Roofs Peeling Due to Snow

How Ice Dams Form

• Ice dam formation is a combination of winter weather, the water cycle, roof construction and poor insulation. Snow on the roof melts from heated air escaping from a poorly insulated and inadequately ventilated attic. The melted snow slowly drifts downward toward the overhanging roof eaves. Dangling over this cooler section of the roof, the water refreezes, causing those magnificent but malignant icicles characteristic of ice dam formation. As it develops, the ice works it way under the roof shingles, weakening the shingles and forcing them up from the roof deck. In extremely severe and extended cases, the roof deck itself may develop rot, or the wooden deck may warp and dislodge from the roof rafters.

Damage

• Dislodged and peeling roof shingles allow water to infiltrate the attic and interior cavities of the building. Water damage may be slight or severe, causing such problems as water stains, peeling paint, compressed insulation, wood rot, wall damage and mold. Compressed insulation aggravates the damage, as wet and compacted insulation suffers reduced efficiency and allows even more heat loss.

Immediate Solutions

• The roof rake is a specially designed tool to remove snow from the roof. A push broom or lightweight shovel can remove snow, but these tools may damage roof flashing or already weakened roof shingles. For temporary relief for existing ice dams, a homeowner can create a channel in the ice to direct melting snow off the roof. Spray warm water from a hose onto the ice dam, starting at the base of the dam at the eaves and work upward toward the top of the dam.

Prevention

• To prevent ice dams, attics must be properly insulated, adequately ventilated and sealed from leaks of warm air from the heated living spaces below. The goal is to maintain a cool attic and roof deck to prevent the snow from melting on the roof. The U.S. Environmental Protection Agency has issued recommended levels of attic insulation, urging homeowners in the northernmost U.S. states to insulate attics with insulation with an R-value of 49 to 60. Most municipal and state building codes further regulate insulation R-value for the prevention of ice dams according to localized average climate conditions. The attic must be sealed from air seeping from the living spaces, with careful attention to sealing ducts, recessed lights and around chimneys.