A gas explosion that killed a man was potentially triggered when he switched on a light or his kettle, an inquest has heard.
Paul Wilmott, 63, died in the blast at his home in Haxby, near York, on 19 February 2016.
Mr Wilmott may have become desensitised to the smell of gas before the blast, caused by a fracture in a corroded gas pipe, jurors were told.
They returned a verdict of accidental death earlier.
Steve Critchlow, from the Health and Safety Executive, said the house had been filled with gas leaking from a pipe buried in Mr Wilmott's concrete floor.
He said: "I would imagine that probably an hour, maximum, would be enough to create this sort of incident."
Given the amount of gas present, a small electrical spark from a contact switch would have been sufficient to cause the explosion, he added.
He said it was not uncommon for people to become desensitised to the smell of leaking gas if they were asleep when the leak began.
The house in Springwood was built in the 1970s and had not been built to modern standards that may have protected the pipe from corrosion, jurors were told.
Forensic metallurgist Dr Elizabeth Geary told the inquest in York that formic acid produced by an ants' nest found in a wall nearby may have contributed to the pipe corrosion.
An inquiry found the copper pipe fractured at a point where two concrete floor slabs met and had moved "possibly as a result of bad weather", coroner Rob Turnbull said.