Concrete Garage Slab Cost
Comprehensive planning, thickness specifications, reinforcement requirements, and cost estimating guide for this project type.
Concrete Slab Cost & Volume Estimator
Precision multi-layer project budgeting: Materials, Sub-Base, Reinforcement, Labor & Equipment
Quick Project Presets
1. Slab Dimensions & Quantity
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2. Concrete Material Type & Pricing
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3. Project Scope, Reinforcement & Labor
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Estimated Total Project Budget
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Recommended Specifications for This Application
- Standard Slab Thickness: 4 inches for pedestrian flatwork; 5 to 6 inches for passenger vehicles and light trucks; 6+ inches for RV parking pads.
- Concrete Mix Strength: Minimum 3,000 PSI compressive strength for mild climates; 4,000 PSI with air-entrainment (5%–7%) for freeze-thaw climates.
- Sub-Base Preparation: 4 to 6 inches of compacted #57 crushed stone base to allow water drainage and mitigate soil movement.
- Reinforcement: #4 (1/2") steel rebar spaced at 12" to 18" grid centers on support chairs, or 6x6 welded wire mesh.
Installed vs. DIY Material Cost Matrix
| Slab Dimensions | Surface Area | Cubic Yards (4" Thick) | 80-lb Bags (w/ 10% Waste) | Avg. Materials Only | Avg. Installed Cost |
|---|---|---|---|---|---|
| 10 × 10 ft | 100 sq. ft. | 1.23 yd³ | 23 bags | $220 – $350 | $600 – $1,200 |
| 10 × 20 ft | 200 sq. ft. | 2.47 yd³ | 45 bags | $420 – $650 | $1,200 – $2,400 |
| 12 × 12 ft | 144 sq. ft. | 1.78 yd³ | 33 bags | $310 – $480 | $850 – $1,700 |
| 16 × 24 ft | 384 sq. ft. | 4.74 yd³ | 87 bags | $750 – $1,100 | $2,300 – $4,600 |
| 20 × 20 ft | 400 sq. ft. | 4.94 yd³ | 91 bags | $800 – $1,200 | $2,400 – $4,800 |
| 24 × 24 ft (2-Car Garage) | 576 sq. ft. | 7.11 yd³ | 130 bags | $1,100 – $1,750 | $3,500 – $6,900 |
| 30 × 40 ft (Shop/Barn) | 1,200 sq. ft. | 14.81 yd³ | 272 bags | $2,300 – $3,600 | $7,200 – $14,400 |
*Note: Cost ranges reflect typical residential North American pricing ($135–$175/yd³ ready-mix delivered; $6.00–$12.00/sq. ft. installed with sub-base and labor). Actual costs vary by locality and access.
Important Construction Considerations
Ensure adequate slope (minimum 1/4 inch per foot) away from adjoining building walls for proper drainage. Cut control joints to a depth of 1/4 the slab thickness within 12 to 24 hours of pouring to prevent uncontrolled cracking.