What's the Difference?
The distinction is simple. Screened topsoil has been passed through a mechanical screen (typically a trommel — a rotating cylindrical mesh) to remove stones, roots, lumps of clay, and debris. Unscreened topsoil hasn't — it comes as-dug from the source site.
Both start as the same material. Screening is a processing step that improves the physical consistency of the soil. It doesn't change the nutrient content, pH, or organic matter — just removes the bits you don't want.
What Screening Actually Removes
A typical 10mm screen removes:
- Stones and gravel larger than 10mm
- Root fragments and twigs
- Clay lumps and compacted clods
- Debris (plastic, brick fragments, glass)
- Large organic matter (uncomposted leaves, bark)
What passes through is a consistent, fine-textured soil that's easy to work with, rakes to a smooth finish, and provides an even surface for turf or seed.
Some suppliers offer different screen sizes. A 10mm screen is standard for garden use. A 20mm screen is coarser (and cheaper) — suitable for general landscaping but not for lawns. A 5mm screen is very fine and usually only available at premium prices for specialist applications.
When to Use Screened Topsoil
Always Use Screened For:
- New lawns: Stones and lumps under turf create bumps, and grass seed needs fine, even soil contact to germinate. This is the one application where screened is genuinely essential. See our lawn preparation guide
- Raised beds for vegetables: Stones in the soil cause root crops to fork and make digging difficult. Our raised bed guide covers what to look for
- Seed beds and nursery areas: Fine soil structure is critical for seed germination
- Top-dressing existing lawns: Any top-dressing material must be stone-free to avoid damaging mower blades
Screened Is Preferred For:
- Flower borders: Not strictly essential, but makes planting and maintenance easier
- Final grading: If appearance and finish matter, screened gives a cleaner result
When Unscreened Is Fine
Use Unscreened For:
- Backfilling trenches or foundations: No one sees it, and the stones actually improve drainage
- Building up levels: If you're raising the level of an area by 200mm+ and will be putting screened topsoil on top, use cheaper unscreened for the bulk of the fill
- Under paving or decking: The soil beneath hard landscaping doesn't need to be stone-free
- Large-scale landscaping: Commercial projects often use unscreened for general earthworks, with screened only in the final 100-150mm
- Rough planting areas: Trees, hedges, and large shrubs don't care about stones in the soil
Cost Comparison
Screened topsoil typically costs 30-50% more than unscreened. The exact premium depends on the supplier and your location, but as a rough guide:
| Type | Bulk Bag Price (approx.) | Loose Load per m³ (approx.) |
|---|---|---|
| Screened | £70-90 | £30-45 |
| Unscreened | £45-65 | £20-30 |
For large projects, a smart approach is to use unscreened for the bulk fill and screened for the top layer. On a project needing 10 cubic metres of topsoil at 150mm depth across 66 square metres, you might use 6m³ of unscreened at the bottom and 4m³ of screened on top — saving £80-150 compared to using screened throughout.
Quality Matters More Than Screening
It's worth noting that screening alone doesn't make topsoil good. You can have perfectly screened topsoil that's the wrong pH, too heavy in clay, contaminated, or nutrient-poor. Conversely, you can have unscreened topsoil that's beautiful, fertile soil with a few stones in it.
The quality indicators that actually matter for plant growth are:
- Texture: Loam or sandy loam is ideal. Heavy clay is problematic even when screened
- pH: Between 5.5 and 7.5 for most garden plants
- Organic matter: 5-15% for healthy soil biology
- Contaminants: Free of heavy metals, hydrocarbons, and other pollutants
- BS3882 certification: The British Standard for topsoil covers all of the above. See our BS3882 guide for details
If you're spending money on topsoil, the BS3882 certification is a more important quality marker than whether it's been screened. A BS3882 certified unscreened topsoil is a better product than an uncertified screened one in most applications.
How to Check What You've Received
When your topsoil delivery arrives, check it before spreading:
- Grab a handful and squeeze it. It should hold together when compressed but crumble when you poke it. If it stays in a solid lump, it's too clay-heavy. If it falls apart immediately, it's too sandy
- Look for stones. In screened topsoil, you shouldn't see any stones larger than the stated screen size (usually 10mm)
- Smell it. Healthy topsoil smells earthy. A sour, sulphurous, or chemical smell indicates contamination or anaerobic conditions
- Check the colour. Medium to dark brown is ideal. Very dark (almost black) soil may have excessive organic matter. Very pale soil may be subsoil sold as topsoil
If what arrives doesn't match what you ordered — particularly if "screened" topsoil is clearly full of stones — contact the supplier immediately. Reputable suppliers will replace it. This is another reason to order from established, reviewed suppliers.