ProjectCalcThe standard
The relevant standard is BS 3882, Specification for topsoil. Approved Document C cites it directly in its site preparation provisions, which is how a garden materials question ends up inside a building regulation:
- AD C gives BS 3882:1994 as the reference for the specification of topsoil.
- It appears in the document's list of standards consulted for its site preparation guidance.
Two riders, both important. First, the edition cited by Approved Document C is the 1994 edition, because that is the edition the document was written against — and that edition is now Withdrawn. BSI catalogues BS 3882:2015 as the current edition (checked 22 September 2026), so the citation above is accurate to the source but is not what you would order to today. Second, we are not reproducing the grading, pH or contaminant limits from inside BS 3882: it is a paid publication and we could not read the primary text to check them, so they are not on this page.
Why a topsoil standard exists at all
"Topsoil" is sold by volume or by weight, and the word describes a position in the ground rather than a product. What a growing medium has to be depends on what is going to grow in it, and the same bag can be right for a shrub border and wrong for a lawn. A specification standard exists so that a buyer can state what they need and a supplier can be held to it — the same principle as a designated concrete mix.
That matters most on new-build sites, where the material under the garden may be subsoil, made ground or worse. Stripping and re-spreading site topsoil is normal practice; the question is what has happened to it in between, and whether it still meets the specification. That is where the standard does its work.
What the standard covers, in the terms a buyer needs
A topsoil specification is about the properties that decide whether plants can use it — how it is graded, how it drains, whether its chemistry is suitable for the planting, and whether it is free of the things you do not want in a garden (rubble, weed-propagating material, contaminants). Those are properties of the material, not of the delivery. The practical consequence is that a supplier should be able to tell you the specification of the topsoil they are delivering, in the standard's terms, rather than a bag volume and a price.
What this means for a calculation
- The volume and weight are ours to work out. Our topsoil calculator turns an area and a depth into a volume in cubic metres and a tonnage using a bulk density of 1.5 t/m³, with a settlement allowance.
- The bulk density is a planning figure, not a standard. It is a typical UK trade figure for screened topsoil, and it is labelled as an estimate — a wet or stony load will not weigh the same.
- The depth you need is a planting decision. How deep topsoil has to be depends on what is being grown and what is underneath. The calculator multiplies the depth you choose; it does not choose it for you.
- The specification is the supplier's to declare. Ask for it in the standard's terms before the lorry arrives, because a load that is wrong for the site is expensive to move twice.
Edition status — what the approved document cites, and what is current
An approved document names the edition of a standard that existed when it was written. That edition is not necessarily the current one. The table below sets out, for every standard this page relies on, the title as published, the edition the approved document cites, and the edition BSI catalogues today (22 September 2026). Where the cited edition is withdrawn, the page says so; where we could not confirm the replacement, no current edition is stated.
| Standard | Title as published | Edition cited by the approved document | Current edition (BSI) |
|---|---|---|---|
| BS 3882 | Specification for topsoil | BS 3882:1994 — cited by Approved Document C | BS 3882:2015 — Current (30 April 2015) |
Source: BSI catalogue records read at knowledge.bsigroup.com on 22 September 2026. Each title, designation, status and date in the last two columns was read from the BSI catalogue page for that standard.
Last verified 22 September 2026. Every requirement quoted on this page was read from the primary source listed below on that date, not from a summary. If a figure could not be confirmed in the primary source it is not on this page.
Where these figures come from
- Approved Document C: Site preparation and resistance to contaminants and moisture, 2013 edition — reference to BS 3882:1994, Specification for topsoil — GOV.UK publications, "Site preparation and resistance to contaminants and moisture: Approved Document C", checked 22 September 2026.
- BSI catalogue (“BSI Knowledge”) — product record for each standard listed above: title, current edition and status — knowledge.bsigroup.com, checked 22 September 2026.
Guidance only, not advice
This page is a plain-English summary of published regulations and standards, written to help you plan a job. It is not professional advice, it is not a substitute for the actual document, and it is not a building-control decision.
Building regulations are enforced by your local authority (or an approved inspector) and the facts of a particular job can change the answer. Confirm with your local building control before you start work, and where a job is structural, get it designed by a suitably qualified person. If this page and the source document disagree, the source document wins.