Marckorbin wrote an answer about Mountain Hardwear Space Station Tent 15-Person 4-Season on June 25, 2012
You can purchase a floor for this tent separately for several reasons.
If you damage your floor you are only out the cost of the floor, not the whole tent.
Many people who use this tent don't need to use the floor.
The tent is waterproofed, the fly it comes with keeps the vent hole on top from letting in the weather.