Creating this 7x8 floor costs 40 wood, but when I remove the blueprint, I only get 39 wood back.
Tested multiple times on different sized floors, with the same result each time. Laying 1 floor costs 1 wood, but returns 0 when removing! Not just a visual bug either, I just lost about 10 wood testing this.
Seems to happen with all floors, unless the total resources used is a whole number.