[Aussie Mike]

The yellow tongue flooring is pretty waterproof. It's got a waxy plastic coating on it. Just make sure you put the cut end at the top and you won't need to worry about absorbing water when you wash the floor. I've left off cuts on the trailer for ages waiting to go to the tip and they stand up to the weather amazingly. A bit of water from washing the floor shouldn't cause them an issue.

Cheers