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Ice dam basics: How to prevent them and avoid a lot of costly water damage

You don’t want them this winter.

You don’t want them this winter. John Tlumacki / Globe Staff

When it snows, you’re going to need to make sure your house is prepared so you don’t end up going through spring doing repair after repair.

One way to do that is to make sure that you don’t get ice dams this year. We talked to Ben Weil, extension professor of building energy at the University of Massachusetts, about how to prevent ice dams and what to do if you get one.

Here’s what you need to know.

What is an ice dam?

“An ice dam happens when there is snow on a roof and there is some differential heating on the roof,’’ Weil said. “Usually the heat is coming from inside, and it melts the snow and the liquid runs down the roof toward the eve where there is no longer enough heat and then the water refreezes.’’


This leads to icicles coming off your roof, which – though they look really cool – can cause a lot of damage.

How does it happen?

Weil said there are two ways for the snow to melt, the first way being through heat loss from the house.

Dmitry Lipinskiy uses steam to break up icicles on a Carlisle home last winter. He owns Icedam Liquidators, a Minnesota-based company, which drove a crew to the Boston area for a couple of weeks to help people clear their roofs and clear out their ice dams. – Joanne Rathe / The Boston Globe

“The temperature from the indoor air is like 70 degrees and it comes in contact with the roof deck’’ if there is a leak in the house, Weil said. “That’s why often you can look at roofs and see the pattern of air leakage showing up in the snow.’’

The second way is through letting heavy snow pile up on your roof.

“Like the Eskimos knew, snow is not a terrible insulator,’’ Weil said. “If you pile up two feet of snow, you have more insulation than by code for a wall.’’

The snow closer to the roof is going to be closer to the inside temperature because of the snow’s insulation. Weil said the only way to counteract this is to have more insulation in the attic.

So what’s the big deal? Icicles are cool.


Well they do look cool, but they can cause all sorts of problems. As The Boston Globe reports, once the icicles are formed from the melting and refreezing, they can block other water still on the roof from dripping off. The Globe writes, “The draining water hits the ice dam, backs up under the roof shingles, finds cracks and openings in the roofing, and eventually manifests itself as an interior water leak.’’

Construction workers try to fix a home with serious ice dam damage last winter. – Suzanne Kreiter / Globe staff/File

Weil said that just last winter (which we know was particularly bad) he saw many people that needed to have their entire drywall replaced on the second floor or needed their entire electrical system to be redone.

“We are talking lots and lots of money,’’ Weil said.

How can you prevent this from happening?

“The most important thing is preventing air leakage from inside the house from anywhere into the roof system,’’ Weil said. Before it is too late and winter is upon us, you should get your roof checked to see if there are leaks – a group like MassSave could help you with that.

Or, if you go outside and look at your roof when it has frost on it, take a picture and look where there might be strange lines where there isn’t frost. Weil says, “something is causing the frost to melt and that’s an indication of where the snow will melt.’’


A second thing you can do is to get more insulation in the attic. He said this is pretty easy if you have a flat attic and more difficult if you have a cathedral ceiling.

“A third strategy, NOT of equal value,’’ Weil emphasizes, “is proper roof venting. It makes it so that if you have enough outside air travelling up the underside of a roof deck the temperature of either side of a snow roof assembly will be what the outside temperature is and you won’t have melting unless it is a warm day.’’

This will make your problems worse, however, if you haven’t already blocked air leakage nor proper insulation.

How can you fix the problem if you already have it?

“There are a number of solutions that are really Band-Aids to an ice dam problem,’’ Weil said. “Very commonly all over the Northeast you see metal edging, the bottom two feet of a eve has metal roofing. The idea is that the snow will slide off, and often times it doesn’t. The metal can help but it’s not treating the problem.’’

Ice dam in Newton, Massachusetts in Feb. 2015. – Heather Hopp-Bruce/Globe staff

The only thing that is worse than this to Weil are heater strips that turn on when the temperature gets blow a certain number, which melts the snow on the roof.

