· Michael Blair
A floor that bounces or slopes sends most homeowners straight to foundation worry. In Middle Tennessee the cause is usually in the crawl space, where posts settle, girders sag and moisture weakens joists.
What fails down there
Support posts settling into soil because they sit on inadequate footings, or on no footing at all. Girders sagging between posts spaced too far apart. Joists softened by years of high humidity.
Sistered or notched joists from previous plumbing and HVAC work are another common weak point, particularly where a large notch was cut in the wrong part of the beam.
Reading the symptom
Bounce points at joist span or joist condition. Slope points at a support that has moved. Both together often mean a girder line has dropped.
A level and a tape across several points, recorded with dates, tells you whether it is stable or progressing.
- Bounce: joist span or joist condition
- Slope toward the middle: girder or post settlement
- Slope toward an outside wall: foundation or footing
- Localised soft spot: rot, often near a bath or kitchen
- Notched or drilled joists near plumbing runs
Typical repairs
Adjustable steel posts on proper concrete footings, replacing settled timber posts. Sistering joists alongside damaged ones. Adding an intermediate girder line to reduce span.
Lifting is done slowly, over days or weeks, so finishes above have time to adjust. Fast lifting cracks drywall and can damage plumbing.
Fix the moisture as well
Repairing the structure without addressing crawl space humidity means repeating the work. The wood that failed did so because of the environment it was in.
That is why crawl space repair and encapsulation are usually quoted together here, and why quotes that omit the moisture side are incomplete.