A bouncy floor is flexing more than healthy framing should.

Bouncing Floors: diagnosed and explained.

A bouncing floor is a floor whose framing flexes more than it should underfoot. Every wood framed floor flexes a tiny amount, but a healthy one flexes so little you never notice. A bouncing floor has crossed into perceptible deflection: dishes rattle in the hutch when someone crosses the dining room, a television wobbles with footsteps, or a spot in the hallway gives slightly like the deck of a boat. The floor structure over a crawl space is a system of joists resting on beams, which rest on posts, which rest on pads in the soil, and bounce means some link in that chain is flexing too far. Sometimes the joists were undersized or spanned too long for the load from the day the house was framed, and decades of use have loosened the system further. More often in our region, something has weakened: moisture has softened the wood, rot or termites have eaten cross section out of joists, a support post has settled into soil that got wet, or blocking and connections have worked loose. Bounce is worth taking seriously precisely because it is early. A floor that bounces today and sags visibly next year is following the normal progression of weakening framing, and the repair is far simpler at the bounce stage. In Southern California, Arizona, and Nevada, the crawl space moisture cycle, dry most of the year with hard winter wetting, is the usual accelerant behind both the wood decay and the settling posts.

For the repair side of this, the foundation repair solutions page lists every method Dalinghaus installs, including the ones that fix problems other than bouncing floors.