Apart from his body, investigators could find no other damage in the house.
Dr Kieran McLoughlin, the West Galway coroner, said it was the first time in his 25 year career that he had returned a spontaneous combustion verdict, which is believed to be the first in Ireland.
The inquest on Thursday heard how investigators were baffled as to the cause of death, the Irish Independent reported.
Forensic experts found that a fire in the fireplace of the sitting room where the man's badly burned body was found had not been the cause of the blaze.
The court was told that no trace of an accelerant had been found and there had been nothing to suggest foul play. The coroner said he was satisfied nobody had entered or left the house that night.
The fire which killed Mr Faherty was confined to the sitting room. The only damage was to the body, which was totally burned, the ceiling above him and the floor underneath him.