8x10 Shed Foundation: Complete Concrete Calculator

An 8×10 shed is the perfect size for most homeowners—big enough for lawn equipment and tools, small enough to fit in a typical backyard. But before you build, you need a solid foundation. The wrong foundation leads to sagging floors, stuck doors, and a shed that shifts every spring. The right foundation lasts 30+ years with zero maintenance. Let's calculate exactly what you need and compare your options.

Quick Answer: An 8×10 shed foundation has three main options: concrete slab (1.0 cubic yards, $400-700 DIY), concrete piers on 4 corners ($200-350 for materials), or continuous footings ($300-500). Piers are the most cost-effective for standard storage sheds. Slabs are best if you need a smooth floor. Both options take 1-2 weekends to complete.

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Foundation Options Compared

There are three main foundation types for an 8×10 shed. Each has different costs, difficulty levels, and use cases. Here's the complete breakdown.

Option 1: Concrete Slab (Full Floor)

A concrete slab is a solid 4-6 inch thick pad that covers the entire 8×10 footprint. The shed sits directly on the slab.

Pros:

• Smooth, level floor perfect for workbenches and heavy equipment
• Prevents moisture and pests from entering shed
• Most durable option (30-50 year lifespan)
• No separate flooring needed

Cons:

• Most expensive option ($400-750 DIY)
• Requires significant excavation and site prep
• Need 2-3 helpers for pour day
• Permanent—can't easily relocate shed

Best for: Workshops, heavy equipment storage, areas with high moisture or pest problems, permanent installations.

Option 2: Concrete Piers (4-6 Posts)

Concrete piers are cylindrical columns poured in holes at each corner and optionally along the sides. The shed's floor frame sits on top of the piers.

Pros:

• Most cost-effective option for standard sheds
• Easy to level on sloped ground
• Good drainage (air flows under shed)
• Can work alone (no helpers needed)
• Shed can be relocated if needed

Cons:

• Requires separate shed floor construction
• Pests and moisture can get under shed
• Floor may feel bouncy without proper support
• Not suitable for heavy equipment

Best for: Standard storage sheds, sloped yards, budget-conscious projects, DIYers working alone.

Option 3: Continuous Footings (Perimeter Foundation)

Continuous footings are trenches filled with concrete around the shed's perimeter. The shed walls sit on top of the footings.

Pros:

• Excellent for frost-prone areas (extends below frost line)
• Provides solid perimeter support
• Good for larger sheds or those with heavy walls
• Can add gravel floor inside for drainage

Cons:

• More excavation work than piers
• Requires precise leveling and forming
• Still need separate floor construction
• Mid-range cost ($300-500)

Best for: Cold climates with deep frost lines, larger sheds, areas with strict building codes.

Concrete Slab Foundation: Complete Guide

If you're going with a full concrete slab, here's the step-by-step process and material list.

Materials Needed for 4-Inch Slab

Add tool rentals: Plate compactor ($60-90/day), finishing tools ($40-60 to buy). Total project cost: $400-550 DIY.

Installation Steps

Day 1-2: Site Prep

1. Mark 8×10 area with stakes and string
2. Excavate 8-10 inches deep (4" gravel + 4" concrete + leveling)
3. Compact soil with plate compactor
4. Spread 4 inches of crushed gravel, compact in 2-inch lifts

Day 3: Forms and Rebar

1. Build 2×4 forms around perimeter, stake every 3-4 feet
2. Level forms precisely (use 4-foot level, check diagonals)
3. Lay 6-mil plastic vapor barrier over gravel
4. Install #3 rebar in 18-24 inch grid, use chairs to elevate 2 inches

Day 4: Pour and Finish

1. Schedule concrete delivery for early morning
2. Have 2-3 helpers ready (critical for small pours)
3. Pour concrete, spread with shovels and rakes
4. Screed level with 2×4 across forms
5. Bull float while concrete is wet
6. Wait for bleed water to evaporate (30-60 minutes)
7. Edge perimeter and cut control joints
8. Broom finish for texture
9. Cover with plastic and keep moist for 7 days

For detailed slab instructions, see our guide on pouring concrete slabs.

Concrete Pier Foundation: Complete Guide

Piers are the most popular choice for 8×10 sheds. Here's how to install them correctly.

Pier Layout Options

For an 8×10 shed, you have three pier configurations:

• 4 piers (minimal): One at each corner. Works for light-duty sheds, but floor may feel bouncy.
• 6 piers (standard): Four corners plus two mid-points on long sides. Best balance of cost and support.
• 9 piers (heavy duty): Full 3×3 grid. Use for workshops or heavy equipment storage.

Recommended: 6 piers for most 8×10 sheds. This provides adequate floor support without excessive cost.

