Leaking During or After Snow Melts on the Roof

Description

• An ice dam forms when melted snow continually refreezes near the roof’s edge. More snow melts, running down until it pools against the developing ice ridge, which blocks it from draining into the gutters or off the eaves. As the water backs up, it leaks through the shingles and into the house, running down the insides of walls, dripping from ceilings and soaking insulation. It causes mold problems and even structural damage in time.

Cause

• Variations in roof temperature cause ice dams. Snow melts on warm areas of the roof, usually near the top, and refreezes where the temperature remains below freezing. These temperature variations are caused by insufficient insulation in the attic allowing heat from the home's interior to rise through the attic space and warm the roof’s upper areas. Gaps around pipes and electrical conduits running into the attic are common heat loss culprits.

Prevention

• Permanent ice dam prevention requires careful insulation in the attic. The attic should be as airtight as possible with adequate insulation depth for the climate. Installing soffit vents or ridge vents allows warm air to harmlessly escape from the attic. Clearing snow from the edges of the roof with a roof rake is a short-term solution. Watch out for power lines and never climb on the roof to remove snow or ice.

Other Leaks

• If you rule out an ice dam as your leaking roof’s cause, it's possible that the roof surface itself is damaged and letting in water. Use the position of the interior leak to estimate the damaged area’ location and inspect that part of the roof for broken or missing shingles. If an asphalt shingle is flapping loose, glue it back down with roofing tar and nail it into place. If a wood or asphalt shingle is damaged, promptly replace it to minimize water infiltration problems.