I can understand wanting to seal a floor. You never know when there will be a spilled waterer, etc, or the birds decide to scratch an area bare of litter and then poop on it. Mine do sometimes, I assume they are not totally unique ;P
Me, I primed and painted my plywood tractor floor; the floor in their winter quarters is vinyl flooring over plywood over insulation board over concrete (I did not build it that way, it used to be a dog boarding kennel).
I nailed/screwed thin trim all around the edges of the vinyl flooring, to prevent gaps that could catch litter and get nasty in time (which does happen with rubber stall mats in horse stalls, so I was not going to take chances with a chicken stall <g>). I caulked *underneath* the trim (between trim and flooring, and trim and wall) to try to prevent mites from being able to hide under there. I wiped away any caulk that blebbed out, so there is none where chickens could possibly get to it. I am not sure whether it actually succeeds in excluding mites, nor whether it was a good or bad idea; I will tell you I had to air the building out for several days before I stopped smelling caulk and could put the chickens in there :|
Pat