How Much #57 Stone Under a 20x20 Deck?
A 20 by 20 foot deck covers 400 square feet. At 3 inches of #57 stone, plan on 3.70 cubic yards, or about 5.0 tons, which answers how much #57 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 1.35 tons per yard = 5.0 tons.
The crushed stone calculator does this for any size.
Related: How Much Pea Gravel Under a 20x20 Deck?
#57 stone needed by depth
| Depth | Cubic yards | Tons of #57 stone | Tons +10% |
|---|---|---|---|
| 2 in | 2.47 | 3.3 | 3.7 |
| 3 in | 3.70 | 5.0 | 5.5 |
| 4 in | 4.94 | 6.7 | 7.3 |
| 6 in | 7.41 | 10.0 | 11.0 |
Deck tips
Under a deck, stone is a weed and moisture barrier rather than a structural layer. Slope the soil away from the house, lay fabric and spread 2 to 3 inches of washed stone that drains quickly.
Related: How Much #57 Stone Under a 12x20 Deck?
Before the stone goes in
Remove sod and roots, level the area and slope it slightly for drainage. Install edging so the stone stays inside the footprint.
Ordering and delivery
Small dump trucks commonly carry around 5 to 10 tons and tri-axles more, but loads vary by truck and state, so ask the yard what fits in one trip. #57 is a washed stone of roughly 1/2 to 1 inch with few fines; it drains fast but stays a little loose on its own. Round up by about 10 percent for compaction and uneven ground.
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.
Common mistakes
The most frequent problem is ordering for the finished depth without allowing for compaction, which can shrink a loose layer by 10 to 20 percent. Another is skipping fabric on soft soil and watching the stone vanish into the mud over the first wet season. Spreading everything in one thick layer instead of compacted lifts also leaves a soft, rutted surface.
Questions people ask
How many tons of #57 stone under a 20x20 deck?
About 5.0 tons at 3 inches deep.
How many yards of #57 stone under a 20x20 deck?
About 3.70 cubic yards.
How many tons of #57 stone are in a cubic yard?
Roughly 1.35 tons for planning, but suppliers vary with stone size and moisture.
Should I put landscape fabric under the stone?
On soft or clay soil, a woven geotextile keeps stone from sinking into the dirt and makes the layer last longer.
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 Gravel Under a 20x20 Deck?
- How Much Crushed Stone Under a 20x20 Deck?
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