The fire in a vocational school center in Waren (Müritz) was traced back to the work on the roof on Friday by a fire investigator.
On Thursday, according to the police, the fire that broke out in the roof and facade area of the modern school building during lessons resulted in damage of around 75,000 euros.
Several hundred students and the teachers had to leave the school, no one was seriously injured.
Goods - Firefighters had been able to contain the fire by evening.
Workers had previously carried out hot-glue work on the roof, which caused the gable facade to catch fire.
Although the prescribed safety precautions were observed by the workers, they did not succeed in extinguishing the fire.
dpa