Materials for 6-Pier Foundation

Installation Steps

Day 1: Layout and Excavation

1. Mark 8×10 shed footprint with stakes and string
2. Mark pier locations (corners + midpoints on long sides)
3. Dig holes 12 inches diameter, 36 inches deep (or below frost line)
4. Add 4-6 inches of gravel to bottom of each hole

Day 2: Set Tubes and Pour

1. Place sonotubes in holes, extend 4-6 inches above ground
2. Level tubes and brace with stakes
3. Mix concrete (2-3 bags per pier)
4. Pour concrete into tubes, eliminate air pockets with stick
5. Insert post bracket or J-bolt while concrete is wet
6. Check level one final time
7. Let cure 24-48 hours before building on piers

Day 3-4: Build Floor Frame

1. Attach 4×4 posts to pier brackets
2. Build perimeter frame with 2×6 or 2×8 lumber
3. Add floor joists every 16 inches
4. Install 3/4-inch plywood flooring
5. Build shed walls on top of floor

Use our post hole calculator to determine exact concrete amounts for your pier depth and diameter.

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Cost Comparison: All Foundation Types

Here's the complete cost breakdown for each foundation option, including materials and typical tool rentals.

Best value: Concrete piers offer the best balance of cost, durability, and DIY-friendliness for most 8×10 sheds. Save $200-400 compared to professional installation.

Common Mistakes to Avoid

Mistake #1: Skipping Frost Line Depth

Digging only 18-24 inches deep in a cold climate guarantees frost heave. Your shed will shift 1-2 inches every winter, causing doors to stick and walls to crack. Always dig below your local frost line—typically 30-42 inches in northern states. Check with your building department for exact depth requirements.

Mistake #2: No Gravel Drainage Layer

Pouring concrete directly on dirt creates a water trap. Water pools at the base, causing concrete to crack and wood to rot. Always add 4-6 inches of crushed gravel at the bottom of holes or under slabs. This provides drainage and prevents settling.

Mistake #3: Uneven Pier Heights

If piers are off by even 1 inch, your shed floor will be sloped and doors won't close properly. Use a laser level or water level to ensure all piers are exactly the same height. Check and recheck before concrete sets—you can't easily fix this later.

Mistake #4: Inadequate Floor Support

Using only 4 corner piers for an 8×10 shed creates a bouncy, weak floor. The center will sag over time. Always add at least 2 mid-span piers (6 total) for proper support. For heavy equipment or workshop use, go with 9 piers in a full grid.

Mistake #5: Building Without Permits

Many areas require permits for sheds over 100-120 sq ft or those with permanent foundations. An 8×10 shed (80 sq ft) usually doesn't need a permit, but rules vary. Check with your local building department and HOA before starting. Unpermitted structures can cause problems when selling your home.

Sloped Yard Considerations

If your yard has a slope, foundation choice becomes critical. Here's how to handle different slope conditions.

Gentle Slope (Less than 6 inches across 8-10 feet)

Best option: Concrete piers of varying heights

Dig piers to the same depth, but extend them different heights above ground to create a level platform. The uphill piers will be shorter above ground, downhill piers taller. This is easier and cheaper than excavating to create a level pad.

Moderate Slope (6-12 inches across 8-10 feet)

Best option: Stepped piers or partial excavation

Either build tall piers on the downhill side (up to 24 inches above ground is acceptable) or excavate the uphill side to create a more level building pad. Tall piers need proper bracing and may require building code approval.

Steep Slope (More than 12 inches across 8-10 feet)

Best option: Hire a professional or choose a different location

Steep slopes require significant excavation, retaining walls, or very tall piers that need engineering. The cost approaches or exceeds professional installation. Consider relocating the shed to a flatter area or hiring a contractor.

Regional Considerations

Foundation requirements vary by climate. Here's what to watch for in different regions.

Final Takeaway

For an 8×10 shed foundation, concrete piers are the best choice for most DIYers—they cost $200-350 in materials, take 1-2 days to install, and provide 30+ years of solid support. Use 6 piers (four corners plus two mid-points on long sides) for proper floor support. Dig below your frost line (typically 30-42 inches in cold climates) and add 4-6 inches of gravel for drainage.

A full concrete slab ($400-700 DIY) is worth the extra cost if you need a smooth workshop floor or plan to store heavy equipment. It requires 1.0 cubic yards of concrete for a 4-inch thick slab, plus gravel base and rebar. You'll need 2-3 helpers for pour day and proper site preparation.

Use our concrete slab calculator for exact measurements, or our post hole calculator for pier foundations. Always check local building codes and frost line depths before starting. With proper foundation work, your 8×10 shed will remain level and functional for decades with zero maintenance.