Garage Floor Concrete Thickness Guide
**Garage floors need 4-6 inches of concrete depending on use.** Standard vehicle parking works fine with 4 inches. Workshops with heavy equipment, car lifts, or stored heavy items benefit from 5-6 inches. Think about how you'll actually use your garage—not just today, but years from now.
Garage Floor Concrete Thickness Guide
Garage floors need 4-6 inches of concrete depending on use. Standard vehicle parking works fine with 4 inches. Workshops with heavy equipment, car lifts, or stored heavy items benefit from 5-6 inches. Think about how you'll actually use your garage—not just today, but years from now.
Quick Answer by Use
| Garage Use | Recommended Thickness |
|---|---|
| Vehicle parking only | 4 inches |
| Vehicle + light storage | 4 inches |
| Workshop (moderate use) | 5 inches |
| Heavy equipment storage | 5-6 inches |
| Car lift installation | 6 inches minimum |
| Commercial/heavy use | 6+ inches |
Standard Residential: 4 Inches
For a typical residential garage used primarily for parking cars:
4 inches is adequate because:
- Vehicle weight is distributed across four tires
- Cars remain stationary most of the time (no repeated flexing)
- Point loads are lower than driveways (no turning wheels)
- Floor is fully supported by compacted base
4 inches handles:
- Passenger vehicles
- SUVs and light trucks
- Motorcycles
- Bicycles and lawn equipment
- Normal residential storage
If your garage is purely for parking and typical homeowner storage, 4 inches works well.
When You Need 5-6 Inches
Upgrade thickness for these situations:
Workshop Use: 5 Inches
If you're setting up a workshop with:
- Workbenches with heavy vises
- Floor-standing power tools (table saws, drill presses)
- Metal fabrication equipment
- Engine hoists or stands
The concentrated loads from heavy equipment warrant extra thickness. A 5-inch floor handles workshop use comfortably.
Heavy Equipment Storage: 5-6 Inches
If you'll store or regularly use:
- Riding mowers (400-600 lbs)
- ATVs or UTVs (500-1,500 lbs)
- Boats on trailers
- Heavy tool chests (500+ lbs loaded)
- Compressors, welders, other heavy equipment
Go to 5-6 inches. These items create higher point loads, especially when moved.
Car Lift: 6 Inches Minimum
Vehicle lifts are a special case:
| Lift Type | Floor Requirement |
|---|---|
| 2-post lift | 6" minimum, engineered |
| 4-post lift | 6" minimum |
| Portable lift | 5-6" with good condition |
| Scissor lift | 4-6" depending on capacity |
Critical: Car lift installation typically requires:
- 6 inches of concrete minimum
- 4,000+ PSI concrete strength
- Specific reinforcement (often rebar grid)
- Engineering review for post placement
Many lift manufacturers specify 6" minimum thickness. Some require 8" or thicker reinforced pads at post locations. Check your lift's specifications before pouring.
Reinforcement Requirements
Garage floor reinforcement depends on use:
| Use | Reinforcement |
|---|---|
| Parking only (4") | Wire mesh (6×6) |
| Workshop (5") | Wire mesh or light rebar |
| Heavy equipment (5-6") | Rebar (#4 @ 24") |
| Car lift (6"+) | Rebar per engineering |
Placement
Reinforcement should sit at mid-depth or slightly below:
- 4" slab: Reinforcement at ~2" from bottom
- 6" slab: Reinforcement at ~2.5-3" from bottom
Use rebar chairs or concrete blocks to support reinforcement at proper height. Mesh or rebar lying on the ground provides minimal benefit.
For complete reinforcement guidance, see when to use rebar.
Slope for Drainage
Garage floors should slope slightly toward the door for drainage:
Recommended slope: 1/8" to 1/4" per foot
For a 20-foot deep garage at 1/8" per foot, the back wall is 2.5 inches higher than the door threshold.
Why slope matters:
- Drains water from wet vehicles
- Prevents standing water from snow/rain
- Easier to wash out the floor
- Reduces moisture problems
Connection to Driveway
Where the garage floor meets the driveway:
Option 1: Continuous pour Pour garage and driveway together with a control joint at the transition. Provides seamless connection but requires large single pour.
Option 2: Separate pours with expansion joint Install 1/2" expansion joint material between existing driveway and new garage floor (or vice versa). Allows independent movement, easier scheduling.
Threshold considerations:
- Maintain similar heights to avoid trip hazards
- Consider drainage direction at the connection
- Some codes require specific threshold details
Existing Garage Floor Considerations
If you're evaluating an existing garage floor:
Signs of Inadequate Thickness
- Cracking in tire track areas
- Settlement near lift posts
- Crumbling at high-stress points
- Visible flexing under heavy loads
Can You Add Thickness?
Overlay options:
- Thin overlays (1/4"-1/2") for cosmetics only—no structural benefit
- Thick overlays (2"+) possible but have bonding challenges
- Self-leveling compounds for minor leveling only
Usually better: If structural thickness is inadequate for your needs, removal and replacement is often more reliable than overlay.
Cost Considerations
| Thickness | Concrete/400 sqft | Cost Difference |
|---|---|---|
| 4 inches | 4.9 cubic yards | — |
| 5 inches | 6.2 cubic yards | +$195-260 |
| 6 inches | 7.4 cubic yards | +$375-500 |
Based on $150/yard ready-mix
For a typical 20×20 garage (400 sqft):
- 4" floor: ~$735 in concrete
- 6" floor: ~$1,110 in concrete
- Difference: ~$375
If there's any chance you'll install a lift or use the garage as a serious workshop, the extra $375 for 6 inches is worth it. Retrofitting later costs far more.
For guidance on whether to tackle this yourself, see DIY vs contractor.
Frequently Asked Questions
Is 4 inches enough for a garage floor?
For standard vehicle parking and light storage, yes. 4 inches is adequate when properly installed on a compacted base. However, if you plan to use the garage as a workshop, store heavy equipment, or install a car lift, go with 5-6 inches.
How thick for a car lift?
6 inches minimum, often with specific reinforcement requirements. Check your lift manufacturer's specifications—some require 8 inches or thicker reinforced pads at post locations. Don't install a lift on a 4-inch floor without engineering review.
Do garage floors need rebar?
Wire mesh is sufficient for standard parking use on 4-inch floors. For 5-6 inch floors with heavier use, rebar (#4 at 24" spacing) provides better reinforcement. Car lift installations typically require rebar per engineering specifications.
Key Takeaways
- 4 inches: Adequate for standard parking
- 5 inches: Better for workshops, moderate heavy use
- 6 inches: Required for car lifts, heavy equipment
- Slope: 1/8" to 1/4" per foot toward door
- Reinforcement: Wire mesh minimum; rebar for heavier use
- Plan ahead: Going thicker now is cheaper than replacing later
Next Steps
- Calculate materials: Garage Floor Calculator
- Compare to driveway: Driveway Thickness
- All thickness requirements: Thickness Guide
- Complete planning: Concrete Guide
- Browse all resources: Concrete Guides