“They might help get you through a winter but is not a solution,’’ Weil said.


In conclusion

Make sure you home doesn’t have air leaks and make sure you have the proper insulation and keep an eye on your roof throughout the winter months.

“Energy is relatively cheap so it is a hard sell to get people to air seal and insulate as an energy saving tool, but as a maintenance cost avoidance budget this is one place where you don’t have to pay for it with energy savings you can pay for it for avoiding ice dams.’’

Related: Here are the 50 safest towns in Mass.

All 50 of the safest towns in Massachusetts

SafeWise, a home security and safety company, ranked the 50 safest cities in the Bay State, based on the most recent FBI crime stats from 2013. The ranking includes cities with a population over 8,000. According to SafeWise, 49 out of the 50 cities on the list reported no murders during 2013. See if your town made the list, and learn wha different cities are doing to keep residents safe and improve quality of life. Flickr Creative Commons / Massachusetts Office of Travel & Tourism

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50. Longmeadow — Violent Crimes per 1,000: 0.88. Property Crimes per 1,000: 9.84. The townu2019s Ride-Along program helps residents understand what police officers do to protect their community. (Photo: Wikimedia Commons / Faolin42) Wikimedia Commons / Faolin42

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49. Dudley — Violent Crimes per 1,000: 2.92. Property Crimes per 1,000: 7.74. SafeWise praises the historic town for having a police department that actively uses its Facebook page to send out alerts. (Photo: Wikimedia Commons / Magicpiano) Wikimedia Commons / Magicpiano

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48. Pembroke — Violent Crimes per 1,000: 1.82. Property Crimes per 1,000: 8.81. This community recently received a federal grant to fund a brand new Fire Alarm Dispatch Center. (Photo: David L. Ryan/Globe Staff) David L. Ryan/Globe Staff

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47. Stoneham — Violent Crimes per 1,000: 0.50. Property Crimes per 1,000: 9.97. SafeWise points out the active Animal Control in Stoneham that also looks out for potential wild animal attacts against humans. (Photo: Jonathan Wiggs/Globe Staff) Jonathan Wiggs/Globe Staff

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46. Belmont — Violent Crimes per 1,000: 0.94. Property Crimes per 1,000: 9.48. The Crime Prevention through Environmental Design (CPTED) program in this Boston suburb is an initiative to create a safe community through the design of the physical environment, according to SafeWise. (Photo: Wikimedia Commons / Daderot) Wikimedia Commons / Daderot

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45. Concord — Violent Crimes per 1,000: 0.87. Property Crimes per 1,000: 9.46. SafeWise boasts that Concord has a variety of programs to help the community, such as an active D.A.R.E. program. (Photo: Dina Rudick/Globe Staff) Dina Rudick/Globe Staff

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44. Melrose — Violent Crimes per 1,000: 0.75. Property Crimes per 1,000: 9.47. The Melrose Alliance Against Violence is a helpful part of this Victorian community, as it helps bring peace. (Photo: Jonathan Wiggs/Globe Staff) Jonathan Wiggs/Globe Staff

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43. Charlton — Violent Crimes per 1,000: 1.66. Property Crimes per 1,000: 8.56. SafeWise points out the quick response of the fire department, especially during a 2012 fire at the historic Charlton Woolen Mill. (Photo: Wikimedia Commons / Faolin42) Wikimedia Commons / Faolin42

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42. Hanson — Violent Crimes per 1,000: 1.83. Property Crimes per 1,000: 8.31. The town is home to Ocean Sprayu2019s original cranberry bog and has a police program, TRIAD, which makes sure the elderly community is looked after. (Photo: Barry Chin/Globe Staff) Barry Chin/Globe Staff

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41. Newton — Violent Crimes per 1,000: 0.85. Property Crimes per 1,000: 9.29. SafeWise notes the Boston suburbu2019s Community Service Bureau, which assists law enforcement and provides many other services. (Photo: Bill Polo/Globe Staff) Polo, Bill Globe Staff

