Fleece questions?

Hi everyone! I'm a new chinchilla owner of about two months now. My chinchilla and his cage was a gift from my boyfriend, and not knowing any better he got a cage with plastic shelves in it. Up until a few days ago he did not chew on the plastic, but now he's starting to. So I'm planning on covering the shelves with fleece but I have a few questions. If there is anyone with fleece covered shelves, do your chins pee on them? Right now he only pees on the bedding at the bottom but I'm wondering if he will start peeing on the shelves once they are fleece covered?