The city council was just starting on its pound;315 million Building Schools for the Future project when a colony of protected pipistrelle bats decided that the roof of the technology block at Fulhurst Community College was the perfect place to roost.
With bats in the belfry, the council cannot take the wrecking ball to the condemned block.
Two species of the bats have made nests around the school, where the rebuilding project was to have started. Developers called in a "batman" to advise them. The answer? Leave them till they stop roosting next month.
Michael McPherson, principal of Fulhurst, said demolition of the technology blocks had been postponed. "But everything is in place and we're just waiting for the bats to go," he said.
A spokesman for Natural England said the bats were protected by law and, once they had finished roosting, the school would need to take steps so that they were not tempted to return. Knocking down the buildings should suffice.