Typical signs
- Squeak, vibration, local dip, visible slope or separation at walls.
Where it is often found
- Wood floors, basements, bathrooms, around openings and below heavy loads.
What it can mean
- Subfloor fastening, notched joist, moisture, excessive span or moving support.
What to check next
- Measure slope and deflection on several dates.
- Inspect below if accessible and note changes/loads.
Reasonable immediate actions
- Reduce concentrated loads if the area seems unstable.
When to stop and call a professional
- Marked sag, damaged joist, shifted post/support or progression.
Prevention
- Avoid unverified notches/holes, keep wood dry and distribute loads.