healthy house institute

4 Free HHI Books:

Creating a Healthy Household, The Healthy House Answer Book, Healthy Home Building, The Healthy House 4th Edition
Your email will only be used as described in our Privacy Policy

Follow us on Twitter



Proud Supporter of:




Keys to Preventing Ice Dams

By HHI Staff

When a roof is properly vented, the shingles will often be close to the outdoor temperature, so winter snow won’t melt on the roof until the outdoor air temperature rises above freezing.


article continues below ↓

We do not strictly control Google ad content. If you believe any Google ad is inappropriate, please email us directly here.

However, ice damming—which can lead to mold, mildew, or rot—can sometimes occur with improperly vented roofs in the winter. If the attic insulation is packed tightly at the eaves, heat from the living space slowly moves through the insulation and warms the roof deck slightly. The snow directly over the warm part of the roof melts and runs down the slope. When it hits the part of the roof above the overhang (which is colder) it refreezes, forming an ice dam on top of the roof. This can take place under a blanket of snow, so you may not see it, but the dam can allow melted snow to back up under the shingles, and leak into the attic or living space. Sometimes, ice damming is accompanied by large icicles hanging down from the eaves.
The solution is to insert special baffles between the insulation and the roof deck. This allows air to circulate under the deck, keeping it cold and, thus, preventing the heat from the living space from melting the snow. When baffles are in place, heat from the living space still slowly enters the attic, but it dissipates into the attic air, and is carried out through the vents.


From: The Healthy House, 4th edition, published by The Healthy House Institute.  


For more information about proper ventilation, visit the Home Ventilating Institute (HVI).





HHI Error Correction Policy

HHI is committed to accuracy of content and correcting information that is incomplete or inaccurate. With our broad scope of coverage of healthful indoor environments, and desire to rapidly publish info to benefit the community, mistakes are inevitable. HHI has established an error correction policy to welcome corrections or enhancements to our information. Please help us improve the quality of our content by contacting with corrections or suggestions for improvement. Each contact will receive a respectful reply.

The Healthy House Institute (HHI), a for-profit educational LLC, provides the information on as a free service to the public. The intent is to disseminate accurate, verified and science-based information on creating healthy home environments.


While an effort is made to ensure the quality of the content and credibility of sources listed on this site, HHI provides no warranty - expressed or implied - and assumes no legal liability for the accuracy, completeness, or usefulness of any information, product or process disclosed on or in conjunction with the site. The views and opinions of the authors or originators expressed herein do not necessarily state or reflect those of HHI: its principals, executives, Board members, advisors or affiliates.

Keys to Preventing Ice Dams:  Created on September 25th, 2013.  Last Modified on January 21st, 2014


We do not strictly control Google ad content. If you believe any Google ad is inappropriate, please email us directly here.



Information provided by The Healthy House Institute is designed to support, not to replace the relationship between patient/physician or other qualified healthcare provider.

Education Partners



Popular Topics: Air Cleaners & Air Purifiers | Allergies & Asthma | Energy Efficiency & Energy Savings | Healthy Homes | Green Building
Green Cleaning | Green Homes | Green Living | Green Remodeling | Indoor Air Quality | Water Filters | Water Quality

© 2006-2017 The Healthy House Institute, LLC.


About The Healthy House Institute | Contact HHI | HHI News & Media | Linking Resources | Advertising Info | Privacy Policy | Legal Disclaimer


HHI Info