The Relationship Between Sunshine and Ice Dam Formation
Ice dams happen when there is a section of roof that is above freezing (32°) where roof snow melts which then drains to an area that is below freezing, usually the eaves, where it refreezes. The source of this temperature differential is usually the result of interior heat loss, specifically via air leaks and insulation issues. In fact, according to our experience, 95% of our client’s ice dam problems can be mitigated or eliminated altogether through the modification of the thermal characteristics of the home. Still, we see ice dams on certain homes for reasons outside the scope of it’s architectural deficiencies. Homes with what we might call nearly perfect air-sealing, insulation and ventilation still get ice dams. This Case Study describes such a situation.
The winter sun hits Minnesota homes (and all homes in this latitude) at a low angle during the winter. The result is that certain roof slopes never see direct sunlight while others get hit quite directly. The above illustration demonstrates an ice dam situation that relates to the heating effects of the sun. Solar radiation warms the roof slope on the dormer (1), the resulting melt water drains to an area of the home (2) that never sees direct sunshine where it refreezes to form an ice dam (3). These are particularly challenging ice dams to prevent. Often times heat tape, also known as heat cables, are the only affordable option.
A Simple Explanation of Where the Water Goes When Ice Dams Cause Leaks
Where the Water Travels:
Water hitting the Top Plate of the wall (A) spreads out across the top plate, travels downward with gravity, working behind the Siding (B) the Housewrap (C), the Insulation (D), the Vapor Barrier (E) and the Drywall (F). Water always seeks the path of least resistance and therefore frequently shows up through existing penetrations in the ceiling such as lights. Water leaks caused by ice dams can travel many feet from the source before manifesting inside the home. On homes built with vapor barriers on top of the ceiling finish, water will sit on top of the drywall and soak the insulation before leaking inside.
Ice Dams on Mansard Roofs Can be a Seriously Big Headache to Remove
Roof Styles Affect Ice Dam Severity
As discussed in Case Study #16, there can be some serious problems if homeowners decide to remove snow from only a portion of the roof plane affected by ice dams. We call it the ‘Double Dam’, which refers to the fact that ice dams can grow much further up the roof when only lower sections of snow are removed (commonly done with roof snow rakes because they can’t reach high enough on the roof).
Mansard roofs, such as this one from Edina, Minnesota, can create massive ice dams when the steep pitch (B) is cleared of snow. This is amplified when the slope has directional bias towards the north because the sun will not help melt the ice as it accumulates. In the photo, below, we see two ice dam problems on this Edina mansard roof. The traditional location (A) is exacerbated by the low roof pitch (Case Study #09 explores the relationship between roof pitch, or roof slope, and ice dams). Area B has an ice dam that covers the entire span of the roof slope. This took many hours to remove even with our commercial ice dam steaming equipment.
Which Ice Dam Do You Want?
Ice dam #1 is not the one you want. Ice dams like this take hours to remove with steam, which is the most efficient and safe method for removing ice dams. This ice dam is thin but it has grown many feet up the roof. Ice dam #2 is an easier problem to resolve.
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.
Steaming Ice Dams is the Fastest, Safest Way to Remove Ice Dams in Minneapolis
Why Use Steam?
When used properly, a commercial ice dam steamer is the best way to quickly and safely remove an ice dam or other unwanted ice accumulation. Like anything else, it’s possible to use a steamer improperly and damage property. That’s why you should hire an experienced ice removal company. Far more common is damage done to roofs using high temperature pressure washers. Most of our competitors that claim to be using steam are actually using high temp pressure washers. It’s the dirty little secret in our industry. Want to know the easiest way to tell the difference between a steamer and a high temperature pressure washer? If the gun has a trigger, it is NOT a steamer. It’s that simple. More information about Ice Dam Steamers vs High Temp Pressure Washers can be found here.
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 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.
Okay, I have have seen it all now. I’ve kept quiet for the last two years but I can’t do it any longer. I just spoke with a woman whose roof was scarred up by a ‘professional’ using a ‘steamer’. The only catch was that the guy wasn’t using a steamer; it was a pressure washer . A number of companies are using high-temperature pressure washers instead of steamers to remove ice from homes. At first glance it might sound like a distinction interesting only to ice geeks. But alas, it is a pretty big deal. In short, pressure washers rely on pressure to remove ice (go figure), not on heat. ‘High-Temperature’ pressure washers operate at slightly higher temperatures than a typical water heater (120-170 degrees). A steamer is an entirely different machine. It converts cold tap water into true steam, which can only be achieved at 250 to 300 degrees. Again, why care? In short it comes down to the fact that steam remove ice much, much faster than high-pressure water. This translates in to time and money (less of both if you use a steamer). Steamers are not only the fastest choice, they are the safest. It doesn’t take a genius to understand that using high-pressure water near frozen roofing materials may not be the best plan. Invariably, regardless of the user, such machines strip off the granules on asphalt composite shingles. This voids manufacturers warranties and it reduces the lifespan of the shingle.
We own three high-temp pressure washers but would never consider using them to cut ice. To the average dude they don’t look much different than a steamer. Use one to cut ice and the difference becomes clear right away. For this reason, conscientious, ethical contractors use actual steamers. Besides The Ice Dam Company, there are a number of outfits in town that use true steamers, including Garlock-French and Absolutely Clean Window Washing. I’ve been around this industry for over 20 years and I have never heard a complaint about those shops. My point is, no matter who you hire to remove your ice, make certain their machinery is as advertised. It must be running at a minimum of 250 degrees over the entire course of the job to function safely and efficiently.
Here’s a great image taken by out friend Reuben Saltzman of Structure Tech, showing what kind of damage a pressure washer can do to an asphault roof when it’s used to remove an ice dam:
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: