New tortoise enclosure

[Bro bott]

So I’m building an indoor tortoise enclosure and I don’t know what to coat it in for waterproofing. I have a Russian tortoise so it will be blasted at 95 degrees in the basking spot and 85 degrees in the cooler spots. A lot of the stuff I’ve looked at don’t do well under that kind of heat and I don’t know what to do. Any suggestions for what kind of wood sealer? It’s only for the walls because the bottom is made of trex which is already water proof. Thanks!