Paver Calculator: Don’t Let Your Patio Sink
Paver Calculator: Don’t Let Your Patio Sink
A paver patio is a “flexible pavement system.” Unlike concrete, it moves with the earth. But if the layers underneath aren’t thick enough, it will move too much, creating ruts, puddles, and tripping hazards.
The secret isn’t the stone; it’s the dirt. Use this engineering-grade tool by ShockTrail to calculate the tons of rock you need to hide underground.
The Hardscape Estimator
Calculate your Paver Count, Gravel Base (Yards), and Sand (Tons) in one click.
Paver & Patio Estimator
Stone • Gravel Base • Sand*Gravel calculation includes 20% compaction factor.
PART 1: The Anatomy of a Paver Job
You aren’t just buying bricks. You are building a 3-layer cake.
[Image of paver cross section layers]- Layer 1: Geotextile Fabric. Separates the native soil from your gravel. Prevents the gravel from sinking into the mud over time.
- Layer 2: Road Base (CR-6). A mix of 3/4″ stone and stone dust. This must be 4 to 6 inches deep and compacted until it feels like concrete.
- Layer 3: Bedding Sand. A 1-inch layer of clean, sharp sand (C-33). This is for leveling the pavers.
- Layer 4: The Pavers. The visible stone.
- Layer 5: Polymeric Sand. The “glue” that goes between the joints to stop weeds.
The Compaction Factor (20% Loss)
When you order 5 yards of gravel and run a plate compactor over it, it compresses down to about 4 yards. You lose volume to density.
ShockTrail Rule: Always order 20% more gravel than the volume calculation suggests. If you run short, you have to stop working and pay for another delivery fee ($150+).
PART 2: Real-World Case Studies
The depth of your base depends on what you are putting on top. Cars are heavier than lawn chairs.
Case Study 1: The Backyard Patio (Pedestrian Load)
The Project: A 15ft x 20ft patio for a fire pit and grill.
The Math:
- Area: 300 sq ft.
- Base Depth: For walking only, 4 inches of compacted gravel is sufficient.
- Volume: (300 × 0.33 ft) = 100 cubic ft.
- Compaction: 100 × 1.20 = 120 cubic ft = 4.5 Cubic Yards of Gravel.
- Pavers: 300 sq ft + 5% waste = 315 sq ft of Holland Stone.
Case Study 2: The Paver Driveway (Vehicle Load)
The Project: A 20ft x 40ft driveway. This will hold SUVs weighing 6,000 lbs.
The Math:
- Area: 800 sq ft.
- Base Depth: You need a minimum of 8 to 10 inches of base for vehicles.
- Volume: (800 × 0.83 ft) = 664 cubic ft.
- Compaction: 664 × 1.20 = 800 cubic ft = 30 Cubic Yards of Gravel. (That is 2-3 dump trucks!).
- Pavers: You need 80mm thick pavers (standard is 60mm) to handle the torque of turning tires.
Case Study 3: The Circular Fire Pit (Complex Cuts)
The Project: A 12ft diameter circular patio kit.
The Math:
- Area: π × r² = 3.14 × 6² = 113 sq ft.
- Waste Factor: If you are cutting square pavers into a circle, you will have massive waste. Add 20% to 25% for cuts.
- Base Extension: The gravel base should extend 6 inches past the edge of the pavers to prevent the edge from collapsing. So you are prepping a 13ft circle.
PART 3: Paver Materials (Concrete vs. Clay)
What are you buying?
| Material | Cost | Durability | Notes |
|---|---|---|---|
| Concrete Pavers | $3 – $6 / sq ft | High (8000 PSI) | Most common. Fades over time (UV). |
| Clay Brick | $6 – $12 / sq ft | Extreme (Color never fades) | Classic look. Brittle (harder to cut). |
| Natural Stone (Flagstone) | $15 – $25 / sq ft | Variable | Irregular shapes make installation slow. |
PART 4: Polymeric Sand (The Magic Glue)
In the old days, we swept regular sand into the cracks. It washed away, and weeds grew.
Today, we use Polymeric Sand. It contains polymers that activate with water, turning the sand into a hard, rubbery grout.
- Coverage: One 50lb bag covers ~50-75 sq ft for standard pavers (narrow joints).
- Warning: You must blow every speck of dust off the paver surface before watering, or the polymers will stain your patio white forever.
PART 5: Edge Restraints
If you don’t contain the edges, the pavers will “drift” into the grass over time. You need:
- Plastic Edging: Spiked into the gravel base with 10-inch landscaping spikes.
- Concrete Bond Beam: A troweled wedge of concrete hidden under the grass/mulch.
Frequently Asked Questions (FAQ)
Can I put pavers over concrete?
Yes, using a “Sand Set” or “Bitumen Set” method. However, you must drill drainage holes in the old concrete slab first, or water will trap between the layers and freeze, popping the pavers up.
How deep should I dig?
Total Excavation = Base Depth (6″) + Sand Depth (1″) + Paver Thickness (2.5″) = 9.5 inches deep.
Do I need a plate compactor?
Yes. You cannot compact 4 inches of gravel with a hand tamper. Rent a gas-powered plate compactor (~$80/day). It is essential for interlock.
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