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40. Andover — Violent Crimes per 1,000: 0.57. Property Crimes per 1,000: 9.09. The Andover Police Department adds extra town security by having an officer who is solely dedicated to patrol the town square. (Photo: Pat Greenhouse/Globe Staff) Pat Greenhouse/Globe Staff

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39. Ipswich — Violent Crimes per 1,000: 0.72. Property Crimes per 1,000: 8.90. SafeWise notes the Ipswich Emergency Management Agency, which provides a variety of programs to help citizens respond to emergencies. (Photo: Jonathan Wiggs / Globe Staff) WIGGS, Jonathan GLOBE STAFF STAF

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38. North Reading — Violent Crimes per 1,000: 0.77. Property Crimes per 1,000: 8.69. The Community Impact Team in North Reading is involved in helping make sure the community is safe and drug free. (Photo: Wikimedia Commons / Faolin42) Wikimedia Commons / Faolin42

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37. Rutland — Violent Crimes per 1,000: 3.02. Property Crimes per 1,000: 6.28. SafeWise notes the communityu2019s u201cCall Firefightersu2019u2019 or a group of volunteers who work on weekends and evenings to learn how to help people in need. (Photo: Wikimedia Commons / Faolin42) Wikimedia Commons / Faolin42

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36. Winchester — Violent Crimes per 1,000: 0.45. Property Crimes per 1,000: 8.78. SafeWise notes that Winchester is eight miles from Boston and has a Computer Crime Unit in its police department. (Photo: Mark Lorenz for the Boston Globe)

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35. Cohasset — Violent Crimes per 1,000: 1.06. Property Crimes per 1,000: 8.16. The coastal town can boast the Cohasset Working Dog Foundation, which provides service animals to those in need. (Photo: David L. Ryan/Globe Staff) David L. Ryan/Globe Staff

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34. Middleton — Violent Crimes per 1,000: 1.17. Property Crimes per 1,000: 7.98. SafeWise commends the townu2019s School Resource Officer program, which protects schools and teaches kids safety. (Photo: David Kamerman / Globe Staff) KAMERMAN, David GLOBE STAFF

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33. Acushnet — Violent Crimes per 1,000: 1.83. Property Crimes per 1,000: 7.14. This town with agricultural roots uses the Connect-CTY System for emergency information delivery. (Photo: Wikimedia Commons / Faolin42) Wikimedia Commons / Faolin42

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32. Westwood — Violent Crimes per 1,000: 1.34. Property Crimes per 1,000: 7.47. According to SafeWise, Westwood police and fire departments have their radio scanners available for people to monitor online. (Photo: Joanne Rathe/Globe Staff) Joanne Rathe/Globe Staff

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31. Westborough — Violent Crimes per 1,000: 0.75. Property Crimes per 1,000: 8.02. The police department in Westborough has an i-SAFE program on Internet safety education. (Photo: Lane Turner/Globe Staff) Lane Turner / Globe Staff

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30. Scituate — Violent Crimes per 1,000: 1.31. Property Crimes per 1,000: 7.40. SPaN, or the Scituate Police and Neighbors program is what helps keep residences safe in this town on the water. (Photo: Jonathan Wiggs/Globe Staff) Jonathan Wiggs/Globe Staff

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29. Marblehead — Violent Crimes per 1,000: 0.84. Property Crimes per 1,000: 7.86. The harbor town has a variety of safety precautions that SafeWise mentions, such as the MyPD App emergency notification system. (Photo: Wendy Maeda/Globe Staff) Wendy Maeda/Globe Staff

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28. Medway — Violent Crimes per 1,000: 0.07. Property Crimes per 1,000: 8.58. SafeWise notes that Medwayu2019s police department has a Summer Traffic Enforcement program to teach motorists to slow down in school zones. (Photo: Landers, Tom Globe Staff) Landers, Tom Globe Staff

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27. Groton — Violent Crimes per 1,000: 0.71. Property Crimes per 1,000: 7.70. The police department in this community has a confidential tip line for residents to report any suspicious activity. (Photo: Wikimedia Commons / Daderot) Wikimedia Commons / Daderot

