Here are changes suggested by Thom Stanton to accommodate tiny houses on foundations in Virginia:

Suggested Changes to the IRC

by Thom Stanton, American Tiny House Association’s Virginia State Chapter Leader

Thom defines a small house as being not more than 500 sq ft. and suggests these changes:

Section R327, Small Houses

  1. Access to the basements, underfloor areas and lofts shall be by means of alternating tread devices, ladders, or any means that complies with Section R311.
  2. The minimum floor areas of Section R304 shall not apply.
  3. The minimum ceiling height requirements of Section R305 shall not apply.
  4. Lofts used as sleeping areas shall not be required to comply with Section R310 provided that the loft opens to a floor containing an emergency escape and rescue opening.
  5. Basements and underfloor areas shall not be required to comply with Section R310 provided that the
  6. basement or underfloor area does not contain sleeping rooms.
  7. The minimum door sizes of Section R311.2 shall not apply.
  8. The hallway width requirements of Section R311.6 shall not apply.
  9. The guard requirements of Section R312 shall not apply to lofts.
  10. The automatic fire sprinkler requirements of Section R313 shall not apply.

Source:
VUSBC-2016_Tiny-House_Draft-01.pdf