Gravel Pad vs. Concrete Slab: Which Foundation for Your Shed?
Your foundation determines how long your structure lasts. The wrong choice can cut its lifespan in half. Here’s how to pick the right one.
Updated for 2025 · Based on thousands of installations since 1988
In This Guide
The Quick Answer
For most sheds and portable garages: go with a gravel pad. It costs 60–75% less, drains better, installs in a day, and is the #1 foundation we recommend. A concrete slab is only necessary for modular garages, heavy workshops, or structures that need to double as a floor.
✅ Gravel pad is right if:
- You’re placing a shed or portable garage
- The structure has a built-in wooden floor
- You want to save money
- You might relocate the structure later
✅ Concrete slab is right if:
- You’re building a modular garage on site
- Vehicles will drive in and out daily
- Your township requires it
- The structure won’t have a built-in floor
Side-by-Side Comparison
| Feature | Gravel Pad | Concrete Slab |
|---|---|---|
| Cost (10×12 pad) | ~$1,200 | ~$5,000+ |
| Installation time | 1 day | 3–5 days + curing |
| Drainage | Excellent — water passes through | Poor — water pools or runs off |
| Best for | Sheds, small garages | Large garages, heavy workshops |
| Relocatable? | Yes — easy to remove | No — permanent |
| Supports vehicles? | Not recommended | Yes — designed for heavy loads |
| Frost heave risk | Low (adjusts to minor shifts) | Low if frost walls are 30″+ deep |
| DIY friendly? | Moderate — achievable with planning | Difficult — pro recommended |
Gravel Pad: Pros, Cons & Pricing
A gravel pad is the most popular foundation for sheds and portable garages. It’s what we recommend for 80%+ of our builds. Here’s why:
Pros
- Superior drainage — water passes through, not around
- 60–75% cheaper than concrete
- Installs in one day
- Prevents moisture from wicking into the floor
- Can be removed or relocated
- Deters burrowing critters
Cons
- Not suitable for heavy vehicle traffic
- Needs edging/timber frame to contain stone
- May need occasional raking to re-level
Gravel Pad Pricing
- 8×8 pad: from $945
- 10×14 pad: from $1,200
- 12×20 pad: from $1,800
- 12×24 pad: from $2,100
- 14×28 pad: from $2,800
Prices include excavation, timber frame, weed barrier, and compacted ¾″ crushed stone. Full site prep pricing →
Concrete Slab: Pros, Cons & Pricing
A concrete slab is the premium foundation choice — necessary for modular garages and structures that need maximum load-bearing capacity.
Pros
- Supports heavy vehicles and equipment
- Extremely durable and permanent
- Doubles as the floor (no wood floor needed)
- Required by some townships for garages
- Resists frost heave with proper depth
Cons
- 3–5× more expensive than gravel
- Takes 3–5 days to install + curing time
- Poor drainage if not sloped properly
- Permanent — can’t relocate
- Can trap moisture under wood-floor structures
Concrete Slab Pricing
- 14×14 monolithic slab: from $4,230
- 20×24 with frost wall: from $7,500+
- 24×30 with frost wall: from $10,000+
- Concrete pier (per pier): from $200
Includes excavation, forming, reinforcement, pour, and finish. Full site prep pricing →
Which Should You Choose?
Common Foundation Mistakes
✘ Skipping the foundation entirely
Ground moisture rots the floor joists within 3–5 years. This is the #1 cause of premature shed failure.
✘ Using pea gravel or river rock
Round stones don’t compact. Your structure will settle unevenly. Always use angular ¾″ crushed stone.
✘ Building in a low spot
Water collects at the base during rain. Choose the highest, best-drained spot on your property.
✘ Placing a wood-floor shed directly on concrete
Moisture gets trapped between the wood floor and the slab, causing hidden rot. Use a gravel pad instead, or skip the wood floor.
✘ Forgetting weed barrier fabric
Weeds grow up through the gravel and into the base of your shed. Always lay fabric under the stone.
✘ Not checking setbacks before pouring concrete
A concrete slab is permanent. If it’s 2 feet too close to the property line, you can’t move it.
Frequently Asked Questions
Can I put a shed directly on the ground without a foundation?
You can, but we strongly advise against it. Without a foundation, ground moisture wicks directly into the floor joists, causing rot within a few years. Even a basic gravel pad adds 10–20 years to the life of your structure.
How thick should a gravel pad be for a shed?
We recommend 4–6 inches of compacted ¾″ clean crushed stone. The pad should extend 12 inches beyond the shed on all sides. A pressure-treated timber frame holds the stone in place.
Do I need a concrete slab for a garage?
Not always. Many of our portable garages (up to 14′ wide) work perfectly on a gravel pad. Modular garages built on site typically require a concrete pad because they don’t have a built-in wooden floor.
Can I use pea gravel instead of crushed stone?
No. Pea gravel is round and shifts under weight — it doesn’t compact well and can cause your structure to settle unevenly. Always use angular ¾″ clean crushed stone (also called #57 stone or modified stone).
How much does a gravel pad cost for a 12×20 shed?
A professionally installed gravel pad for a 12×20 shed (with 1-foot overhang on each side, so 14×22 actual pad) typically costs $1,500–$2,500 in our service area. The cost depends on ground conditions and access.
Can you arrange site prep for me?
Yes! We work with trusted local site prep partners who specialize in shed and garage foundations. We’ll coordinate everything so your pad is ready before delivery day.
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