NEWBURY — They expect big storms to do big damage on Plum Island, where beach erosion has long threatened oceanfront homes. They just weren’t expecting this storm to be that bad; ultimately, it was the most damaging to hit the island in recent memory.

As high tide arrived Friday morning, an $800,000 house was ripped from its foundation by the crashing surf and toppled onto the beach. Two others were so damaged that they were expected to be a total loss. And another two could end up condemned. All told, 12 homes are in jeopardy on this small barrier island, according to Newbury building inspector Sam Joslin.