We have an outbuilding that used to be a slaughterhouse which we typically use as a party venue during the summer in case of bad weather or for late nights. It has a poured floor with blood channels, making it quite difficult to furnish because of these. Additionally, we have demolished a partition wall to an adjacent storage area where there is a poor simple plank floor with macadam underneath, instead of concrete; between the two floors lies a sill from the demolished partition wall. We are now considering laying flooring over both these areas with 50 mm pine planks that we have received. The question is how many supports I need to arrange. The outbuilding is 360x485 cm.