Crawl space support jacks Cost in Fairfax, Virginia
An adjustable galvanized-steel support post is set on a newly poured concrete footing beneath the girder or joists, then raised in small increments over days or weeks so the floor returns toward level without cracking the finishes above.
In Fairfax, the Coastal Plain clays and locally high water tables here matter less for this particular repair: a floor that sags over a crawl space usually traces to joist span, moisture, or a failed post rather than to soil movement. Local labor rates, your home's age, and site access then set where in the crawl space support jacks range your job lands.
Typical figures from local cost data, not a quote. Estimate your specific job →
When crawl space support jacks are used
Used when floors over a crawl space sag or feel bouncy, when joists or a girder span too far between supports, or when existing posts have rotted, rusted, or settled. This is interior structural support, not perimeter underpinning: it carries the floor framing, where push piers address a foundation that has settled. A home can need one, the other, or both.
Lifespan: A galvanized post on a correctly sized footing is a long-term repair, and adjustable designs can be fine-tuned later if the structure moves again.
Crawl space support jacks costs near Fairfax
Local labor rates and soil differ across the region, so the same job prices differently a short drive away. These are the closest markets we cover.
- Arlington10 mi$1,900 to $7,500 typical
- Alexandria10 mi$1,900 to $7,650 typical
- Manassas15 mi$1,850 to $7,450 typical
Why costs differ in Fairfax
Soil & geology
Fairfax County straddles the fall line: Piedmont clay-rich saprolite over crystalline rock (plus a Triassic-basin sliver) in the west, and the Atlantic Coastal Plain to the east. Its problem soils are the Coastal Plain "marine clays," which swell when wet and shrink when dry; per the county these occur widely east of Interstate 95 and cause poor foundation support, slope instability, and poor drainage.
Permits
Foundation and underpinning work is a structural repair requiring a building permit from Fairfax County Land Development Services. Under the Appendix Q fee schedule (effective July 1, 2025), repairs and alterations to an R-3/R-4/R-5 dwelling are charged at 3.0% of the estimated cost of construction, subject to a $135 minimum, plus a 2% state levy, roughly $300-$600 on a $10,000-$20,000 job.
Local labor
Construction labor here runs 7% below the national average (RSMeans index 0.929), which is applied to every estimate on this page.
Housing stock
The median Fairfax home is about 43 years old, in Fairfax County. Older homes carry more unknowns behind a foundation repair.
Where these numbers come from
Every figure on this page traces to a published source, with the date we retrieved it. The Fairfax soil, permit and labor figures come from Fairfax County Land Development Services, Virginia DMAS and US Census Bureau. The national crawl space support jacks cost range and method guidance come from HBG Civil, CrawlRepair and VFS Works. Ranges are typical costs, not a quote.
- Fairfax County / Northern Virginia Soil and Water Conservation District
- Fairfax County Land Development Services (Appendix Q Fee Schedule)
- Virginia DMAS, RS Means Data (Jan-2025 RSMeans location factors): Fairfax (ZIP 220-221) = 92.9
- US Census Bureau, ACS 2024 5-year, table B25035 (via Census Reporter)
- US Census Bureau, 2023 Gazetteer (INTPTLAT/INTPTLONG)
- HBG Civil
- CrawlRepair
- VFS Works
Frequently asked questions
How much does crawl space support jacks cost in Fairfax?
In Fairfax, crawl space support jacks runs about $460–$1,860 per jack, or roughly $1,850–$7,450 for a typical job. Exact cost depends on the extent of the work. Use the calculator for an estimate specific to your home.
When is crawl space support jacks the right fix?
Used when floors over a crawl space sag or feel bouncy, when joists or a girder span too far between supports, or when existing posts have rotted, rusted, or settled. This is interior structural support, not perimeter underpinning: it carries the floor framing, where push piers address a foundation that has settled. A home can need one, the other, or both.
How long does crawl space support jacks last?
A galvanized post on a correctly sized footing is a long-term repair, and adjustable designs can be fine-tuned later if the structure moves again.
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