Thanks, Rick. I don't care about the drywall, but won't cutting those other boards just further worsen my problem? Then the support will be really messed up. I have much better access on one side of the joist than the other. Can I do the one side as best I can (the width of the staircase,
3-4 ft), and then do another longer piece of wood on the other side? Id say I have about 6 feet of access there.