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26. Acton — Violent Crimes per 1,000: 0.34. Property Crimes per 1,000: 7.78. Just last year, all school buses for the town had security cameras added inside. Jon Chase for the Boston Globe

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25. Georgetown — Violent Crimes per 1,000: 0.35. Property Crimes per 1,000: 7.56. SafeWise praised the peaceful townu2019s drug drop-off receptacle, which helps keep dangerous medicines out of landfils and water supplies. Jim Davis/Globe Staff

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24. Douglas — Violent Crimes per 1,000: 1.15. Property Crimes per 1,000: 6.72. The Blackstone River Valley townu2019s police department uses, which makes resolving car accidents easier. (Photo: Wikimedia Commons / Faolin42) Wikimedia Commons / Faolin42

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23. Grafton — Violent Crimes per 1,000: 1.20. Property Crimes per 1,000: 6.65. The town is known for its historic mill sites, but SafeWise pointed out the police departmentu2019s SafeLink service, which is a domestic violence hotline. (Photo: George Rizer for the Globe) gerge rizer

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22. Reading — Violent Crimes per 1,000: 0.39. Property Crimes per 1,000: 7.24. The town has services like Highway Safety Mobilizations, which enforces a zero-tolerance policy for drinking and driving. (Photo: Jim Davis/Globe Staff) Jim Davis/Globe Staff

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21. Lexington — Violent Crimes per 1,000: 0.52. Property Crimes per 1,000: 7.10. SafeWise noted that though this town is known for its historic American Revolution battle, it has programs like the School Threat Assessment and Response System (STARS) to help schools and law enforcement prepare for violence. (Photo: Michael Dwyer / AP) Michael Dwyer

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20. Shrewsbury — Violent Crimes per 1,000: 0.16. Property Crimes per 1,000: 7.40. Women in the community have access to a Rape Aggression Defense (R.A.D.) program. (Photo: Joanne Rathe/Globe Staff) Joanne Rathe/Globe Staff

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19. Wellesley — Violent Crimes per 1,000: 0.51. Property Crimes per 1,000: 6.95. SafeWise attributes some of Wellesleyu2019s low property crime rate to the 24/7 commercial and residential property checks around town. (Photo: Jonathan Wiggs/Globe Staff) Jonathan Wiggs/Globe Staff

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18. Hamilton — Violent Crimes per 1,000: 0.36. Property Crimes per 1,000: 6.15. SafeWise praised this family-friendly community for having a Child Passenger Safety (CPS) Program to teach parents about proper safety seat usage. Pat Greenhouse/Globe Staff

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17. Holliston — Violent Crimes per 1,000: 0.98. Property Crimes per 1,000: 5.28. SafeWise credits Holliston with expanding its social services, including Holliston Youth and Family Services, to address its growing population. (Photo: cmh2315fl/Flickr) cmh2315fl/Flickr

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16. Hopkinton — Violent Crimes per 1,000: 0.19. Property Crimes per 1,000: 5.92. Every year, runners flock to Hopkinton as the Boston Marathon gets started. SafeWise also praised Hopkinton for its efforts to protect residentsu2019 health and wellness, including anonymous mental health screenings. (Photo: Bill Greene/The Boston Globe) The Boston Globe

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15. Southborough — Violent Crimes per 1,000: 0.20. Property Crimes per 1,000: 5.85. Local law enforcement in the town just created a Internet Transaction Safety Zone in a parking lot to help prevent citizens from being the victim of a criminal act over the internet. (Photo: Globe Photo/ Laurie Swope) Globe Photo/ Laurie Swope

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14. Holden — Violent Crimes per 1,000: 0.45. Property Crimes per 1,000: 5.40. SafeWise highlighted Holdenu2019s conservation and public safety awareness efforts, including the u201cHolden Fire Explorer Programu2019u2019 that educates future firefighters. (Photo: Doug Kerr/Flickr) Doug Kerr/Flickr

