The Gargoyle in my Yard by Philippa Dowding

From chapters.ca:
What do you do when a 400- year- old gargoyle moves into your backyard? Especially when no one else but you knows he's alive? Twelve- year- old Kathryn Newberry can tell you all about life with a gargoyle. He's naughty. He gets people into trouble. He howls at the moon, breaks statues and tramples flowers to bits, all the while making it look like you did it! He likes to throw apple cores and stick his tongue out at people when they aren't looking. How do you get rid of a gargoyle? If you're like Kathryn and her parents, after getting to know him, you might really want him to stay...