What is BS 8640:2025 - Structural and supported soils for trees in hard landscapes guide about?
There is a UK-wide push for more urban trees but very little information available on suitable growing media, including structural soils.
To plug that gap, and support more sustainable urban development, BS 8640:2025 gives guidance on the most successful growing medium in different situations so trees grown in hard landscapes are more likely to live long, healthy lives.
Who is BS 8640:2025 - Structural and supported soils for trees in hard landscapes guide for?
Users of this standard might include:
- Environmental engineers;
- local planning authorities;
- community forests;
- tree nurseries;
- architects;
- landscape architects;
- developers; and
- landscape contractors.
What does BS 8640:2025 - Structural and supported soils for trees in hard landscapes guide cover?
BS 8640:2025 gives guidance on water storage, filtration, hydraulic conductivity, fertility, pH, load-bearing capacity (where applicable), volumes, depth of material and stratification of soils to support tree growth in hard landscapes. It also covers how the material is to be placed and gives guidance on irrigation.
BS 8640:2025 also examines the role of tree soils in the filtration of water and sequestration of carbon; and gives guidance on root management and on the different soil media for establishing trees in the hard landscape.
NOTE: BS 8640:2025 does not replace the need for a qualified structural engineer to assess the location of the tree pit in relation to other structures; nor does it cover tree species selection. It does not detail the structures that might be used for irrigation, nor structures that might provide support for the tree or pavement. However, it does provide advice on appropriate soil volume required by different-sized species at maturity. For soil quality and handling, see BS 3882 and BS 8601.Tree species selection is covered by BS 8545.
Why should you use BS 8640:2025 - Structural and supported soils for trees in hard landscapes guide?
- Utility: BS 8640:2025 gives accessible, current, objective and expert guidance on the best soil media for establishing trees in hard landscapes. For example, it covers what’s going to support the tree (weight bearing volume) and the right medium to allow drainage while also being structural (i.e. to support cement pavements, to ensure trees do not to interfere with services etc.) It gives solutions to complex situations and outlines options for achieving successful installations where little reliable guidance has previously existed.
- Sustainability and climate resilience: Healthy urban trees deliver critical ecosystem services such as shade, carbon sequestration, air purification, and habitat creation. By providing measured solutions to the complex demands of urban tree planting, BS 8640 enables organizations to take sensible action to address the climate emergency and realize the benefits of sustainable urban development.
- Specificity: BS 8640:2025 give sufficient detail to allow environment engineers to engineer structural soils that are fit for purpose.
- Confidence: BS 8640:2025 gives local authority planners confidence that appropriate volumes of the specified growing media will be used and applied. It gives community foresters confidence that trees grown in hard landscapes will be more likely to live long, healthy lives. It gives tree nurseries a better understanding of the demands placed on a tree in the transition from nursery to structural soils, so they can build confidence in how to ensure tree longevity. And it gives landscape architects confidence that designed hard landscapes can support long-term tree survival.
- Cost efficiency: By improving tree health and survival rates, BS 8640 helps maximize the return on investment of urban tree planting.
