Funding that the school had thought was frozen to go towards the rebuild would be available for the upgrade.
Plans for a rebuild and a date for delivery are expected to be announced next month.
"I am extremely confident that everything has been addressed. We know now it's a priority," Mr Luders said.
"I think the wheels are going to be rolling quite quickly. They're going to get things cracking as fast as they possibly can."
And he was grateful to have certainty.
"That's the thing we've wanted the whole way along. It gives us a lot more heart to know exactly where we stand. Moving guidelines are hard to get your head around," he added.
He didn't hold a grudge for the delays, saying the ministry was looking after a lot of money, and the school had got lost somewhere in the process.
The end product was that "the kids" would be the winners.