Attic Condensation & Ice Dam Leaks

Preventing Ice Dam Leaks

Attic condensation and ice damming are related. Both can be caused by warm, moist air leaving the house and entering the attic. Attics will be in good shape if there are no holes, air leaks, or bypasses from the house to the attic and there is sufficient insulation to keep house heat from escaping. If you can ensure good air sealing and insulation, the attic will remain cool and dry, as if it were outside. For example, it is rare to see moisture problems or ice damming on the roof of a detached garage or unheated barn.

Formation Of An Ice Dam

Where to look for leaks

  • around plumbing stacks or plumbing walls
  • chimneys through the attic
  • any light fixtures from the ceiling below
  • electric wiring
  • ducting for fans or heating systems
  • perimeter walls
  • partition walls
  • party walls
  • above pocket doors
  • above lowered ceilings
  • where the side of a cathedral ceiling meets an open attic
  • split level discontinuities
  • where additions meet an older section of the house
  • above rounded corners or staircases
  • balloon frame walls

Prevent Ice Dams With Ventilation

Attic Venting

If you have properly sealed the attic you should not need more attic ventilation. Attic ventilation is overrated. In winter, the cold outside air cannot hold much humidity or carry moisture away from the attic. In summer, attic temperatures are more affected by the sun and shingle color than by the amount of ventilation.

Ice Damming

Ice dams are the large mass of ice that collects on the lower edge of the roof or in the gutters. As more melting snow (or rain) runs down the roof, it meets this mass of ice and backs up, sometimes under the shingles and into the attic or the house.

Ice damming usually occurs with a significant depth of snow on the roof. If the attic temperature is above freezing, it warms the roof sheathing which melts the snow lying on the shingles. This water runs down the roof until it meets the roof overhang, which is not warmed by the attic and will be at the temperature of the surrounding air. If the air and the overhang are below freezing, then the water will freeze on the roof surface and start the ice dam.

The balance between removing ice and damaging the roof

Thick ice is hard to remove. You must decide if trying to remove it will cause more damage than leaving it on the roof. Tools, such as hammers, shovels, scrapers, chain saws, and devices such as shoes with ice spikes can damage roofing materials or the structure below. Chemical de-icers can discolor shingles, break down membranes and corrode flashings and drains. De-icers can also damage plants on the ground.

Has your roof been damaged by a winter storm and you’re now looking for a Minnesota roofing contractor to fix it?

If damage has occurred and ice must be removed, hiring professionals that use steamers is strongly recommended.

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