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Foundation Underpinning Cost Calculator
Foundation underpinning addresses settlement, expansive soils, or new structural loads on existing foundations. Three primary methods — push piers, helical piles, or mass concrete underpinning — each have distinct cost ranges. This calculator sizes the budget for each method including engineering, permits, and a 20% contingency for hidden conditions.
Foundation perimeter to support
Total underpinning cost
$28,200
Labor & materials
$15,000
Number of piers
10
Engineering & permits
$8,500
Contingency 20%
$4,700
How the math works
Foundation underpinning addresses settlement, basement extension, or new load on existing foundations. Push piers ($1,200-1,800 per pier on 6 ft centers) work for residential settlement; helical piles ($1,500-2,500 per pile) for new loads or expansive soils; mass concrete underpinning ($300-500/LF) is most disruptive but doesn't require subsoil access.
Engineering for design and permitting is mandatory in most jurisdictions and costs $5K-25K depending on scope.
How to Use
- Enter linear feet of foundation needing support and depth.
- Choose method (mass, push pier, helical).
- Enter engineering and permit budget.
- Read total cost including 20% contingency.
Frequently Asked Questions
When is each method right?
Push piers: residential settlement on stable lower strata. Helical: expansive soils, weak strata, new loads. Mass concrete: deepening basement or where subsoil access prevented.
Cost per pier?
Push pier $1,200-1,800; helical $1,500-2,500. Spaced every 6-8 feet of foundation. Add $400-800 per pier for finish (wall patching).
DIY?
No — underpinning requires structural engineering, permits, and specialized rigging. Failed underpinning can collapse the entire structure.
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