Arsonists set fire to bins behind a house in Accrington on Saturday night.
Flames spread to the roof of the house on Park Road and its kitchen and utility room.
A spokesman for Lancashire Fire and Rescue Service said: “Hyndburn fire crews were called out on Saturday, November 19 at around 9pm. No one had to be rescued from inside the house and no one was hurt.
“A resident living nearby told us a firework had gone off near the house earlier.
“We are not sure if this is what started the fire but are looking into the cause as are the police.”
He added: “It was soon put out but one wheelie bin and rubbish was destroyed by fire and a two metre section of plastic guttering and one metre of timber roofing were also destroyed. There was light by smoke damage to the kitchen and utility room.”
