Wood responds to changes in temperature or humidity by warping and that can be bad news for your hardwood floor.
How to fix a warped floor joist.
Most wooden floor joists span a room from wall to wall.
How to straighten warped floor joists.
How to straighten a warped floor.
Lets look over straightening joists in and existing home and hte property of installing underfloor insulation as we go.
If one has warped or moved by 25mm leaving the floor sloping across 4 5 1350mm then the floor will be sitting above the two or three intermediate joists by a noticeable amount and thus be very springy as unsupported.
If the floor is solid and does not move then it could be that the others are out too.
Warping manifests as gaps between the boards.
Setting the joists perfectly level at the house is easy and the beam makes them fairly even near the front edge but the problem is in the middle.