Topsoil
Topsoil is the upper layer of a soil profile, usually darker in colour (because of its higher organic matter content) and more fertile than subsoil, and which is a product of natural
biological and environmental processes. Ref The HS2 London-West Midlands Environmental Statement, Glossary of terms and list of abbreviations, DETR 2013.
Topsoil is typically between 5 - 20 cm (2 - 8 inches) deep. It can also be measured as the depth from the surface level to the subsoil, i.e. the distance to the first densely-packed layer of soil.
The topsoil is where the majority of the biological soil activity occurs, as it contains the highest concentration of organic matter and microorganisms, due to decomposition from animals, plants, and so on. The topsoil contains the highest concentration of plant roots, as plants acquire the majority of their nutrients from the topsoil layer.
The main elements that make up topsoil composition are:
The soil’s strength and bearing capacity depends on its skeletal structure and decreases with the presence of organic matter.
Water run-off results in minerals from the topsoil migrating down into the subsoil which can lead to mineral deficiencies in the topsoil. The knock-on effect of this is that roots have to dig deeper for nutrients. During construction it can be necessary to strip topsoil, although it should be considered that by exposing the subsoil, the rate of erosion of soil minerals increases.
Construction work can lead to the organic matter of topsoil condensing and settling in different ways, such as in roadbeds and foundations.
[edit] Find out more
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Call for greater recognition of professional standards
Chartered bodies representing more than 1.5 million individuals have written to the UK Government.
Cutting carbon, cost and risk in estate management
Lessons from Cardiff Met’s “Halve the Half” initiative.
Inspiring the next generation to fulfil an electrified future
Technical Manager at ECA on the importance of engagement between industry and education.
Repairing historic stone and slate roofs
The need for a code of practice and technical advice note.
Environmental compliance; a checklist for 2026
Legislative changes, policy shifts, phased rollouts, and compliance updates to be aware of.
UKCW London to tackle sector’s most pressing issues
AI and skills development, ecology and the environment, policy and planning and more.
Managing building safety risks
Across an existing residential portfolio; a client's perspective.
ECA support for Gate Safe’s Safe School Gates Campaign.
Core construction skills explained
Preparing for a career in construction.
Retrofitting for resilience with the Leicester Resilience Hub
Community-serving facilities, enhanced as support and essential services for climate-related disruptions.
Some of the articles relating to water, here to browse. Any missing?
Recognisable Gothic characters, designed to dramatically spout water away from buildings.
A case study and a warning to would-be developers
Creating four dwellings... after half a century of doing this job, why, oh why, is it so difficult?
Reform of the fire engineering profession
Fire Engineers Advisory Panel: Authoritative Statement, reactions and next steps.
Restoration and renewal of the Palace of Westminster
A complex project of cultural significance from full decant to EMI, opportunities and a potential a way forward.
Apprenticeships and the responsibility we share
Perspectives from the CIOB President as National Apprentice Week comes to a close.
The first line of defence against rain, wind and snow.
Building Safety recap January, 2026
What we missed at the end of last year, and at the start of this.