Published on January 13th, 2013 | by Henri0
Roof leaks from melting ice dams
Q. About 15 years ago, after a snowstorm, an ice dam formed and melting ice leaked into our livingroom doing considerable damage. We had both layers of roofing removed and, after consulting with the Celotex people who make an ice shield, we had 11 feet of it applied from the eaves up although they had recommended only nine feet.
Last winter, we experienced leakage again in the livingroom. We called the Celotex people again and were advised that the ice shield would not eliminate the ice dams but prevent the problem. We can’t see much difference in the wording. We were advised to shovel the roof when an 8-inch snowfall occurred.
With an ice shield installed, this did not seem reasonable to us. We respect your knowledge and expertise in helping homeowners solve their problems and hope you can help us with ours. Thank you.
A. The Celotex people are right in telling you that an ice shield membrane does not eliminate ice dams but prevents damages from leakage, but they are wrong in advising you to shovel snow off your roof. Not only can this be dangerous to the person who does the shoveling, but it can irreparably damage the shingles and void their warranty.
However, several things may be wrong with the installation of the membrane. It should be installed on clean, bare roof sheathing. The metal drip edge at the eaves must be under the membrane; if not, water can leak under the drip edge and penetrate the house. The contact paper keeping the membrane from sticking to itself must be peeled off as the membrane is unrolled during installation (as elementary as this sounds, I have seen cases where the paper was left on so there is no adhesion to the sheathing). If none of these mistakes was made, the leakage is probably due to water freezing in your gutter and subsequent melting ice being pushed into the house through the joint between the fascia board and the roof sheathing.
To stop this from happening, the gutter should be removed and a piece of metal should be inserted behind the existing drip edge and going all the way up until it hits the drip edge flange under the membrane and roof shingles, thus sealing the opening between the fascia board and the roof sheathing. This metal piece should cover the fascia board at least to the bottom of the gutter. Afterward, the gutter can be put back.by