Situation: Existing uninsulated very shallow crawl space with a concrete floor that doesn’t have insulation or vapor barrier under the slab located in climate zone 6 just a few miles south of the “border” for climate zone 7.

My plan is to insulate the space with 4″ on the walls and 2″ on the slab of type 1 EPS and then cover that with about as much blown cellulose as I can fit in the space (about 2′ high). It is empty space – no mechanicals of any sort in there.

Does it make sense to seal it up once it’s insulated? Or because of the climate zone would insulating the wood floor and then venting the space be more appropriate?

Should there be a vapor barrier on top of the slab and under the EPS in either case?

Or is there a better all around option for insulating the space?

thanks!!