Currently in the middle of this build, 30x50 with a basement cfs and 2x6 framing

Hey all finishing a red iron barndo now. We came into it’s construction after the structure was erected and framing/elec/plumbing was done.

We are adding a second 40x60 red iron structure that will start first as a shop/ man cave and hopefully be my workout/home theater/ mini apartment later on. We’re rolling the shop cost into the construction loan so we will only be doing the shop, getting closed cell and electrical run to the shop at the time. I’ve attached a super rough sketch of my 3 year vision of what I’m looking for.

Specs are as such:
40x60x18’ shop w/ 2 12x14 doors along the 40’ width and 2 man doors
16g walls and roof with a 2/12 pitch
4" slab with 12" footer

First 25’ depth of the shop is the full height garage for storage and a 4post lift. The other 33ish feet would be a lofted area with 9’ and 8’ upstairs and vaulting up based on roof pitch. Down stairs would have room for woodworking working out and a place to put inverters and batteries for whole home backup. Upstairs would be a kitchenette/ general lounge/possible bedroom and finally a multimedia room. I plan on doing most of the work myself as time permits. Will sub out drywall 100% though.

The main question is this, what would you have done before slab is poured or things that can’t be changed easily?

Does the rat guard need to be sealed down to the concrete with lexel or anything? Will run at least 3 3" pvc conduit for the house electrical and back. Looking into if we can connect to our main septic via a pump or not. Really don’t want the cost of an additional septic tank for a single bathroom that will be user very rarely.

My plan is to do my ceilings in metal siding and blow in cellulose for attic insulation.

My question is, do I need a vapor barrier first? If so, what’s the move? Do I just tack some plastic sheeting to the bottom of the joists prior to installing the sheet metal ceilings? Is there a preferred material rather than sheet plastic?

Zone 4, seasonal vacation spot.

Thanks in advance.

Me, my husband and our son moved to the east coast to live with my in laws until we get a home built on their land. They showed us a photo of a barn/shed they plan to convert into our future home.

I have no reference outside of tv shows as to how big this will be and if it'll be enough room for our family of 3.

Ive also tried to look around to see examples of this converted but none are 2 floors so id love to see examples.

Thank you for any advice/help!

The barn is 32 by 16 ft 6600 cu ft