01/02/2026
This detailed cross-section reveals one of the most destructive forces a home can face in winter: the Ice Dam. While those giant icicles hanging from the Gutter might look picturesque, the diagram shows the silent damage happening underneath.
Heat escaping from the home melts the Snow on the upper roof. As this water runs down to the colder eaves, it refreezes, forming a solid ridge of ice known as an Ice Dam.
Once the dam is formed, melting snow has nowhere to go. It creates a pool of Trapped Water backing up underneath the Shingles.
The water seeps through the roof deck, dripping onto the pink Insulation (rendering it ineffective).
The water continues downward, soaking the Drywall ceiling (causing stains, sagging, and mold) and even running down into the structural Wall Cavity.
If you see large icicles forming, your roof isn't shedding heat properly! Proper attic insulation and ventilation are key to stopping this cycle.
