Schools in England seek alternative spaces amid fears concrete crisis could affect 1,000

Work at a school in Sheffield that is among those affected by the Raac problem. Photograph: Danny Lawson/PA

Teachers are scrambling to find temporary accommodation in libraries, marquees and Portakabins after at least 156 schools in England were identified as having potentially dangerous aerated concrete, and engineers prepared for a weekend checking more schools at risk of sudden collapse.

With an estimated 24 schools already facing temporary closure and the government telling more than 100 to close at least some affected areas, the schools minister, Nick Gibb, said numbers were likely to increase.