This is our second winter in our house. For this first time we have ice damming at two places on the roof. We had a slight thaw this past weekend (Feb. 1) and water leaked into our master bedroom ceiling and dripped into the room.

What causes ice damming on roofs? We had insulation blown in to the first and second floor walls of our 1927 home over the summer. Could that have something to do with it? Is there a way to tell?

We never had a thaw this year, in Buffalo, until now so the snow constantly accumulated until this first melt.

What should I do to try to prevent the water penetrating the house next winter? I know there's not much that can be done until Spring/Summer.

Thanks for any help or suggestions.

Ice dams frequently form when the outside temps are still below freezing but the temp of the attic roofing is thawing. The ice melts and strats to run down to the gutter where the roof runs out into the eave where the freeezing temp is present on the shingles that water refreezes and starts to build up. More water melts and gets trapped behind that new little dam and standing water will work its way between the shingles. The cure, more ventilkation of the attic to allow warmed air to escape and maybe even more insulation. Hope you new insulation did not bloch the space between the rafters where the eave vents in fresh air, that must be open.