"As soon as you saw it, it was clear that it was completely unsaveable," said Tony Bavington, head of Felix Middle School in Newmarket, which burnt down in August last year, despite the efforts of 70 firefighters.
The blaze, which caused Pounds 6.5 million of damage, was started deliberately by a 14-year-old former pupil, Daniel Mitson, who climbed through a window and lit some paper. The fire is likely to have spread to a cupboard containing paper and then made its way into the ceiling.
"It was almost indescribable - like being slammed into a brick wall," Mr Bavington said.
Tim Young, head of the school's English department, said: "It's hard to explain the nothingness of nothing. You want a stapler? You need to go out and buy one. The same with pens, resources, exercise books, software, computers. Everything that was once automatic becomes like wading through treacle."