Fill Dirt vs Lava Rock: Size, Cost, and Which to Use
Fill Dirt runs about $5 per ton and Lava Rock about $90 per ton. Compare size, drainage, compaction, and which one to use.
Overview
Subsoil material free of organic matter, used for grading, filling, and raising elevation. Fill dirt is a lower-grade soil that lacks the nutrients of topsoil, making it ideal for structural and non-growing applications where settling must be minimized.
Lava rock is a lightweight, porous volcanic stone commonly used in landscaping. Its rough texture helps retain moisture while allowing airflow to plant roots.
Common Uses
Fill Dirt
- ✓ Grading
- ✓ Filling depressions
- ✓ Raising elevation
- ✓ Backfill
- ✓ Construction site prep
- ✓ Under slabs
Lava Rock
- ✓ Landscaping
- ✓ Garden beds
- ✓ Decorative ground cover
Pros & Cons
Fill Dirt
- + Very affordable — often cheapest material available
- + Compacts firmly for structural support
- + Does not decompose or settle like organic soil
- + Widely available from construction sites
- + Ideal base under gravel or concrete
- − Not suitable for growing plants
- − Must be free of debris and contaminants
- − May contain clay that drains poorly
- − Needs compaction in layers for stability
- − Quality varies widely between sources
Lava Rock
- + Very lightweight
- + Excellent moisture retention
- + Decorative appearance
- − Breaks down over time
- − Sharp edges
- − Can scatter easily
Cost Comparison
| Measure | Fill Dirt | Lava Rock |
|---|---|---|
| Per ton | $5 – $15 | $90 – $150 |
| Per cubic yard | $8 – $25 | $110 – $180 |
Sizes & Colors
Fill Dirt
Fine to coarse soil particles, free of organic matter like roots, grass, or leaves. Color ranges from tan to reddish-brown depending on local geology. "Clean fill" means free of debris, rocks larger than 3", and contaminants.
Lava Rock
Typically 3/4"–1.5" sizes. Red or black.
Published February 11, 2026
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