Further development is posted at my Attic Access web site:
Joists 4x8 at 48" On-Center
https://sites.google.com/site/phillipnormanatticaccess/Home/crawlspace-methods-1
4x6 Joists at 32" oc
https://sites.google.com/site/phillipnormanatticaccess/Home/4x6-joists-at-32-oc
2x8 Joists at 16" On-Center
https://sites.google.com/site/phillipnormanatticaccess/Home/2x8-joists-at-16-oc
