Why it matters

• In an established suburb like Maple Grove, ice dams are rarely a one time fluke. They usually trace back to the same handful of causes repeating winter after winter in homes that have not had their attic ventilation reassessed since they were built.

• 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 ridges appear at the roof edge. Waiting until spring lets water sit under the shingles all winter, which is when decking rot and interior staining actually happen.

• Before another freeze thaw cycle hits. Minnesota winters rarely deliver just one cold snap, and each additional cycle adds more ice to an existing dam.