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13. Westford — Violent Crimes per 1,000: 0.60. Property Crimes per 1,000: 5.21. This Lowell suburb has instituted community safety initiatives that include a drop box for prescription drugs and bicycle and pedestrian safety programs. (Photo: Doug Kerr/Flickr) Doug Kerr/Flickr

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12. Bedford — Violent Crimes per 1,000: 0.43. Property Crimes per 1,000: 5.30. Bedford is located near Concord and Lexington. SafeWise praised the town for its community offerings, including the Bedford Center for the Arts. (Photo: John Blanding/Globe Staff) John Blanding/The Boston Globe

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11. Weston — Violent Crimes per 1,000: 0.25. Property Crimes per 1,000: 5.46. Weston, the Commonwealthu2019s wealthiest community, was praised by SafeWise for its commitment to reduce energy consumption by 20 percent over five years. (Photo: Justin Saglio for The Boston Globe) Justin Saglio for The Boston Globe

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10. Medfield — Violent Crimes per 1,000: 0.97. Property Crimes per 1,000: 4.71. Medfield won accolades from SafeWise for the u201cMedfield Youth Outreach Program,u2019u2019 an initiative that provides free counseling and crisis intervention to families in need. (Photo: The Boston Globe) The Boston Globe

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9. Franklin — Violent Crimes per 1,000: 0.21. Property Crimes per 1,000: 5.24. Franklinu2019s library still has books donated by founding father Benjamin Franklin, the townu2019s namesake. SafeWise highlighted the town councilu2019s initiatives to educate and support senior citizens. (Photo: cmh2315fl/Flickr) cmh2315fl/Flickr

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8. Sudbury — Violent Crimes per 1,000: 0.00. Property Crimes per 1,000: 5.13. SafeWise highlighted Sudburyu2019s Teen Center as a place where young people can enjoy supervised recreational activities. (Photo: Doug Kerr/Flickr) Doug Kerr/Flickr

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7. Norton — Violent Crimes per 1,000: 0.41. Property Crimes per 1,000: 4.63. As host of the Deutsche Bank Championship Golf Tournament, Norton has experience in addressing public safety. The community has a program to teach residents about disaster response preparedness, including basic search and rescue techniques. Doug Kerr/Flickr

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6. Boxford — Violent Crimes per 1,000: 0.49. Property Crimes per 1,000: 4.17. SafeWise noted that the scenic town has free security checks and other safety services provided by the police department. (Photo: Brian Snyder / Reuters) BRIAN SNYDER

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5. Sharon — Violent Crimes per 1,000: 0.05. Property Crimes per 1,000: 4.23. Home to scenic trails and settings including Lake Massapoag, Sharon was parised for its conservation efforts, which pair with the townu2019s safety and community planning efforts. (Photo: John Tlumacki) John Tlumacki /The Boston Globe

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4. Duxbury — Violent Crimes per 1,000: 0.13. Property Crimes per 1,000: 3.87. Duxbury is a coastal community within commuting distance of Boston. According to SafeWise, Duxbury also saw a decrease in violent crime and property crime last year. (Photo: Dina Rudick/Globe Staff) Dina Rudick/Globe Staff

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3. Clinton — Violent Crimes per 1,000: 0.72. Property Crimes per 1,000: 2.91. In addition to hosting the oldest actively used baseball field in the world, Clinton also offers early childhood education, adult education courses, and English language courses for its residents. (Photo: Doug Kerr/Flickr) Doug Kerr/Flickr

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2. Norfolk — Violent Crimes per 1,000: 0.00. Property Crimes per 1,000: 3.51. Norfolk, which once housed figures from the Revolutionary War including George Washington, reported no violent crimes in 2013. Doug Kerr/Flickr

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1. Wayland — Violent Crimes per 1,000: 0.37. Property Crimes per 1,000: 3.13. Wayland, home to the Commonwealthu2019s first public library, earned its way onto SafeWiseu2019s rankings with its free fire education programs, including a preschool program and a babysitting course. (Photo: Jonathan Wiggs/Globe Staff) Jonathan Wiggs/Globe Staff

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