Dog destroys house only when we are not home

[dallasfolk]

We have an 8month old Shar Pei that is very well behaved when we are home. He plays well and is completely house trained. The problem is when we leave the house. He turns into maniac and chews everything within reach. The banister, corners of door, base boards. He also somehow manages to jump up and get things off the table and chew them up. Nothing seems to be off limits of what he chews when we are not home. How do I doscourage this behaviour when it only happens when we are not with him.