910 Crawl Space Pros

Sagging Floor Repair

What the work involves in Wilmington and the Cape Fear region, what it costs, and the situations where it is the wrong thing to buy.

Last updated: 2 August 2026

  • ASTM E1745 reinforced liner
  • IRC R408.3 closed crawl space
  • Class I vapor retarder (<0.1 perm)
  • ICC-ES certified flood vents
  • Written scope before work starts

910 Crawl Space Pros provides sagging floor repair across Wilmington and the Cape Fear region. Sagging floor repair addresses floors that bounce, slope or feel soft underfoot by correcting what is happening below them — a failed girder, a settled pier, decayed joists, or inadequate support that was never right to begin with.

What we do on the first visit

Measure the actual deflection with a level across the affected area, then get underneath and find which member is not doing its job. The symptom upstairs rarely sits directly above the cause.

Four causes, and they need different fixes

Bounce without slope usually means joists that are undersized or over-spanned for the load — common in older homes and in rooms that were converted. The fix is additional support or sistering, not lifting.

Slope toward one point usually means a settled pier or a failed footing under it. Slope along a line usually means a girder that has sagged or decayed. Soft, localised give usually means decay in the subfloor or the joist directly beneath.

  • Bounce, no slope → span or joist capacity
  • Slope to a point → settled pier or footing
  • Slope along a line → girder failure
  • Localised softness → decay in subfloor or a single joist

Lifting is slow, and rushing it cracks the house

A floor that has settled over twenty years cannot be lifted back in an afternoon. The structure above has adapted — plaster, drywall, tile and trim have all moved with it — and lifting fast simply transfers the movement into cracked finishes.

Correct practice is incremental: a small adjustment, then time for the structure to relieve, then another. Depending on the amount of settlement that can mean weeks. Anyone offering to level your floor in one visit is telling you what will happen to your walls.

Sometimes the right answer is support, not lifting

Where the settlement is old, stable and not progressing, adding permanent support to stop further movement is often the better purchase than attempting to return the floor to level. It costs less, risks nothing upstairs, and addresses the actual problem — which is movement, not the absolute position.

What's included

  • Level survey establishing actual deflection, not an impression
  • Identification of the specific failed member
  • Adjustable steel jacks on poured footings sized to the load
  • Sistered or replaced joists and girders where decayed
  • Incremental lifting over an appropriate period where lifting is agreed
  • Correction of the moisture source where decay is involved
  • Written explanation of cause, not just the remedy
  • Before and after level readings

DIY, cheap quote, or done properly

Most of the price difference between quotes is not labour — it is which of these steps the quote silently leaves out.

DIY Cheapest quote Done properly
Liner 6 mil builder sheet, laid loose 6–8 mil, taped seams, not fastened to walls Reinforced 12–20 mil to ASTM E1745, sealed to piers and walls
Groundwater Not addressed Sealed over — water ends up under the plastic Drainage and sump first, liner second
Humidity control None, or a household dehumidifier on an extension cord Undersized unit, condensate draining to the soil Unit sized to cubic footage, pumped to a proper discharge
Vents Left open, or foam blocks pushed in Covered, not sealed Sealed and detailed so the space is genuinely closed
Wood already affected Bleach from a spray bottle Surface treated, moisture source left in place Growth removed, framing treated, dried, then sealed
What it costs $300 – $900 in materials $1,500 – $3,000 $4,200 – $14,000
How long it holds A season or two Often fails within a few years Liner life measured in decades when water is handled first

How sagging floors work runs

  1. 01

    Assess and measure

    Humidity, moisture content in the framing, standing water, clearance and access — photographed throughout.

  2. 02

    Written scope

    Line by line, in the order the work has to happen, with a price against each component.

  3. 03

    The work

    Water handled first where present, then the fix itself, then verification.

  4. 04

    Verify and hand over

    Post-work readings recorded and left with you, along with the photographs.

Get sagging floor repair priced for your home

Free on-site assessment across Wilmington and New Hanover, Brunswick and Pender counties.

Sagging Floor Repair questions

How much does sagging floor repair cost?
A single support point on a new footing may be $800–$1,500. A failed girder line with multiple footings and sistered joists runs $4,000–$12,000. The level survey and probe are what produce a real number.
Can a sagging floor be made perfectly level again?
Rarely, and attempting it is often the wrong goal. A floor that settled over decades has finishes that moved with it. Incremental lifting can recover much of the deflection; chasing the last of it tends to crack plaster and tile.
Is a bouncy floor dangerous?
Usually not immediately — it is more often a stiffness problem than a strength one. Localised softness underfoot is the one to take seriously, because that suggests decay rather than deflection.
Why did my floor start sagging?
On the Cape Fear coast, most often sustained crawl space moisture that allowed decay in a girder or joist ends. The second most common cause is a pier footing that has settled in saturated soil.
Call (910) 886-2018