How much topsoil to put under sod
Area times depth. Penn State Extension's guide to establishing a lawn works a 1 to 2 inch layer of compost or peat into the top 4 to 6 inches of soil before the sod goes down, and this page starts at the 2 inch end. A lawn 50 by 40 feet is 2,000 square feet; at 2 inches that is 333.33 cubic feet, 12.35 cubic yards, ordered as 12.5.
No waste is added to the soil. The waste on this page is the sod cut off at the edges and thrown away; the ground under the lawn is the same size however the sod is cut. The same lawn takes 825 slabs of sod, five pallets, and they are on the list beside the soil.
How deep
Two different jobs share the word topsoil. Working compost into the soil you have is 1 to 2 inches (Penn State) — Purdue Extension writes it as 1 to 3 cubic yards per 1,000 square feet, mixed 6 to 8 inches deep. Rebuilding soil that a builder scraped away is far more: Penn State says good turf needs at least 4 to 6 inches of topsoil, and Purdue puts it at about 19 cubic yards for 6 inches over 1,000 square feet.
| Depth | Per 1,000 ft² | This lawn, 2,000 ft² |
|---|---|---|
| 1 in | 3.09 yd³ | 6.17 yd³ |
| 2 in | 6.17 yd³ | 12.35 yd³ |
| 4 in | 12.35 yd³ | 24.69 yd³ |
| 6 in | 18.52 yd³ | 37.04 yd³ |
A soil test is what says which job yours is. The depth is a box under Assumptions: type the depth your test or your landscaper gives, and 0 leaves the soil out.
Buying it
By the cubic yard, delivered, in quarter yards: 12.35 is ordered as 12.5. The reference price is $35.00 a yard and $85.00 for the delivery, our estimates for bulk topsoil — type your yard's. A small lawn may be cheaper in bags; the next link carries this lawn to the topsoil calculator, which compares the two.
Spread it before the sod is delivered, not the same morning: the soil should be raked smooth, firm enough to walk on, and dry to slightly moist when the sod goes down — Penn State says never to lay sod on wet soil. We are not connected with any supplier named here.