Why it matters

• Monticello's river corridor location does not directly affect roof-level ice damming the way it affects the river itself, so the underlying causes here are the same attic insulation, ventilation, and air sealing issues found throughout Minnesota.

• Poor attic insulation that lets heat escape and warms the roof deck from underneath.

• Inadequate attic ventilation that keeps the underside of the roof warmer than the outside air.

• Air leaks around recessed lights, attic hatches, vents, and chimneys that let warm household air reach the attic.

• Heavy snowfall followed by freeze thaw cycles which are common through a Minnesota winter.

• Roof design and older or worn roofing materials that let water back up under the shingles once ice has formed.

When it makes sense to act

• As soon as ice forms, regardless of proximity to the river. The river's warm water discharge affects the waterway, not the attic, so there is no local reason to expect an ice dam to resolve on its own.

• Before a freeze thaw cycle repeats on an older Monticello home. Homes further from the newer Chelsea Commons development may carry older attic systems more prone to repeat ice damming.