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Walnut CreekFoundation & Retrofit

S-07Leveling & underpinning

House Leveling and Underpinning in Walnut Creek

A sloping floor over a crawlspace is usually fixed by re-supporting the girders with new posts, shims and pier footings. A settling perimeter footing or slab is fixed by underpinning with push, helical or drilled piers. Re-supports often cost a few thousand dollars; underpinning runs $10,000–$30,000+ (HomeGuide).

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Crawlspace with new wooden posts on fresh concrete pier footings supporting a heavy wood girder
New posts and pier footings under a girder line.

01Methods

Two different jobs: re-support vs underpinning

Leveling a raised floor and underpinning a footingLeft: a sagging girder in a crawlspace re-supported with new posts, steel post caps, shims and new concrete pier footings. Right: an existing perimeter footing underpinned with steel push piers and helical piers driven down to firmer soil. DETAIL C1 · RAISED FLOOR RE-SUPPORT GIRDER SAGGING LINE BEFORE 1NEW POST + SHIMS 2NEW PIER FOOTING DETAIL C2 · PERIMETER UNDERPINNING HOUSE WALL PUSH PIER HELICAL PIER EXISTING FOOTING SCHEMATIC ONLY · METHOD, PIER TYPE AND COUNT COME FROM THE ENGINEER OR CONTRACTOR
Fig. 1 · Left: re-supporting a sagging girder. Right: underpinning a perimeter footing with push and helical piers.

Raised-floor leveling

In a crawlspace, the floor rests on girders, posts and small pier footings. Rotted posts, undersized footings or a sagging girder show up as bouncy or sloping floors. The fix: jack the girder in stages, set new posts on new footings, shim, and add connectors. Rotted mudsill sections may be replaced at the same time.

Underpinning

When the perimeter footing or slab itself has dropped, piers are installed under it down to firmer soil. Push piers are driven using the house's weight, helical piers are screwed in and work for lighter loads, and drilled concrete piers are common on hillsides and in expansive clay.

02Slab vs raised

Slab and raised foundations level differently

Raised foundationSlab-on-grade
AccessCrawlspace under the floorOnly from the edges or through the slab
Typical fixRe-support girders, posts, footings; shimPiers under the footing; slab lifting or mudjacking
Cost levelUsually lowerUsually higher
Also checkRotted sills, unbolted sill plate (retrofit)Plumbing leaks under the slab

03What to expect

What "level" realistically means

Older houses were built with some variation, and floors that have sagged for decades have finishes that settled with them. Lifting too far or too fast can crack plaster, tile and drywall. A careful job stabilizes the structure first and recovers as much level as the house tolerates. Budget for door adjustments, patching and paint afterward.

  1. Ask what tolerance the contractor or engineer is aiming for
  2. Ask how many stages the lift will take
  3. Confirm who handles cosmetic repairs, or that they are excluded
  4. Get the permit and final inspection in the scope

04Permits

Permits and inspections

Underpinning and structural re-supports need a building permit. Walnut Creek issues permits through its own online permit system; Danville has its own Permit Center; Lafayette and unincorporated Alamo, Blackhawk and Diablo go through Contra Costa County.

05Questions

Leveling and underpinning questions

Can you live in the house during leveling or underpinning?
In most cases, yes. Raised-floor leveling happens in the crawlspace and underpinning from outside. Expect noise, some doors and cabinets that need adjusting afterward, and possibly a short water or gas shut-off for larger lifts.
How long does house leveling take?
Re-supporting a girder line with new posts and footings can take a few days. Underpinning with piers commonly takes one to a few weeks, plus engineering and permit time before work starts.
Will my floors be perfectly level afterward?
Rarely. Older houses were not perfectly level when built, and forcing a full lift can crack finishes. The goal is usually to stabilize and bring floors back within a reasonable tolerance the engineer or contractor sets.

Sources · read October 4, 2026

  1. HomeGuide: foundation repair cost
  2. City of Walnut Creek: online permits
  3. Town of Danville: Permit Center
  4. Contra Costa County: building or grading permits

Floors rolling toward one corner?

A pro can get under the house and tell you whether it is posts and girders or the footing itself.

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