A Post Bob did the other day and being that it is snowing like cats and dogs out there right now, I thought I would repost this as it is a concern here in the northeast as the snow continues to pile up today.
At this time of the year the cold weather can do some real damage to your home. One thing in particular are Ice Dams that can form in your gutters. This is a particularly bad thing. Ice Dams can cause sever damage to the interior of a home. I received this information from a home inspection company the other day that we had at one of our sales recently.
I thought it was very insightful and worthy of posting as we are in the middle of a winter storm right now...
Enjoy and keep warm and watch those gutters.
What is an ice dam?
An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow (water) from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation, and other areas.
Courtesy of Foresight Home Inspections
What causes ice dams?
There is a complex interaction among the amount of heat loss from a house, snow cover, and outside temperatures that leads to ice dam formation. For ice dams to form there must be snow on the roof, and, at the same time, higher portions of the roof's outside surface must be above 32° F while lower surfaces are below 32° F. For a portion of the roof to be below 32° F, outside temperatures must also be below 32° F. When we say temperatures above or below 32° F, we are talking about average temperature over sustained periods of time.
The snow on a roof surface that is above 32° F will melt. As water flows down the roof it reaches the portion of the roof that is below 32° F and freezes. Voila!!- an ice dam.
The dam grows as it is fed by the melting snow above it, but it will limit itself to the portions of the roof that are on the average below 32° F. So the water above backs up behind the ice dam and remains a liquid. This water finds cracks and openings in the exterior roof covering and flows into the attic space. From the attic it could flow into exterior walls or through the ceiling insulation and stain the ceiling finish.
What causes different roof surface temperatures?
Since most ice dams form at the edge of the roof, there is obviously a heat source warming the roof elsewhere. This heat is primarily coming from the house. In rare instances solar heat gain may cause these temperature differences.
Heat from the house travels to the roof surface in three ways: conduction, convection, and radiation. Conduction is heat energy traveling through a solid. A good example of this is the heating of a cast iron frying pan. The heat moves from the bottom of the pan to the handle by conduction.
If you put your hand above the frying pan, heat will reach it by the other two methods. The air right above the frying pan is heated and rises. The rising air carries heat/energy to your hand. This is heat transfer by convection. In addition, heat is transferred from the hot pan to your hand by electromagnetic waves and this is called radiation. Another example of radiation is to stand outside on a bright sunny day and feel the heat from the sun. This heat is transferred from the sun to you by radiation.
In a house, heat moves through the ceiling and insulation by conduction through the slanted portion of the ceiling in many homes, there is little space in regions like this fro insulation, so it is important to use insulation's with high R-value per inch to reduce heat loss by conduction.
The top surface of the insulation is warmer than the other surroundings in the attic. Therefore, the air just above the insulation is heated and rises, carrying heat by convection to the roof. The higher temperatures in the insulation's top surface compared to the roof sheathing transfers heat outward by radiation. These two modes of heat transfer can be reduced by adding insulation. This will make the top surface temperature of the insulation closer to surrounding attic temperatures directly affecting convection and radiation from this surface.
I want to thank Foresight Home Inspections for this most informative post. I hope you enjoyed this and learned something.
I know I did.
If you or someone you know is planning a Move or Sale of their home in the near future, call your Bergen County, NJ experts, Lisa & Bob Hammerstein at (201)218-6802 or visit us on our website at www.HammersTeam.com. We'll be able to help you if you're Moving or Selling in any of the towns located in Bergen County New Jersey.
For more Local Information about the Pascack Valley area of Bergen County, New Jersey, call Bob & Lisa at (201)218-6802or visit us online at www.HammersTeam.com.
Your Real Estate Resource for the Bergen County - specializing in the Pascack Valley! 
__________________________________________________________________
Robert & Lisa Hammerstein • Sales Associates • Coldwell Banker • (201)315-8618
• Address • 50 Broadway • Hillsdale, NJ 07642 •
DISCLAIMER: We must disclaim liability for any damages or losses, direct or indirect, that may result from use of, or reliance on, any information contained in this blog, or for the accuracy of comments or opinions expressed by visitors to our blog. The information contained in the articles is deemed reliable but is not guaranteed, and the opinions expressed in these articles are ours.
I had a nasty ice damn last winter in my bathroom. Ruined my ceiling and wall. What a mess!
Thank you for the post. It should be read by all home owners in my area.
Is there any solution that will prevent ice dams from forming? New gutters, insulated roofing, anything?
This was very informative, and something that all homeowners need to know, especially in the northern parts of the country.
Bob and Lisa - thanks for some great information. While I don't have this particualr worry any more, I remember those days all to well. It can be a major hassle. I remember getting up on the roof and cleaning it off and the gutters more times than I can count. Once the ice forms you are in big trouble.
Terrific information for homeowners, especially new ones. Given this winter with record snows, this can be a huge problem.
Jeff
Hi Moni,
That's a bummer! Weather is one of those forces of which we have no control over. Hope this year is kinder to your home.
Hi Gita,
Yes, PA is not far from us so you must suffer the very same in your area. Thanks for stopping by.
Hi William,
The weather sadly doesn't cooperate so keeping an eye on the gutters is the best that any of us can do. Getting up there and chopping off any ice that is forming can be a dangerous proposition so it may be best to keep those gutters as clean as possible in the warm months. Knocking down the icicles that form is a good idea too since they could fall and possibly hurt an unsuspecting individual. Good luck with your ice dam!