I am looking for a bit of advice on how to fix a flooring problem. I want to install some new flooring (good vinyl or laminate) in my kitchen. The cupboards/counters form a U-shape around the problem area, which is about 5' by 10'. 8" Joists are running parallel to the 10' section.
Although I haven't done any extensive measurements, it appears that two of the joists have a slight arc and are slightly higher than the surrounding joists. It is possible that the surrounding joists are too low. In either case, I have a wide hump across the floor. This may be ok for vinyl, but it isn't suitable for laminate/ceramic and certainly isn't very aesthetically pleasing.
To fix the problem, I am considering removing the old vinyl (house is about 6 years old, but the vinyl is in horrible shape), cutting away the 5/8" plywood subfloor in the problem area, and manually planing down the offending joists. Because it is such a small space, I cannot remove the full sheet of plywood without first removing the cabinets/sink/etc....which I definitely do not want to do at this point.
I was thinking of using a reciprocating saw to cut the subfloor from below (exposed joists in the basement). This would allow removing a section of the subfloor without ripping up an entire sheet of plywood. Once the joists were "corrected", I would drop in a piece of plywood (cut to fit). I plan on tacking up some 2x6 to the joists (flush with the top) to provide a solid surface to screw the new subfloor down.
Finally, some levelling compound of some sort might be in order.
My 2nd problem....the floor doesn't seem to be particularly solid....jumping (or simply 'bouncing' without leaving the floor) causes items in the room to shake....particularly at the top of a tall bookcase in the room. I am concerned that this might prevent me from installing laminate/hardwood. I am considering adding an extra 3/8" surface to the entire area (approx. 400 sq. ft.), but don't know if this will buy me anything in terms of a more solid floor. Any opinions? As I said, joists are 8", and the span is probably 10'. I could do some cross-bracing of the joists from below, but again, I don't know if that will result in a more stable floor.
Thanks in advance, Dave