We are fortunate to live in a state where we enjoy all four seasons, but with the winter season, ice damning is a possibility on all shingled roofs. Unfortunately, ice damning is impossible to eliminate, but it can be reduced by following a couple of simple steps when installing your new roof.
The first preventative measure is to make sure your roofing contractor installs Ice & Water Shield to all heated eaves. Michigan building code calls for Ice & Water shield to be a minimum of 2 feet inside your heated wall, not 2 feet from the edge of the roof. At Horizon Roofing we install a minimum of 6 feet of ice & water shield on all eaves, around all chimneys, and where all step flashing is installed.
Another way to deter the build-up of ice on your roof is to install a balanced air system, which includes a sufficient amount of exhaust vents (Box or Ridge) which is also accompanied by an equal amount of air intake (Vented edge or soffit). By creating an intake system, you allow for cool dry air to be introduced into your warm humid attic and because cold air weighs more than warm air, it pushes the warm air down producing air movement. That, in turn, reduces moisture produced where the attic’s warm air collides with the cold outside air temps at the roofline, reducing the possibility of ice damns.
The final step we suggest to help reduce ice damns is installing new or making sure your existing insulation is at the D.O.E. suggested R-value. Southeastern Michigan is located in Zone 5 with a suggested Insulation R-value of 49 or roughly 14-16 inches.