Ice damming occurs when gutters fill with ice from continual freeze - thaw cycles.

As these cycles continue, thawing snow on the roof works its way back up under the shingles by capillary action. The moisture enters the attic area and drips on to the attic-side of the ceiling. Stains begin to form on the room side of the ceiling, usually near a perimeter wall, and if sufficient water accumulates in the attic, the interior of the ceiling could begin to drip and disintegrate.

If the accumulated attic water begins to drip into the room, you may poke a hole in the ceiling with a large nail at the drip point and put a bucket under the opening. Furniture should be moved away from the area below. Poking a hole in the ceiling will localize the draining of the attic and prevent more extensive damage. Nothing can be done to repair the ceiling until all the water is drained from the attic and the gypsum board ceiling dries out.