Share 'Sealing crawlspaces and insulating them with polyurethane foam'

Joe Lstburek and John Tooley are both sold on sealing crawlspaces.  I saw a short bit of "Holmes Inspections" on HGTV where they sprayed 2 lb polyurethane foam directly onto the dirt floor underneath a raised kitchen addition and sealed the crawlspace essentially turning it into (semi?) conditioned space. I think they sprayed it onto the dirt, I could be mistaken. My question is: Does it make sen…