Normally, all waterproofing of basements is done on the outside when the house is built. Because concrete and block is porous you have to stop the water before it gets into the foundations and the walls. Putting waterproofing on the inside doesn’t really work very well. Which means that waterproofing an existing basement is very difficult and expensive. If you have water in the basement issues often the best way to deal with it is to dig french drains around the house and try to divert the water before it hits the basement walls.
