Drenering old house

Hei, im buying a house in Haugesund. Is an old house, so i wonder how much money will cost to make the drenering. 2 of the sides are already with asfalt, but i dont know if already was the drenering. The house is 230m divided in 4 floors. So really how many m2 is around the house i dont know. Can i get so information about the price? Thank you so much.