I just bought a 25 year old townhouse only to realize after buying it that the second story floors are uneven.
It was just remodeled with new hardwood floors and the previous owner apparently did not address this wavy subfloor issue. The uneveness is significant. The chairs on the hardwood floor rock back and fourth as all four chair legs don't touch the floor at one time.
How concerned should I be about this and if I try to fix it what would be the correct approach?