The exterior ship lap wood has been treated with borate solution. The smooth side has been doused with Chevron Shingle Oil, while the rough side is raw and awaits it's coat of stain.
Our hero of the day, Andy Knott, came out to spray the wood inside and out. Inside we decided to use a clear oil-based exterior deck sealer.
Just a bit of touching up, staining the fascia boards, and we can put this stage behind us.