ITTOG
Well-known member
I'd think adding a rubber membrane like flex seal at the bottom of the boards would make it rot faster, by trapping water at the bottom. Wood needs to breathe, but also needs to be treated for weather resistance. Be that by oil soaking, such as creosote, chemicals, or used oil with a penetrant. Either way it should be allowed to breathe, while doing whatever you can to prevent water from being trapped in areas where you are capable. JMHO
Yeah that makes sense. Just like the sealer I bought indicated to not apply until the wood is dry. You don't want to trap anything inside the wood. That is probably worse than moisture attacking the outside. I will have to investigate it a bit more.