If there are heat producing devices in the room, it sounds implausible for condensation to occur in significant amounts unless the climate is very, very humid. RH sensors are often very inaccurate, but you can get the indoor dew point from the RH and the temperature[1], and if the floor is warmer than the dew point there can be no condensation. If it is below the dew point, there will be condensation - but the outside air cannot be colder than its own dewpoint, so in this case something must be adding water vapor to increase the absolute humidity in the room, or the floor must be cooled by something other than outside air. (Or the temperature [and dew point] of the outside air must be constantly falling while the indoor air is lagging behind. This can only be a transient situation, and the reverse should happen at some point, drying the floor again) 1: http://andrew.rsmas.miami.edu/bmcnoldy/Humidity.html