Ice Damming – What you should know

Hello all. We hope everyone is staying warm & safe during this unusually snow/icy winter we are having here in east Tennessee.

We have been receiving a lot of calls about roof leaks that are occurring due to ice dams.  Ice dams are more familiar to people who live in northern states where winters are more harsh and snow/ice precipitation is normally expected. Although not completely unheard of, this is not typically an issue that affects most of us in the southern United States. Since this concept may be new to some people here in Tennessee, here is some educational information on ice dams:

What is an ice dam?   A formation of ice on the lower roof line that continues to grow up and over the side of the roof line forming large and potentially dangerous icicles.

What causes an ice dam?  An ice dam can form when the attic space is not properly insulated and ventilated. This allows heat above freezing (32 degrees) to rise and melt snow on the top of a roof. The parts of the roof that are furthest away from the heat escaping are at or below the freezing point. This would typically be where the gutters, eaves, soffit and fascia are located. The snow at the top of the roof melts and runs down the roof line toward the lower shingles where it will freeze and become ice. As the snow or ice continues to melt, run down and refreeze, this ice will build up and continue to find places to expand. It can force its way under shingles and up the roof line and overflow past the gutters forming large icicles.

Will an ice dam cause damage?  As the dam continues to grow, the water/ice can push underneath the shingles and penetrate (soak through) the decking on a roof. If the penetration is heavy, it will result in a visible leak on the ceiling or running down the walls, etc. Anytime water enters a home the damage can be substantial.

Can an ice dam be prevented?  There are preventative measures that can be taken to reduce the likely hood that an ice dam will form. Properly insulating & ventilating the attic space is a must. Escaping heat on the roof causes the melting of the ice/snow that will result in an ice dam. Another preventative measure would be to ensure a preventative product such as “ice and water shield” is used during the installation of new roofing. (Some homeowners or roofers may choose the less expensive option of using felt when installing a new roof.)  Ice and water shield must be installed on roof in the Northern states by code to prevent damage from wind-driven rains and ice dams, but is not necessarily code in most southern states. To verify current building codes, please check with your local authorities. Also, when installing a new roof, ensure the proper flashing techniques are used around vulnerable areas such as penetrations in the roof and roof to wall areas.

How can the damage be repaired? Each ice damming occurrence is different & unique. A professional should assess the situation and present a resolution.

Below is an illustration courtesy of the popular television show This Old House to help visualize an ice dam.

Ice Dam
Ice Dam

If you live in the greater Knoxville area and need a professional to assess your roofing conditions, give us a call at 865-771-4085. We can assist with restoring the exterior and interior of your home.