The Ultimate Guide to Ice Dam Prevention

By Juno Construction

We compiled all the information we could on ice dams and put it all in place. In effect creating the most comprehensive guide to ice dams, ice dam prevention, and ice dam removal out there.
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Ice dams: the notorious icy mounds that cling to your roof eaves and cause serious damage to shingles, gutters, roof decking, attic insulation, and other important structural components of the home. The real reason these ice mounds form is that there is heat loss in the attic.

However, the root cause is rarely addressed. It’s the symptoms that get all the attention. That’s because it appears cheaper and more convenient to put a bandaid on a larger problem. If you are feeling confused by all the varying information out there, we hope this article will walk you through the long-term prevention, best temporary prevention and everything in between.


Long Term Prevention

If you interested in learning about ice dam prevention, you first need to understand how ice dams are formed:



Phase 1: Heat Loss

Heat loss in the attic is responsible for initiating the birth of an ice dam. Through conduction and convection, heat will travel from the conditioned living space into the attic where it will rise and collect near the roof deck.


Phase 2: Snow Melt

The warm roof deck will start to melt existing snow on the roof. This new found water will run down the roof and freeze on the cold eaves (see photo above). This process will continue over and over again every time a new snowfall occurs.


Phase 3: Dam Formation

From repeated snowmelt, a dam of ice will start to form on the eaves. Meltwater will become trapped behind the dam and start to flow under the shingles and cause leaks in the house.

For more info, check out our previous post of ice dams.

Now that you understand how these dams are formed, let’s talk about prevention
for the long term.

Get Professional Help

The first thing you should do is get a professional ( or more than 1) on site to do an attic inspection. The heat loss issue needs to be fixed and a qualified
professional will know how to get your attic working in tip-top shape. They will look at the following:



Air Leaks (Open Bypass):

Open bypasses in the attic is a huge issue. It means that heat from your living space is moving into the attic, heating the roof deck, and escaping outside. Does this explain your high heat bill? Any air leak or open bypass in the attic must be sealed in order to keep heat inside the conditioned living space. A bypass could be anything from chimneys, ceiling light fixtures, heating ducts, kitchen and bath exhaust fans, plumbing, electrical wires, dropped ceilings and soffits.


large open bypass along chimney in attic
Large open bypass along chimney in attic


open bypass around furnace vent
An open bypass around furnace vent


Insulation is very important for forming a heat-resistant barrier between the conditioned living space and the attic. Each region throughout the United States has requirements for attic insulation depending on climate.

The amount of insulation required is measured using the R-value which is an insulating materials capacity to resist heat flow. The higher the R-value, the higher the insulating power. In most snow belt areas, a minimum attic insulation level of R-49 is required in order to block conductive heat flow. If you are curious about the R-value requirements for your region, use Energy Star’s graph pictured below.



You can even take it one step further and venture into your attic to measure the amount of insulation present (your attic inspector will do this too). Take a measuring tape into the attic and measure from the floor to the top of the insulation. Then take that number and multiply it by 3.14. For example, if 4 inches of insulation were present, you would do 4×3.15 to get an R-value of about R13.

It doesn’t matter what zone you live in, R13 is not an adequate amount of insulation. Your attic inspector can walk you through this and answer any questions you may have.



Ventilation is the third component to a healthy attic (and ice dam prevention). A good working system will allow cool, fresh air to move into the attic at the eaves/soffit areas of the roof and will pull moist hot air out of the attic through ridge or exhaust vents.

This helps the attic to mimic the desired temperature of the climate outside. A functioning ventilation system will prevent moisture from breaking down attic components, avoid mold, lower energy bills, and sustain roof life. A good professional can tell you if your ventilation system is up to code and functioning properly.


Vaulted Ceilings

There is a myth that suggests vaulted ceilings are predestined to have ice dams. This is simply not true as long as the insulation has been installed correctly. It can be challenging to find an insulation company that really knows what they are doing. The need to be able to seal even the smallest of attic bypasses and also understand how ventilation works in order to prevent attic sweating.



Experienced insulators and contractors can tell you that most homes with vaulted ceilings built before 2010 were not insulated correctly. This makes long-term ice dam solutions more challenging for these types of homes. Often times vaulted ceilings only provide about 12 inches of space for insulation. There is no way a professional can access this space without tearing the roof off. It can be an expensive fix. The best thing to do in this situation is to plan to fix the insulation when you are installing a new roof.



Start planning ahead of time so you can budget properly. Correcting the insulation will keep your home and attic healthy and prevent potential ice dam water leaks from destroying your home.  To learn more read our previous post about the damages ices dams do to a home.


Short Term Prevention

Now you may understand what needs to be done to take care of ice dams for the long haul. You may be wondering what your options are if you aren’t prepared to
invest the funds necessary to fix the core issue. There is so much “fluff” out there on the internet and it’s hard to know who to trust. Many of the “solutions’” listed on the internet cause more harm and than good. The short-term solution below will cut through the fluff and give you an option that will be least damaging to your roof and will ultimately prevent leaks from occurring.



It may seem simple, but, the solution is….. shoveling. To stop ice dams from continuously growing larger, the water source feeding it must be eliminated. In this case, snow sitting on the roof is the culprit. When heat from the roof deck (from a poorly insulated attic) or the sun melts snow, it flows down the roof and freezes on the eaves. Once the ice mound grows large enough, it can trap water behind it which ultimately will move under your shingles and into the home. Get rid of the snow, get rid of ice dam related leaks.


What if an ice dam already exists? Don’t let anyone talk you into using harmful tactics like steam or pressure washing. The best solution is to gently and very carefully chip away the ice dam until there is about 1 inch of ice remaining on the roof. Stopping with 1 inch of ice remaining will prevent shingle/gutter damage from occurring. Make sure all the snow is shoveled off the roof and allow the sun to melt the remaining ice off the eaves.


While shoveling may be the best choice for short-term ice dam prevention, it is not flawless. There is still a risk of shingle damage if harsh tools are used. Metal shovels/tools should never be used on the roof. They pose the highest threat to shingle/gutter damage. Instead, use plastic snow shovels.

Another flaw to this method is the dangers of falling off a roof. Precautions need to be taken especially on steep slippery roofs. A harness should be used or consider hiring a professional who has experience navigating steep roofs.


In conclusion, it is important to get an attic inspection done whether you plan to fix existing issues or not. Gaining knowledge about your attic’s current situation is highly beneficial information. It allows you to start budgeting and create a plan for the immediate and/or long-term future. To learn more check out this massive post about ice dams.

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