Interactive Concrete Slab, Monolithic Footing & Rebar Calculator
Calculate exact cubic yardage, ready-mix truckloads, rebar grid sticks, gravel subbase, and turnkey vs. DIY costs for monolithic turn-down slabs and footings from 16x24 to 50x70.
Slab Parameters
Thickened perimeter edge for load-bearing walls
Monolithic Slab Cross-Section Engineering Detail
Material Takeoff & Estimated Budget
National Averages23 cu yds delivered (@ $165/yd)
126 sticks (20-ft) + 134 chairs + tie wire
22 tons #57 crushed limestone (@ $38/ton)
1,380 sq ft 10-mil poly with sealed laps
140 LF 2x10/2x12 form boards, bracing & release agent
How to Use This Tool & Frequently Asked Questions
Tips for customizing dimensions, exporting vector .SVG files, and estimating build costs
How to Use This Tool & Frequently Asked Questions
Tips for customizing dimensions, exporting vector .SVG files, and estimating build costs
How thick should a concrete slab be for a barndominium or garage?
Residential living areas require a minimum 4-inch slab (3,000 to 3,500 PSI) with #4 rebar or welded wire mesh. For attached shops, RV bays, or garage bays supporting vehicle lifts or heavy equipment, 5 to 6 inches of 4,000 PSI concrete is strongly recommended.
What is a monolithic turn-down slab?
A monolithic slab pours the slab floor and perimeter footings simultaneously as a single continuous pour. The edges are thickened (typically 12 to 24 inches wide and 12 to 36 inches deep) to bear exterior load-bearing walls and meet local frost line depth requirements.
How many cubic yards of concrete are in a ready-mix truck?
Standard transit ready-mix concrete trucks carry 9 to 10 cubic yards per delivery. For large barndominium slabs (such as a 40x60 requiring ~42 cu yds), deliveries are staged in 4 to 5 truck rotations.
Why add a 10% waste and over-excavation buffer?
Subgrade settling, uneven dirt grading, trench sloughing, and form deflection consistently require 8% to 10% more concrete than raw geometry calculations. Running out of concrete mid-pour creates catastrophic cold joints.