are them boards on the bottom of them kennels a 1 by 6 or 2 by 6
1x6 decking spaced with the back end of a carpenters pencil. Built on a 2x6 frame, 2' on center. Its more than enough to hold me up much less my 40 to 45lb dogs.
Concrete and raised wood floor have their pros and cons but having the dogs out of the dirt is NICE! Especially if you have flea or parasite issues.
Steve