If you do, the neighbors' wood smoke may enter your house through the chimney or other avenues (cracks around windows, doors, mud sill
and other framing joints, etc.).
Near the bottom of the 4x4s, hunters installed a 2x6 lumber mud sill
around the perimeter, which keeps the framework from settling into the muddy bottom.
The other method is to staple R-19 fiberglass batts to the mud sill
(member onto which the joists are set) and drape them down to the soil, which needs to be thoroughly covered with 6-mil plastic in any case.
The foundation can also absorb the water and transfer dampness to your basement or rot the mud sill
If there is no vent in the vicinity, check the band joists and, if they are not fully insulated, please do so by placing R-19 fiberglass or Roxul insulation tightly against the band joists throughout the crawl space and staple a plastic vapor retarder to the floor sheathing, the sides of the joists and the mud sill
in each space to protect the insulation from moisture migration.
This can be done with R-19 fiberglass with an integral vapor retarder or plastic stapled to the joists, the mud sill