My daughter recently moved to a 1924 2-story home. Recently she found a leak in the upstairs bath that ran down into the wall all the way to the basement. The wall is plaster and wood lath and has dried out since the leak was fixed by a plumber. Blistered paint is the only visible problem, and green mold inside that one stud bay.

Her insurance won't cover the repairs because they determined it's a pre-existing problem. Would creating a mist of bleach solution and propelling it into the wall cavity from an opening in the basement, then forcing more dry air into the space be a do-able way to kill the mold? I'm thinking shop-vac exhaust for the cfm needed to carry the mist up and then to dry it out. I also have other types of blowers to use if needed.
As a new homeowner she really can't afford to rip out the wall from the basement to the 2nd floor and I don't think the mold is a threat once it's sealed up.

Thoughts?

 

Adding more moisture to the wall is counter productive, even if it contains bleach. As you said, the mold is not a threat if it's sealed up. Mold that doesn't have moisture to survive is dormant. I certainly wouldn't tear a wall out if that's the only way to get to it.