Jed Holmes was off work with stress when he was found dead from carbon monoxide poisoning at his flat, with remnants of a barbecue fire in a room.
He died on the eve of an Ofsted inspection in July at Hampton Hargate Primary School, Peterborough.
The coroner said the evidence showed he was concerned about the inspection.
"We can't exclude the proximity of the Ofsted inspection at the date of his death," said Gordon Ryall, Peterborough coroner.
"It was that impending inspection that triggered off the action he decided to take.
"There was no need for that. He would have coped quite comfortably with that. It was just perhaps one thing too much for him to deal with at the time."
Mr Holmes suffered from heart problems. His GP told the hearing at Peterborough Magistrates' Court that the headteacher was diagnosed with moderate to severe depression in February.
He responded well to drugs and treatment and gradually returned to work after taking time off.
Dr Neil Sanders said: "The reason for his depression at this time was his feeling of stress and pressure at work and his feeling of letting other people down."
Despite returning to work, Mr Holmes was making plans to retire from teaching at Christmas.
