The formula
For each line item we multiply a quantity by a national unit cost, then apply a quality-grade factor. A regional labor multiplier is applied to the labor portion only; materials are priced nationally. We show the itemized result as a ±35% range.
National unit costs
Regional labor multipliers
Each state's labor multiplier is its mean carpenter wage relative to the national mean, from the U.S. Bureau of Labor Statistics Occupational Employment & Wage Statistics (Carpenters, SOC 47-2031) — used as a construction-labor proxy because drainage crews have no reliably reported 50-state occupation code. Multipliers are bounded to a sane range and applied to the labor share of each line item, so materials stay nationally priced while labor tracks local wages.
Data vintage and limitations
Compiled June 2026 from public cost aggregators and government wage data. These are derived estimates, not live contractor quotes. Local prices vary with project complexity, access, and material availability; always confirm with a licensed contractor before budgeting.
Sources
- https://homeguide.com/costs/french-drain-cost
- https://taxfoundation.org/data/all/state/sales-tax-rates-midyear-2025/
- https://www.angi.com/articles/how-much-does-french-drain-cost.htm
- https://www.bls.gov/ooh/construction-and-extraction/carpenters.htm
- https://www.bobvila.com/articles/french-drain-cost/
- https://www.fixr.com/costs/french-drain-installation
- https://www.homeadvisor.com/cost/landscape/install-french-drain/