How Much #57 Stone Under a 12x20 Deck?
How much #57 stone under a 12x20 deck: about 3.0 tons at 3 inches deep. The area is 240 square feet, which is 2.22 cubic yards at that depth.
Volume and tonnage calculator →The math
- Area: 240.0 sq ft.
- Depth in feet: 3 ÷ 12 = 0.250 ft.
- Cubic yards: 240.0 × 0.250 ÷ 27 = 2.22 yd³.
- Tons: × about 1.35 tons per yard = 3.0 tons.
The crushed stone calculator does this for any size.
Related: How Much Pea Gravel Under a 12x20 Deck?
#57 stone needed by depth
| Depth | Cubic yards | Tons of #57 stone | Tons +10% |
|---|---|---|---|
| 2 in | 1.48 | 2.0 | 2.2 |
| 3 in | 2.22 | 3.0 | 3.3 |
| 4 in | 2.96 | 4.0 | 4.4 |
| 6 in | 4.44 | 6.0 | 6.6 |
Building the deck base
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 10x10 Deck?
Prep
Remove sod and roots, level the area and slope it slightly for drainage. Install edging so the stone stays inside the footprint.
Buying the stone
If you haul it yourself, a typical half-ton pickup should carry only about half a cubic yard of stone, well under what the bed looks like it can hold. #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. The scale ticket is the real weight; tons per yard here is a planning figure.
Measuring the area
Measure length and width in feet at a few points and use the largest figures, since real sites are rarely square. For odd shapes, split the area into rectangles and circles, work out each one and add them together. Depth is the number most people underestimate: drive a stake, run a level string and measure down to the dug-out surface in several spots.
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 12x20 deck?
About 3.0 tons at 3 inches deep.
How many yards of #57 stone under a 12x20 deck?
About 2.22 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 12x20 Deck?
- How Much Crushed Stone Under a 12x20 Deck?
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