Shouldn't it be lined with plastic so the wood doesn't produce mold and/or sap?
I was told to never use bare wood to hold substrate without lining it first with pond liner, so that the glue in the plywood doesn't hurt them, and so the wood doesn't get dry rot, have urine soak into it over time etc.
@Mantissa3 what is the best plastic to use? Does it matter? I'm building a pen within the next week and I was just wondering. I was going to get cheap tarps from harbor freight for my liner.
