Snow on roofs, giant icicles, and ice dams
Rows of long, thick icicles hanging from your gutters look pretty on a postcard, but they are usually a warning sign of an 'ice dam' that can force melting water backward under your roof shingles and into your walls.
If you only do three things
- Never stand underneath large icicles or knock them down while standing directly below them—falling icicles weigh tens of pounds and cause severe injuries.
- Use a long-handled aluminum 'roof rake' while standing safely on the ground to pull snow off the bottom 3 to 4 feet of your roof edge after a storm.
- Never climb a ladder onto an icy roof or attack roof ice with a hammer, axe, or rock salt (which ruins shingles and gutters).
What an ice dam is and why it makes ceilings leak
When heat escapes from your living space into your attic, it warms the upper part of your roof. Snow on the upper roof melts and trickles down underneath the snow blanket until it reaches the cold overhang (eaves) at the edge of the roof.
Because the overhang sits past the warm walls of the house, that water refreezes into a thick ridge of solid ice along the gutter. New meltwater pools behind that ridge of ice, backs up underneath the shingles, and drips through your ceiling drywall.
Emergency fix if an ice dam is leaking into your house
- Pull loose snow off the lower 3–4 feet of the roof edge from the ground using a telescoping roof rake.
- Take the leg of an old pair of pantyhose or a long tube sock, fill it with Calcium Chloride ice melt (NOT rock salt), tie the end, and lay it vertically across the ice dam so it hangs slightly over the gutter. It will melt a narrow channel through the ice dam so trapped water can drain off the roof.
- Place a box fan in the attic aimed at the underside of the leaking roof decking to freeze the seepage temporarily.
Warning signs that snow on your roof is too heavy
Most pitched residential roofs can hold 2 to 4 feet of dry snow, but wet snow or rain-soaked snow weighs 3 to 4 times more. Watch for these warning signs on flat roofs, porch roofs, and mobile homes:
- Interior doors or windows suddenly sticking or refusing to close squarely (a sign the house frame is flexing under weight).
- New cracks appearing in drywall above doorframes or along ceilings.
- Loud popping, cracking, or groaning sounds from the ceiling rafters.
Related guides
- Protecting your home and pipes: Complete home winter readiness guide.
- Storm approaching 48-hour checklist: How to prepare your home before a major snowstorm.