2008 into 2009 and 2009 into 2010 were two of those winters that Ice Dams formed on the roofs. Excess snow, ice, and thawing and refreezing helped to create conditions perfect for this harmful effect to the home. 2012 into 2013 looks like another winter for continuing ice problems.
Creating an Ice dam: Snow fall hits the roofing, then melts during warmer periods. Ice forms beneath the snow typically filling the gutters of the home. As snow continues, the buildup continues. If the snow fall is heavy, the thawing and refreezing excessive, the ice beneath works its way up the roof shingles and eventually creeps into the attic area of the building. Warmer temperatures at the soffet area of the home (at the gutters) melts the ice causing water to enter the upper wall and ceiliing location of the interior rooms.
Ice dams can enter the 2nd floor area of a home and leak down the walls into the basement when excessive. Older home with an older roofing system will generally have ice dam issues. A multi-layered roofing system will more than likely not have proper safeguards installed to prevent ice dams, and may in fact have conditions that invite ice dam issues. Newer roofing systems have a safeguard known as Ice guard installed at the areas of the rooifng that require protection. Ice guard is a rubberized layering that is installed on the existing wood of the roof prior to standard felt paper installation. Over this is placed the roofing shingles. Ice guard is installed at the perimeter of the roof and at locations that may be suceptible to leakage, such as valleys, and flashing. Lower pitched roofs may have the entire sheathing area ice guarded.
Improper ventilation of the roof, deficient attic insulation, and areas at the exterior that invite freezing and thawing are conducive to ice dam leakage. A soffet at the exterior aids in keeping proper air flow through the roofing system. A home with minimal or no soffet typically has more issues, such as Ice Dams, than those with soffets.
Other safeguards are heating tape installed at the edge of the roof, above the gutters, and installation of venting and insulation. Ice at the roofing system generally runs down the wall and ends up at floor location. Wall damage can be a problem, as well as potential mold issues.
Photos of recent Ice dams on area homes.
Ice spreading from the gutters down the siding and entering the interior room.
Ice at the siding and windows. Note: No soffet at the gutters.
This Ice Dam leaked into the closet wall and created issues with wet conditions.