How much topsoil for a new lawn

How deep for a new lawn

A seeded or sodded lawn wants 4–6 in of topsoil over the subgrade: 4 in on decent existing soil that you have loosened with a tiller, 6 in on clay, gravel or the compacted fill left behind a new house. Grass roots reach 6 in and deeper in good soil, and the depth you give them sets how well the lawn handles a dry August.

Top-dressing an existing lawn is a different job: ¼–½ in of screened topsoil or compost raked in after aerating. Set the depth field to 0.5 for that.

Screened topsoil, garden mix, or fill

Ask what the yard is selling. Screened topsoil has been run through a mesh to take out stones, roots and clods; it rakes easily and is the usual choice under a lawn. A garden or lawn mix is topsoil blended with compost or sand, lighter and richer. Fill dirt is unscreened subsoil, often with rocks and clay; it is for raising grades, not growing grass, and belongs under the topsoil, never on top. Look at the pile before it is loaded: dark, crumbly, few stones, no sour smell.

Measuring and ordering

1. Measure the lawn’s length and width; break an L-shaped yard into two rectangles and run the sheet twice, or add the areas with the square footage calculator.
2. Set the depth: 4 in on workable soil, 6 in on clay or fill, 0.5 in to top-dress.
3. Keep the 5 % settling allowance, and add another 5 % if the ground has been freshly tilled: loose soil settles about 10 % as it is watered and walked on.
4. Read the weight. The sheet uses 1.1 tons per cubic yard for dry screened topsoil; wet soil weighs a third more.
5. Edit the bulk price to the yard’s quote per cubic yard with delivery, and order in whole yards, rounded up.
6. Ask for the drop where the wheelbarrow route is shortest, on a tarp or the driveway.

Grade, spread and settle

Before the soil arrives, rough-grade the subgrade so it falls away from the house at about ¼ in per foot for the first 6–10 ft. Take out rocks, roots and debris, and loosen the top 2–3 in with a tiller so the new soil binds to it instead of sitting on it as a separate layer.

Spread with a wheelbarrow and a rake, working from the far corner toward the pile. Level it with a landscape rake or a straight board; a lawn roller half-filled with water firms it enough to walk on without compacting it. Water the graded soil and let it settle for a few days before seeding: the low spots show up, and the 10 % you allowed is what fills them.

Weight and the pickup

Topsoil is heavy. A cubic yard of dry screened topsoil weighs about 1.1 tons and a wet one about 1.5, so a level full-size pickup bed holds 2 cu yd by volume but that load is 2–3 tons, well above a half-ton truck’s payload. Plan on one yard per trip, or have it delivered: a tandem dump truck brings 10–14 cu yd in one drop, and for a lawn of any size the delivery fee is cheaper than a day of trips.

Common mistakes

• Spreading topsoil over compacted subsoil without loosening it. The layers don’t bond and the lawn dries out at the seam.
• Grading toward the house. Check the slope with a level on a long board before the soil goes down.
• Buying fill and calling it topsoil. Fill is for raising grades; grass needs screened soil on top.
• Seeding straight after spreading. Water, wait, fill the low spots, then seed.
• Loading a half-ton pickup with two yards. Check the payload sticker in the door; it is lower than you think.