HALIFAX - A Nova Scotia judge has denied bail to a teenager who locked her adoptive family in their rooms and attempted to burn down the house.

The provincial Court of Appeal decision said the "very troubled" girl had decided to kill her family.

It said she spread an accelerant outside the locked doors of their bedrooms before setting a paper towel on fire, and throwing it on the accelerant as they slept in May 2017.

She left an effigy of herself in her bed, "hoping it too would burn and distract the authorities."

She then fled the house with her cat.

Fortunately, the "disturbing" plan did not work, as nobody was injured and the house survived.

In his decision released today, Justice J.A. Farrar says the girl is suffering from complex issues that require continuing treatment and continues to express a deep hatred of her adoptive parents.

The girl, whose identity is protected by a publication ban, was sentenced to 12 months in custody and six months of community service after pleading guilty to attempted arson in October 2017.

She appealed and sought bail, but Farrar says "a reasonable person would conclude (her) detention is necessary in the public interest."