In just one spot in one of my bedrooms I have a creak when I step on the floor. The creak is in sort of a line for 4 or 5 feet, so I suspect it is caused by a particular joist that lies below that area. Maybe the joist is too low and has a gap between it and the subfloor, or maybe the joist itself has a defect and is missing wood or is warped. Right now the subfloor is exposed because I am redoing the floor. The subfloor where the joist is appears to be perfectly flat.
Is the right way to fix this to try to insert shims between the offending joist and the subfloor? If so, is the right procedure to cut out the ceiling below the joist (which happens to be in a garage) insert the shims, then patch the ceiling?
Note that the location of the creak is where an electrical run is. Not sure if that is a coincidence or related.