I have built tons or wood enclosures in the past , and they are great for retaining heat and humidity as long as you can find some way to properly seal the wood your fine . before I switched to building my cages from 1/2" pvc I was useing 3/4' birch plywood lined with formica which worked well but over all I wont go back from my plastic as I can practically let it rain in my pvc cages and it holds heat just as well as wood