Teachers at St Aloysius school in Islington, north London, have voted overwhelmingly to strike.
They are set to strike on Tuesday of next week—the day of the emergency budget.
The workers, in the NUT union, voted by 29 to one to strike in protest at dangerous working conditions.
Private contractor Balfour Beatty is currently rebuilding the school as part of the government’s “Building Schools for the Future” programme.
An independent inspector found a number of safety problems with the new buildings.
Teachers are demanding that their old building is not demolished until they are happy that the new one is safe.