||11-14-2010 01:26 PM
Depends. The notches might not be bad enough to structurally compromise the joists to the point of being detrimental. Adding a wall might add load to something that isn't made to take it (basement slab, joists beneath, etc.).
My advice would be to consider attaching sister joists to the joists to re-structure them. Another viable repair is to use Simpson roll-strapping on the underside of the joists with adequate nailing to restore their tensile strength, if the notches are small. Best advice is to have an engineer take a look at it for you to recommend the best course of action.