A floor that bounces, springs, or moves when you walk on it is measuring deflection in the framing below — not normal settling. The bounce doesn’t go away. A forensic inspection finds the cause. A fixed-price repair eliminates it.
We don’t guess why your floors bounce. We go under the house, probe every joist in the affected span, identify the exact cause of deflection, and deliver a written fixed-price repair scope the same day. You know exactly what’s wrong and exactly what it costs to fix it permanently.
Schedule Your Diagnostic →$350 credited 100% toward your repair when you move forward.
Floor deflection is not a quirk of older homes. It is a measurable structural condition — your joist system failing to hold its shape under load. Every bounce you feel is the framing moving. That movement has a cause, and the cause does not resolve on its own.
Joists that were undersized for their span at original construction — or had their bearing length reduced by notching, boring, or alterations — deflect more than design allows. The floor bounces because the joist is flexing beyond its structural limit under normal load.
A joist weakened by fungal decay loses stiffness progressively. The floor may have been solid for years before suddenly developing bounce in a localized zone. Dry rot in a crawl-space joist is the most common cause of concentrated bounciness in PNW homes — especially near plumbing fixtures.
A girder beam or support post that has settled, shifted, or rotted at the base removes mid-span support from the joists above it. Every joist in that bay loses its intermediate bearing point and begins to deflect. The bounce is distributed across a wider zone of the floor.
Moisture-damaged plywood subfloor delaminates — the layers separate and the panel loses structural rigidity. This creates a soft, compliant surface that moves under foot. The joists below may be intact, but the subfloor itself has become the failure point. Replacement is the only fix.
Not all bouncy floors are the same failure. The pattern — where it bounces, how much, and what else is happening nearby — points toward the specific cause. These are the combinations that warrant a forensic inspection.
Load cycles don’t give a compromised joist time to recover. Every step, every furniture load, every seasonal movement adds to cumulative deflection. A floor that bounces slightly today will bounce more in six months if the underlying cause — moisture, decay, missing support — is still active. The repair scope that costs X today grows when adjacent members become involved. Timing is the only variable still in your control.
There is no universal fix for floor deflection. The repair depends on what caused it. That’s why the forensic diagnostic comes first — the repair scope is written after the cause is confirmed, not before.
A full-length sister joist is fastened alongside the deflecting or damaged member, transferring the structural load to new lumber. Access is made from the crawl space — the finished floor above is typically undisturbed. The most common repair for deflection caused by overspan or minor moisture damage.
When bounce is caused by a missing or failed support post or beam, a new mid-span bearing point is installed. This may involve a new steel post on a reinforced footing, an adjustable jack post, or a sistered girder beam — depending on what the forensic inspection reveals.
When a joist is fully compromised by dry rot — hollow or fractured — it must be removed and replaced rather than sistered. The moisture source is identified and corrected simultaneously. New lumber is installed to current span rating standards.
When delaminated or rot-damaged subfloor is the cause of the bounce — rather than the joists below — the compromised panel is removed after joist repair and replaced with new structural sheathing. Floor finish above is reinstated to match existing.
Four steps. Fixed price. One guarantee.
One form or one call. $350 confirmed at booking — no hidden fees, no bait-and-switch scope.
We enter the crawl space, probe every joist in the affected span, and identify the exact cause of deflection with photos.
Written lump-sum repair contract delivered the same day. Your $350 diagnostic fee credits in full toward this price.
APCON LLC performs structural framing directly under WA GC License #APCONL*825QO. 5-year written guarantee on all structural repairs.
The same bouncy-floor symptom can have very different causes. Each row below shows a sub-symptom, the most likely underlying cause, and the repair scope that usually follows. The $350 diagnostic confirms exactly which row applies to your house.
| Sub-Symptom | Likely Cause | Typical Repair Scope |
|---|---|---|
| Bounce concentrated in one room | Localized joist rot or damage; possible subfloor delamination | Joist sistering or replacement; subfloor patching |
| Bounce across whole floor; older home | Undersized or over-spanned joists (common pre-1970 construction) | Mid-span beam addition or joist sistering |
| Bounce + musty smell in crawl | Moisture damage to joists and subfloor from crawl space conditions | Floor joist repair + crawl space encapsulation |
| Bounce near wall; visible sag from crawl | Rim joist or sill plate rot at perimeter; joist bearing failure | Sill plate replacement; rim joist repair; joist shoring |
| New bounce after water event | Subfloor delamination or joist compromise from water exposure | Water damage restoration; subfloor and joist scope |
Not every symptom requires immediate action. Some are structural emergencies that get worse fast and more expensive the longer you wait. Others are stable conditions that can be scheduled at your convenience. Here's how to tell them apart.
Pricing for bouncy floor repair depends on scope: a single sistered joist starts at $750, while a full crawl-space rebuild can reach $18,000 or more. Our Floor Joist Repair Cost Guide breaks down the scope tiers and price ranges for each.
See Floor Joist Repair Cost Guide →A bouncy floor is a structural problem that only gets more expensive to fix over time. The $350 diagnostic tells you exactly what’s wrong and exactly what it costs to fix it permanently — the same day we inspect.
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