What to Know About Preventing Ice Dams

Medically Reviewed by Mahammad Juber, MD on April 11, 2022
5 min read

Ice dams are a common problem in cold regions with lots of snow. There are some ways to get rid of them once they’ve formed — but their formation is never an ideal situation. In fact, it can be dangerous for both you and your house.

Consequently, your best course of action is to prevent ice dams before they begin to form. Your roof will last longer, and you can stop costly damages from accumulating. Plus, fixing all of the problems that lead to ice dams will make your home better insulated and secure in general. 

An ice dam is a large accumulation of melted snow that has refrozen near the edge of your roof. Dams will grow larger and larger the longer that you let them sit, and they can eventually damage your home. 

They’re most common in the Northern U.S. and other areas of the world with heavy snowfall. 

They act like actual dams because they’re large, solid structures that keep water from flowing through them. 

Ideally, your home was built with the threat of ice dams in mind, but this isn’t always the case. If you’ve had ice dams in the past — or are concerned that they might accumulate — then you need to take as many steps as possible to ensure that your house is safe before the next winter begins. 

Measures for ice dam prevention include: 

  • Thoroughly cleaning your gutters and downspouts. Remove leaves, sticks, and any other debris whenever they accumulate. Be most thorough in the times before snowfall becomes heavy in your area. This will help melting snow flow through your gutters rather than accumulating on your roof. 
  • Keeping as much snow off of your roof as possible. In many cases, there’s little you can do once snow starts to fall — but there are still measures you can take. You can buy devices with very long handles that are called roof rakes. These let you remove snow from the roof while you remain on the ground. Keep in mind, though, that these devices can also harm your roofing.  
  • Removing icicles from your gutters. Don’t let these accumulate, or they’ll damage your gutters and add to the melting snow and dams. 

You also may need to look at making sure that your roof and attic have the best insulation and structural setup for preventing ice dams. These changes can be expensive, though, and are best made if ice dams are a severe or recurring problem for your home. 

General recommendations for your attic and roof include: 

  • Internal insulation with an R-value of at least 30 — but 38 is preferable
  • Proper airflow and ventilation near the roof to keep the attic air colder
  • Sealing off all airflow to the attic so the warmth from the house never reaches the attic

Professionals usually don’t recommend installing a heating cable to continually melt the ice. These are expensive to operate and will damage your roof over time. 

Keep in mind that if you successfully prevent ice dams by changing the structure of your house, then more snow can accumulate instead of melting off. Your roof will need to be able to hold the weight of additional snow throughout the winter. 

Make sure that your roof is up to code and able to handle these changes and the additional pileup of snow, or it will collapse — causing even more damage than the ice dam. 

Ice dams are created when the snow on your roof goes through a series of warming and cooling cycles. A warm day can start to melt snow that’s been building up all winter. Then, it becomes cold enough at night for the melted ice to re-freeze. When this happens over and over again — for at least several days in a row — then an ice dam can form. 

The weather isn’t actually the most common cause of an ice dam, though — many times, it just helps it along. Usually, the problem is a heat source within your house. These can include poor attic insulation, exhaust systems from your kitchen or bathroom, or excess heat from your chimney.  

Ice dams tend to form at the edges of roofs and — once formed — keep fresh melt from falling to the ground. This is because the tops of roofs tend to be warmer than the edges. The top gets more heat from the attic beneath it, so ice will melt faster there. Then, this freshwater becomes caught in the colder area that’s further down on the roof. 

Meltwater can ooze between and under your shingles, only to become trapped and cause damage when it freezes again. These cycles of melting and freezing can cause large, destructive problems if you ignore them or don’t realize that they exist. 

Eventually, water can get through your damaged roof and into your house. It can even leak down to lower floors if left unattended for too long. 

Your house is at the greatest risk near the end of the snowy season — when warm spring days begin to appear. The ice dams can build up all winter long, though, so keep an eye out for them at all times. If you notice one beginning to form, remove it or try to keep it from getting any bigger.    

The main source of damage from an ice dam is the water. When it gets into your home — particularly for an extended period of time — it can cause all manner of problems. Some of these include: 

  • Weakening and harming your ceilings
  • Weakening and harming your walls
  • Soaking and harming any objects you have stored in your attic — or lower rooms if the water leaks that far
  • Ruining your insulation
  • Facilitating mold and mildew growth in your attic, walls, and any other affected areas — this can lead to respiratory problems

If an ice dam has already formed on your roof, you need to remove or shrink it as soon as possible to prevent damage. Even poking holes into the chunk of ice will help more water move past it. 

Keep in mind, though, that removing the ice dam too hastily can be dangerous to both you and your roof. Always take as many safety precautions as possible before working on a snowy, ice-covered roof. 

Some techniques that you can try include: 

  • Hosing down the ice dam with warm water — this will work best on a warmer spring day
  • Physically chopping at the ice if you can reach it
  • Removing the ice and snow with roof rakes
  • Calling a roofing professional to enact the removal for you — they will have the professional knowledge necessary to assess your particular dam.