What is topsoil?
Topsoil is the top 15 to 30 cm of the ground, where most roots, worms and organic matter live. Bought topsoil is dug, screened to remove stones and roots, and sometimes blended with compost. It is the base for lawns and planting beds.
How deep should topsoil be?
Lawn top dressing
0.5 to 1 cm
New lawn from seed or turf
10 to 15 cm
New flower or vegetable beds
15 to 20 cm
Levelling a dip
30 cm or more
How does the calculation work?
Volume (m³) = area (m²) × depth (m) × 1.15
A new lawn of 50 m² at 10 cm: 50 × 0.1 = 5 m³. With 15% for settling, order 5.75 m³, roughly 7.5 tonnes.
Loose topsoil settles once it is watered and walked on. Ordering 10 to 20% more saves a second delivery when the surface sinks below the edges.
Grades of topsoil
Screened topsoil
Sifted to 10 to 20 mm. Smooth and easy to rake.
Best for lawns
Blended topsoil
Mixed with compost for extra nutrients.
Best for beds
Unscreened topsoil
Cheaper but full of stones and roots.
Best for bulk filling