Three school-building projects in Bristol have gone £2m over budget.
The school will fully open next year
Redland Green was due to cost £30.5m, but a report before the city council predicts this will now rise to £31.6m, a rise of more than £1.2m.
The council blames the overspend on poor project management and changes to the school's design.
Work at Fairfield school has gone £430,000 over budget, as has work on the Charnwood Centre at Cotham School. which is nine weeks behind schedule.
The overall budget for Fairfield, which has had problems with acoustics and ventilation, was £22.4m.
About £5m had been set aside for the Charnwood Centre.
The Redland Green school is now open off-site with year 7 currently being taught at the former Fairfield School building in Fairlawn Road.
Years 7 and 8, plus the first year 12 intake, will be based at Redland from September 2007. This is not expected to change with the over-spend.