Hey all, I’m in Vermont and converting a new shed on piers into a home. I’ve read some great articles here that have helped me figure out the plan for insulating the floor properly, and importantly, not doing skirts to keep air flowing and moisture buildup out from underneath the structure. About 18″ of clearance underneath.

My question is that the shed was assembled about two months ago, and before I insulate and seal everything, I’m wondering about the moisture content of the exposed joists and subfloor.

The insulation plan is that between the floor joists do mineral wool. Then a 1″ polysio board below that on the outside of the joists, seam sealed fastened to the joists. Then ground contact plywood (how thin can I get with that?) fastened below that, with I think flashing tape around the perimeter of the plywood.

The moisture content of the exposed joists and subfloor is between 10-15% depending on where I measure it, most around 12 0r 12%. I have some fans and air movers, and it’s fortunately less humid now, but I am in a valley and do get a lot of fog pretty much each morning. The rest of the interior wood framing and subfloor is around 8-10% which seems fine? But I am generally concerned about moisture/mold esp with today’s lumber, and want to start things right from the beginning, even if that means a little extra work now.

So in total, I think my questions that I’m looking for a little help on are:

1. Is that moisture content high enough that I should try to dry the joists and bottom of the subfloor and sill plates before insulating and sealing?

2. Are there any special tricks to that other than just throwing a fan or air mover down there and letting it rip for a week or two?

3. Any reactions on the overall insulation plan, such as how thin I can do the plywood and if sealing in between the plywood pieces is necessary if the polyiso foam boards above will be sealed, that’s intended to be the air/moisture barrier. There will be a felt or resin layer on top of the subfloor below floating engineered hardwood floors.

Thank you so much! This site has been a great resource already so far in planning.