A floor that slopes, tilts, or is no longer level is measuring structural movement that already happened below. “It’s just an old house” is not a diagnosis — it’s a guess. A forensic inspection identifies the actual cause. A fixed-price repair corrects it.
We enter the crawl space, measure actual floor slope, identify which structural member moved and why, and deliver a written fixed-price repair scope the same day. You know exactly what caused the slope and exactly what permanent correction costs.
Schedule Your Diagnostic →$350 credited 100% toward your repair when you move forward.
IRC code allows a maximum floor slope of 1/8 inch per foot — about a 1% grade. Most people notice floor slope around 1/4 inch per foot. By the time a slope is obvious to a visitor, the underlying structural movement is significant. Here’s how slope severity maps to structural urgency.
1/8" per foot. Allowable per IRC. Barely perceptible. A marble rolls slowly. No structural intervention required if stable.
1/4" per foot. Most homeowners notice this. Furniture feels uneven. The cause needs to be identified and monitored or corrected.
1/2" per foot. Clearly visible to any visitor. Doors may stick. Active structural failure is almost certainly the cause. Repair is indicated.
1" per foot or greater. Objects roll across rooms. Structural failure is advanced. Immediate forensic assessment and intervention required.
Tacoma’s housing stock — predominantly crawl-space construction built between the 1920s and 1990s — has a specific set of failure modes that produce sloping floors. These are the most common causes we find in the forensic inspection.
A wood post on an undersized footing can sink, lean, or rot at the base — dropping the girder beam it carries. Every joist spanning to that beam drops with it. The result is a floor that slopes toward the failed post, often in the center of a room or along one wall of the house.
The mudsill — the first piece of lumber sitting on the concrete foundation — is perpetually wet in Tacoma’s climate. When it rots, the rim joist and the floor joists sitting on it drop inward. Perimeter floor slope — floors that tilt toward an exterior wall — almost always traces back to mudsill failure.
An undersized or deteriorated center beam loses its ability to hold mid-span elevation. As it deflects under sustained load, the floor above it develops a visible valley running parallel to the beam direction. Slope is often gradual at first, then accelerates as the deflection progresses.
When one section of a crawl space foundation settles more than another — due to soil conditions, drainage, or inadequate footings — the framing above it follows. The resulting slope spans multiple rooms and is often accompanied by cracked drywall at window and door corners as the structure racks.
This is the most dangerous phrase in residential construction. “Settlement” is used to normalize conditions that are actually active structural failures. Here’s how to tell the difference.
| Condition | Normal Settling | Active Structural Failure |
|---|---|---|
| When it occurred | Decades ago — no change in years | Recently or still changing |
| Slope progression | Stable — same level as 10 years ago | Getting worse each year |
| Doors and windows | Operate normally | New sticking or gaps appearing |
| Drywall cracks | Old, stable, painted over | New diagonal cracks at corners |
| Under-floor condition | Dry framing, no active decay | Moisture, rot, or post movement visible |
| Correct response | Monitor annually | Forensic inspection now |
A floor that looks like it stopped settling may still have an active moisture source slowly consuming the post at its base. A floor that looks like it’s actively getting worse may be stable at the framing level. The only way to distinguish between normal settling and active structural failure is to go under the house and look. That is exactly what the $350 forensic diagnostic does.
Any of these conditions appearing alongside a sloping floor moves the situation from “monitor it” to “inspect it now.”
Four steps. Fixed price. One guarantee.
One form or one call. $350 confirmed at booking. No back-and-forth scheduling.
We measure slope, access the crawl space, identify the failed structural member, and determine whether the movement is active or stable.
Written lump-sum contract delivered same day. Your $350 diagnostic fee is credited in full toward this price. No surprises.
APCON LLC performs all structural framing directly under WA GC License #APCONL*825QO. 5-year written guarantee on all structural repairs.
Sloping floors result from different underlying failures depending on slope direction and location in the house. The table below maps common slope patterns to likely causes and the repair scope that typically follows.
| Sub-Symptom | Likely Cause | Typical Repair Scope |
|---|---|---|
| Slope toward exterior wall | Sill plate or rim joist rot; exterior foundation settlement | Sill plate replacement; structural shoring and rebuild |
| Slope toward center of house | Center beam or post failure; inadequate mid-span support | Beam replacement, post reinforcement, or added steel |
| Slope isolated to one room | Localized floor joist rot or damage in that area | Floor joist repair or replacement with subfloor |
| Slope across wide area | Foundation issue or major joist system failure | Full diagnostic – may require structural engineer |
| Slope with visible crack in drywall | Active structural movement; foundation or framing progressing | Urgent diagnostic; escalation to structural engineer likely |
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.
Sloping floor repair can range from joist work at $750 to sill plate replacement at $7,500–$12,000, up to $18,000+ for major rebuilds. Our cost guides break down each scope tier.
See All Repair Cost Guides →The $350 forensic diagnostic tells you exactly which structural member failed, whether the movement is still active, and what it costs to fix it permanently — the same day we inspect.
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