Window will come out before sheeting. Was gonna use treated on the bottom but I have not had a bit of luck with the new California acceptable treated wood. It falls apart faster than plain Doug fir. I miss the days of chromated copper arsenate. I think they use hemp fir now and when they inject it it compromises the wood itself. Every single one I used on my fence is tearing itself apart and splintering to pieces. I don't get it.
I am ok with the DF on the concrete, heck we get about two days of rain a year.