slab_length_width_dimensionsHorizontal Planar Dimension
Planar horizontal dimensions of the slab formwork in feet or meters. ACI 360R guidelines recommend maintaining aspect ratios (length-to-width) below 1.5:1 for individual slab panels between contraction joints to prevent longitudinal drying shrinkage cracking.
Default: 10 ft × 10 ft (3.05 m × 3.05 m)
slab_thickness_depthVertical Cross-Sectional Depth
Vertical thickness of the poured concrete slab. Official residential building code (IRC Section R506 / ACI 332) mandates a minimum nominal thickness of 3.5 inches (90 mm) for pedestrian walkways and non-load-bearing patios, 4 inches (100 mm) for storage sheds, 5 to 6 inches (125 to 150 mm) for vehicular driveways, and 8 inches (200 mm) for heavy commercial or RV pads.
Default: 4.0 inches (100 mm)
waste_contingency_factorVolumetric Safety Markup Percentage
Compounded volume percentage added to theoretical solid geometry. Accounts for uncompacted subgrade dips, rutting, excavator grading variations (each 1/4-inch subgrade depression adds ~6.25% to a 4-inch slab), and hydrostatic outward bowing of wooden perimeter forms during screeding. Professional contractors specify 10% for prepared soil and 15% for rocky or unlevel ground.
Default: 10% (Range: 5% to 20%)
gravel_subbase_depthGranular Aggregate Bed Thickness
Depth of crushed stone (#57 limestone or dense graded aggregate / crusher run) installed beneath the slab. Provides uniform compressive bearing capacity, breaks capillary action to prevent moisture wicking into the concrete, and allows frost-heave drainage in freeze-thaw climatic regions.
Default: 4.0 inches (100 mm)
rebar_reinforcement_specificationStructural Steel Reinforcement Schedule
Specification for deformed steel rebar (ASTM A615 Grade 60) or welded wire reinforcement (ASTM A1064). Rebar sizes #3 (3/8" / 10mm) and #4 (1/2" / 12mm) placed on chairs at 12 to 18-inch centers supply tensile resistance against slab differential settlement, bridge subgrade voids, and keep hairline shrinkage cracks tightly interlocked.
Default: #4 Rebar at 18-inch On-Center Grid
concrete_compressive_strength_psi28-Day Curing Strength Rating
Standard compressive strength measured after 28 days of moist curing (ASTM C39). ACI 318 classifies concrete applications: 2,500 PSI for basic footings, 3,000–3,500 PSI for residential patios and sidewalks, 4,000 PSI for exterior garage floors and driveways subject to freeze-thaw and deicing salts, and 4,500–5,000 PSI for heavy industrial slabs.
Default: 3,500 to 4,000 PSI (24 to 28 MPa)
