How Much Crushed Stone Under a 20x20 Deck?
A 20 by 20 foot deck covers 400 square feet. At 3 inches of crushed stone, plan on 3.70 cubic yards, or about 5.2 tons, which answers how much crushed stone under a 20x20 deck.
Volume and tonnage calculator →The math
- Area: 400.0 sq ft.
- Depth in feet: 3 ÷ 12 = 0.250 ft.
- Cubic yards: 400.0 × 0.250 ÷ 27 = 3.70 yd³.
- Tons: × about 1.4 tons per yard = 5.2 tons.
The crushed stone calculator does this for any size.
Related: How Much Pea Gravel Under a 20x20 Deck?
Crushed stone needed by depth
| Depth | Cubic yards | Tons of crushed stone | Tons +10% |
|---|---|---|---|
| 2 in | 2.47 | 3.5 | 3.8 |
| 3 in | 3.70 | 5.2 | 5.7 |
| 4 in | 4.94 | 6.9 | 7.6 |
| 6 in | 7.41 | 10.4 | 11.4 |
Stone for a deck
Gravel under a deck blocks weeds, keeps the ground from turning to mud and lets water drain. Lay landscape fabric first, then about 2 to 3 inches of stone; there is no need to compact it the way you would a driveway base.
Related: How Much #57 Stone Under a 20x20 Deck?
Prep
Remove sod and roots, level the area and slope it slightly for drainage. Install edging so the stone stays inside the footprint.
Getting it delivered
Most quarries and landscape yards deliver by the ton; ask whether there is a minimum and a delivery fee, and where the driver can dump without damaging your lawn. Crushed stone has angular faces that lock together under a compactor, which is why it holds a pad shape. Ask your supplier for their own tons-per-yard number, since stone source and moisture change it.
Tools for the job
A flat shovel, a steel rake, a wheelbarrow and a rented plate compactor cover most residential pads. A landscape rake or the back of a rake levels the top layer, and a long straightedge or a level string shows high and low spots before the final pass.
Measuring the area
Use a long tape and measure each side twice. If the ground slopes, measure depth at the high and low ends and average them. Irregular outlines can be broken into simple rectangles, triangles and circles; add the pieces for the total square footage before converting to tons.
Questions people ask
How many tons of crushed stone under a 20x20 deck?
About 5.2 tons at 3 inches deep.
How many yards of crushed stone under a 20x20 deck?
About 3.70 cubic yards.
How many tons of crushed stone are in a cubic yard?
Roughly 1.4 tons for planning, but suppliers vary with stone size and moisture.
Do I need to compact it?
Yes for anything that carries weight. Compact in lifts of a few inches with a plate compactor.
Related guides
- Gravel Under a Deck: Weeds, Drainage, and Depth
- How Much Does a Ton of Gravel Cover? Depth Chart
- Tons to Cubic Yards for Gravel: Conversion Chart
- Crushed Stone vs Gravel: Differences and Best Uses
- Geotextile Fabric for Driveways: Woven vs Nonwoven and How Much You Need
- Compacting a Driveway Gravel Base in Lifts
- How Much Pea Gravel Under a 16x20 Deck?
- How Much Gravel Under a 20x20 Deck?
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