How to put tea and salt under the stone when building a house, Mi Dou?

This is an ancient saying that houses are built to drive away evil spirits and insects for good luck, but this is just a saying in the past, which is not scientific at all. Now you don't have to put anything in building a house, paste new tiles and brush latex paint on the walls. The new house looks bright and clean. The new house is luxurious and can't be compared with the old one.