Translate an engineered repair scope into quantities
Foundation repair costs depend on the cause and location of movement, not simply the total perimeter of a house. A structural professional may specify underpinning at selected locations, while another area needs crack treatment or drainage work. This calculator separates those scopes. Its pier count is based only on a support run and spacing already selected by a qualified professional, and it includes a support at each end of a positive run.
Spacing is not a design recommendation. Soil bearing conditions, foundation loading, existing damage, adjacent structures and proprietary support systems can all affect the required locations. Never select a smaller spacing solely to produce a larger or smaller budget. Use the engineer's drawings or contractor's designed layout as the starting point.
Pier location and repair-cost formulas
Pier budget = illustrative pier count × installed price per pier
Crack-treatment budget = separate crack length × quoted price per foot
Excavation allowance = access surface area × entered access rate
Project total = repair subtotal × (1 + contingency % ÷ 100)
The crack length should represent treatment that is not already covered by an underpinning bid. A visible crack may not require underpinning, while a foundation requiring support may also need repairs to finishes or drainage. Avoid double-charging a scope already included in the installed pier price.
Worked example: a 30-foot support run
An engineer has specified a 30-foot support run with no more than six feet between pier locations. Dividing 30 by six gives five intervals, so the simple layout has six positions including both ends. At 18 feet of separate crack treatment and 150 square feet of access work, the calculator reports those quantities independently.
Changing the spacing to five feet increases the illustrative count to seven positions. That difference is a budgeting sensitivity test, not evidence that either spacing is structurally appropriate. Pier placement must come from the approved repair design.
Check what foundation proposals actually include
Understand whether the contractor's pier price covers excavation, installation, load transfer, backfill and surface reinstatement. If those are included in the unit rate, do not also apply an excavation cost to the same work. Soil reports, permits, structural assessment and monitoring may be separately billed. Drainage correction can be essential if moisture movement is contributing to the problem, but no foundation-repair formula can diagnose that cause.
The contingency field can make the budget more resilient to unknown access conditions, yet it cannot predict concealed damage or turn a planning figure into a guaranteed final price. Obtain a written professional scope before treating the quantities as an order.
Foundation repair questions
Does every foundation crack require underpinning?
No. Cracks differ in cause and significance. The calculator keeps crack treatment separate from structural support because the appropriate method must be determined from an inspection and diagnosis.
Why does the pier count include an extra location?
A positive linear run divided into equal maximum-length intervals has one more endpoint than intervals. A 30-foot run with five six-foot intervals has six endpoints. Actual layouts may use different geometry or omit positions as designed.
Can I use this to determine safe pier spacing?
No. Enter spacing only after a qualified structural professional specifies it for the building and ground conditions. The calculator converts that chosen layout into an approximate count and a quote-based budget.