Principal Doug McLean said many of the teachers had arrived early and had set up another classroom for George Faga, the Room 1 teacher who lost most of his resources during the blaze.
"They weren't asked to come in but they were here in the morning to support a colleague," Mr McLean said.
"We'll be working through the school holidays to make sure there is no disruption to students when they return after the holidays."
He said he had a sleepless night on Sunday and had dreaded seeing the damage in the cold light of day.
"I think something like this affects you more than you think it will."
Mr Faga was another to have a sleepless Sunday night.
"It's been pretty devastating but I've also been inspired reading some of the comments posted on social media," Mr Faga said.
He was told about the fire as he sat down to dinner with his family on Sunday evening.
James Hohua, a former student, posted online that Mr Faga was the first teacher to help him all the way and never let him down. Work colleague Tania Raynes posted that Room 1 had helped so many tamariki (children).
