Fill dirt and topsoil are fundamentally different materials with different purposes. Using the wrong one can cost you time, money, and potentially cause structural problems. Here's everything you need to know to make the right choice.
What Is Fill Dirt?
Fill dirt is subsoil — the layer of earth beneath the topsoil. It has minimal organic matter, few nutrients, and doesn't support plant growth well. What it does do is compact tightly, resist settling, and provide structural stability. Fill dirt typically costs $10-15 per cubic yard delivered.
Fill dirt is composed primarily of clay, sand, and rock particles in varying ratios depending on the source. Clean fill dirt has been screened to remove large rocks, roots, and debris, but it's not a growing medium — it's a building medium.
What Is Topsoil?
Topsoil is the top 4-12 inches of earth that contains organic matter, nutrients, microorganisms, and the biological activity that supports plant growth. When you want grass, gardens, flowers, or any vegetation to grow, you need topsoil. Screened topsoil typically costs $17-20 per cubic yard delivered.
Quality topsoil has a loose, crumbly texture that retains moisture while allowing drainage. It's darker in color than fill dirt due to the organic content. Screened topsoil has been processed to remove rocks and debris for a consistent, workable texture.
When to Use Fill Dirt
Use fill dirt any time you need to change the elevation or grade of land and don't need anything to grow on the surface. Common fill dirt applications include filling holes and low spots in your yard, backfilling swimming pool removals, raising land elevation, backfilling behind retaining walls, filling foundation trenches, general site grading and preparation, and creating berms or mounds.
The key principle: if the dirt will be under something (a patio, driveway, building, or additional soil layers), use fill dirt. It's cheaper, more stable, and purpose-built for structural applications.
When to Use Topsoil
Use topsoil any time you need plants, grass, or vegetation to grow. Common topsoil applications include preparing for sod installation (4-6 inches recommended), creating or renovating garden beds, establishing new lawns from seed, repairing bare or thin patches in existing lawns, building raised garden beds, erosion control with vegetation, and landscape grading where aesthetics matter.
The key principle: if something needs to grow on it, use topsoil.
When to Use Both
Many projects require both fill dirt and topsoil. The most common scenario is using fill dirt to bring the area to rough grade (within 4-6 inches of final elevation), then topping with screened topsoil for the growing layer.
For example, if you're filling a pool and want a lawn over it, you'd use 90% fill dirt (compacted in lifts) and top with 4-6 inches of topsoil. If you're leveling a yard that's 12 inches low, use 6-8 inches of fill dirt and 4-6 inches of topsoil.
What About Structural Fill?
Structural fill ($20-23/yard) is a step above standard fill dirt. It's engineered to meet specific compaction and stability requirements for load-bearing applications. Use structural fill under foundations, driveways, slabs, and anywhere that supports weight or requires engineering inspection. Standard fill dirt is fine for non-structural applications like pool fills and yard leveling.
Cost Comparison
In Texas (DFW area), clean fill dirt starts at $10 per cubic yard delivered, screened topsoil at $17 per yard, and structural fill at $20 per yard. In Colorado (Denver metro), fill dirt starts at $15 per yard, topsoil at $20 per yard, and structural fill at $23 per yard. All prices include dump truck delivery. Minimum order is 10 cubic yards.
The Bottom Line
Choose fill dirt for anything structural: holes, grade changes, backfill, pool removal. Choose topsoil for anything that grows: lawns, gardens, flower beds. Use both when you need to fill deep and grow on top. When in doubt, text us at (512) 616-1820 and describe your project — we'll recommend exactly what you need and how much.