Oh, now I see, no mine have no floor but do have a roof which keeps the structure square when set up. Must admit we usually only put half the roof up so you can get to the door but the top is flat so no getting stuck between anything.
When the puppies were in the lounge room or when I use it for bitches in season I have a pce of lino that I put down on the floor to protect the carpet and then put bedding in, a water bucket secured to the side etc
I also find it good if the dogs are getting a bit noisy, doing the, I can smell a girl in season yodel, I can bring them in and put them in the c-crate with a bone and then just wipe down the lino afterwards to get rid of that fresh bone in the house smell. It works as a good distraction for the males.