I've had really good luck with industrial floor tile (the cheap square tile kind you can get a box of at hardware stores) for night boxes.
When applied directly to the plywood with the glue that it is intended to be applied to floors it makes the ply more sturdy and impervious to digging and any wetness, and it's easy to clean. You can hose it down, scrape poop off with an industrial floor scraper if any gets stuck, and it holds up to industrial tortoise digging as well It's easy and quick and inexpensive and it's keeping my ply from getting damaged. It takes me a long time for me to build things (properly...I'm really slow and I'd really rather be doing every/anything else) so I really really hate having to do them again or repair damage. It's a small investment in time and expense to avoid repair and it makes cleaning everything out easier for me.
I stuck it down in a pigeon aviary as well (talk about poop...) and it's held up to weekly floor scraping and hosing down.
When applied directly to the plywood with the glue that it is intended to be applied to floors it makes the ply more sturdy and impervious to digging and any wetness, and it's easy to clean. You can hose it down, scrape poop off with an industrial floor scraper if any gets stuck, and it holds up to industrial tortoise digging as well It's easy and quick and inexpensive and it's keeping my ply from getting damaged. It takes me a long time for me to build things (properly...I'm really slow and I'd really rather be doing every/anything else) so I really really hate having to do them again or repair damage. It's a small investment in time and expense to avoid repair and it makes cleaning everything out easier for me.
I stuck it down in a pigeon aviary as well (talk about poop...) and it's held up to weekly floor scraping and hosing down.