Pier and Beam Foundation Cost & Layout Calculator
Estimate the cost and material requirements for post-and-beam foundations. Includes an intelligent layout algorithm to optimize pier spacing and beam placement for decks, cabins, and coastal structures.
1. Structure Dimensions
2. Material Specs
3. Unit Costs (Est.)
About
Post-and-beam foundations (pier and beam) elevate a structure above grade, providing stability in unstable soils, flood zones, or sloped terrain. This tool addresses the primary engineering challenge of such foundations: determining the optimal grid spacing to balance structural integrity with material cost. Excessive span leads to beam sag; excessive piers waste money.
The calculator employs a layout algorithm that references standard load tables. It auto-calculates the required number of concrete sonotubes and treated lumber beams based on your structure's area and selected material dimensions. It warns if the chosen beam size (e.g., 2x6) is insufficient for the requested span, helping prevent structural failure. Pricing data is derived from national averages for pressure-treated lumber and pre-cast concrete.
Formulas
The layout assumes a grid where beams support joists. The number of rows (R) and piers per row (Prow) are derived from spans:
Total linear footage of beam material (Lbeam) for a doubled-up beam design:
Reference Data
| Lumber Size (S-P-F #2) | Max Beam Span (Approx) | Max Joist Span (16" OC) |
|---|---|---|
| 2×6 Double Beam | 5ft - 6ft | 9ft 9in |
| 2×8 Double Beam | 6ft - 8ft | 12ft 10in |
| 2×10 Double Beam | 8ft - 10ft | 16ft 5in |
| 2×12 Double Beam | 10ft - 12ft | 19ft 1in |
| 4×4 Post Load | Up to 8ft height | Max 4000 lbs |
| 6×6 Post Load | Up to 12ft height | Max 8000 lbs |