Vastushastra does not permit a basement. Adequate sunlight and air is absent in a basement and thus the atmosphere there is not conductive to human life.
A basement in the northeast is somewhat permissible.
These days there are many small business run in basements. They may prosper for some time but later face difficulties. Basements are good for beer bars, gambling dens, casinos, video-game parlours etc.
If there is a basement in the entire vastu, then only the one in northeast should be used. And heavy items should be stored in northwest and southwest Otherwise remedial measures can be worked out.