Why does ice dam damage show up in the ceiling and not on the roof?
Water that gets past the shingles runs along the roof deck, soaks the insulation and drips onto the ceiling below. The roof may look fine from the street. Damage tends to appear on the top-floor ceiling, at the tops of exterior walls and in the attic. Stained plaster, wet insulation and mold are the usual signs.
The roof is often fine until the next thaw, which is part of why the problem repeats. Water finds the same gap in each cold spell, so a stain that dries out in March can return in January.
In an older house, the ceiling under that gap is often plaster. Plaster holds water and then sags, and wet insulation above it keeps the area damp long after the snow has gone. The ceiling water damage page explains what happens to plaster that gets this wet.
Mold can grow on wet insulation and roof framing if it stays damp. The EPA advises drying water-damaged materials within 24 to 48 hours, which is why wet insulation is usually removed and not left to dry slowly.
What can a temporary roof tarp do, and what can it not do?
A tarp covers an opening and slows water while you arrange a roofer. It does not repair shingles, flashing or the roof deck, and it is not a long-term fix. Emergency tarping is part of the work here, but roof repair and roof replacement are not. A roofer handles the permanent repair.
Tarping a snowy or icy roof is not always safe. If the roof is too icy or steep to reach, the crew will say so and focus on protecting the inside until conditions improve.
A tarp has to be fastened properly and tied to a structure that can hold it, so it does not blow off or tear shingles. A badly secured tarp can do more harm than none.
After the tarp, the next steps are a roofer for the repair and the crew for the interior. The two can work in sequence, and keeping the dates in order means the roof is closed before new drywall goes up.
What should you do while snow is still on the roof?
Stay off the roof, protect the room below and call. Put buckets and plastic sheeting under active drips, move belongings and photograph the damage. Do not chip ice with a hammer or axe, since that can tear shingles and invite a fall. Phones are answered around the clock, and a crew goes out as soon as one is free.
Inside, the goal is to slow the damage. Punching a small hole in a bulging ceiling to drain water into a bucket is something a technician does carefully, because the plaster above may be heavy and ready to come down.
Open the attic hatch if you can reach it safely and look at the insulation. If it is wet or matted, tell the crew and the roofer, since it shows where the water entered.
After the thaw, ask a roofer or an insulation contractor about the cause. Fixing the heat leak and the ventilation is what prevents a repeat, and that work is outside what a restoration crew does.
