Stephen Brownell told police officers he dropped his cigarette after nodding off.
He was accused of wilfully setting fire to the structure in Spruce Way last August, but the Crown accepted his plea of guilty to the less serious alternative charge of culpable and reckless conduct.
Brownell (36) of Clydesdale Road, Mossend, avoided a prison sentence when he appeared at Hamilton Sheriff Court.
Wendy McAdam, prosecuting, said Brownell’s partner was the sister of the woman who lived at the address.
The fiscal said he didn’t get on with the woman and her husband.
Ms McAdam told the court: “The couple were staying elsewhere at the time of the fire.
“It was shortly after 5pm on a Saturday when neighbours saw the accused go into the rear garden. He appeared to be wandering back and forward from there to the side of the house.
“After about 15 minutes he left and five minutes after that the witnesses saw smoke coming from the man cave.
“Firefighters extinguished the blaze. The senior officer said if they hadn’t it would have burned itself out.
“There was no danger to life and no chance of it spreading to other property.”
A TV and a couch were destroyed and the cost of damage was estimated at around £2000.
The prosecutor added: “Brownell was traced and interviewed by police officers. He accepted he had been in the man cave.
“He said he had been having a cigarette, had fallen asleep and must have dropped the cigarette, starting the fire.”
Ian Scott, defending, said Brownell’s life has been “blighted” by drug and, latterly, alcohol addiction, but told the court: “Since this incident he hasn’t touched a drop of drink.
“The social work report in this case is positive in its terms.
“He is the breadwinner for his family and they are expecting another child. He spends a considerable amount of time at work.”
Sheriff Marie Smart said she was prepared to impose a community payback order as an alternative to jail.
Brownell was placed under supervision for 18 months and told he must attend addiction services if required.
The sheriff told him: “I take account of your guilty plea at an early stage.
“Due to your being in full time employment I won’t impose an order for unpaid work.”