the steamer-or pressure washer if you’re totally smarmy-to methodically melt away ALL of the ice from the roof, one square inch at a time. As shown here, one only needs to actually melt about 5-10% of the ice in order to remove the ice dam. Make slots and undercut. It’s that simple. What the less ethical players do is also simple. Melt all of the ice, milk the clock and watch the dollars add up.
The Truth About Gutters and their Relationship with Ice Dams
In 2011, Ice Dam Company owner Steve Kuhl wrote a nationally published article about ice dams for the Journal of Light Construction. One of the topics that receieved the most attention was the notion that gutters have nothing to do with ice dams. Here is a deeper look at that assertion.
There is a great deal of confusion and misinformation about the relationship between gutters and ice dams. Many people are under the misconception that gutters cause ice dams or that gutters filled with ice can cause water to back up into homes. Not true. We repeat. Gutters have nothing to do with ice dam formation or severity. For this reason, buying systems that heat gutters in order to prevent ice dams is a total and complete waste of money.
We know that ice dams occure when:
Escaped heat from the inside of the home warms the roof deck.
Melting snow results in water that runs down to a cold, unheated area of the roof (frequently the eave, as shown below).
That water freezes, forming ice. After many of these cycles, that ice piles up to form an ice dam.
Study the illustrations below. These are identical eave designs, one with gutters, the other without. The Area B in the diagrams below is referred to as the ‘cold edge’ of the eave because heat from the interior of the home doesn’t travel that far. Fact One: Whether or not a home has gutters, a cold edge will still exist and this is where ice dams form. Fact Two: leaks from ice dams occur in Area A, at the leading, top edge of the ice dam where water–with nowhere else to go–is forced up under the roofing material and into the home. Put another way, if the home in Figure 2 had bad leaks inside, those leaks would not be eliminated whatsoever if we took a chainsaw and cut off the gutters along the red dashed line (C). Moreover, if we heated the gutters using a fancy electrical system, the likelihood of ice dams and the subsequent leaking would NOT be affected. Spend money on heat cables for the lower edge of your roof, not on heating the gutters only. High quality heat cables can be quite effective in preventing ice dams.
Figure 1: Ice Dam Without Gutters; Figure 2: Ice Dam With Gutters
None of this is to suggest that ice in gutters are harmless. We have seen many gutters damaged or destroyed by ice dams and that is a problem most homeowners would like to avoid. The point here is that, all else held equal, if a home is likely to get ice dams the addition or deletion of gutters will be of no consequence to the formation or severity of said ice dams. Likewise, for this reason, installing heated gutters or adding heating systems to existing gutters will have no affect whatsoever on the occurrence or severity of ice dams.
To read more Case Studies click here.
The piece also discusses other weather related problems and disasters that can happen from strong winter weather. Check it out. I am frequently interviewed from media and professional sources from all around the country on the topic of ice dams because I started The Ice Dam Company so long ago. We are in fact the largest and the oldest ice dam prevention and ice dam removal company in the country. Before the Ice Dam Company, no other company existed that specialized in this area of business. Now, of course, the web is littered with ‘experts’ and ‘specialists’ purporting to be leaders.
As the oldest ice removal company in the USA, we get asked to do some pretty bizarre stuff. We have done our share of strange ice removal projects but one that keeps popping up is removing ice from around cooling towers. What is a cooling tower? I don’t know exactly but I suspect it has something to do with providing chilled air or water to industrial equipment inside buildings. We have removed ice from around industrial equipment, like cooling towers, for many years. The tricky part is that they are normally fed by high voltage and natural gas so you don’t want an inexperienced person attempting this work. We slice away ice from commercial and industrial equipment using the same equipment we use for removing ice dams from homes. That is, we use our modified commercial steamers. Our guys were under such pressure earlier this winter that they worked from 2pm around the clock to 7:30am. The operation of an entire plant depended on the cooling tower being operational. We used two crews to complete the task. It wasn’t a cheap job but the cost of one lost day of production was far worse. Plus, according to the commercial HVAC contractor consulting on the project, there was a good chance that the cooling tower could be seriously damaged if the ice was allowed to remain in place any longer than it was.
Attic insulation contractor addresses ice dams with new insulation in Edina
Using the words ‘ice dam prevention’ in Minneapolis is a dangerous gamble. It’s true that with certain efforts one can greatly reduce the chances of getting ice dams, it is almost impossible to prevent them altogether. For example, we can do a top quality insulation and ventilation retrofit on a Minneapolis attic only to be thwarted by the fact that the homeowner likes to keep the attic at 90 degrees in the winter. That is a formula for ice dam disaster in Minnesota. There are a number of methods to employ in preventing ice dams (or reducing their severity, in some cases). Here are links to two such approaches used by our sister company, Kuhl’s Contracting, a nationally recognized ice dam prevention company.
Homeowners looking to fix or at least minimize the risk of ice dams in Minnesota are wise to look at the key contributing factors that spawn ice dams. Those are, the weather, insulation, ventilation, air leaks, personal lifestyle and home architecture. We are frequently successful in reducing and/or eliminating ice dams through the use of high performance spray foam insulation systems in combination with enhanced attic ventilation.
Removing Ice Dams in Minnesota: We Serve Many Areas in the Minneapolis Metro
The Ice Dam company based out of Hopkins, Minnesota, about 5 miles west of Minneapolis. We've done gutter ice removal, roof ice removal and ice dam removal all over the Twin Cities, on new houses and old ones.
Some of the more frequent places we've done ice dam services are: