Building Near Protected Trees: Planning Permission, TPOs and Foundation Design

A protected tree does not automatically prevent you from extending a house or developing a site.

It does, however, change how the project should be designed.

If a Tree Preservation Order applies, or important trees sit close to a proposed building, the planning layout, excavation, drainage, service routes, construction access and foundation design may all need to respond to the trees from the beginning.

That is very different from drawing the building first and asking an arboriculturist to make the trees fit around it afterwards.

AC Design Solution encountered this on the Marsden Manor new-build project in Prestbury. Planning permission for the replacement dwelling had already been obtained before our appointment, but the mature, tree-lined site was subject to a Tree Preservation Order and a substantial conditions package.

The arboricultural information identified 13 individual and six groups of B-category trees, together with one C-category tree. One retained tree, T6, had a minor approximately 3% Root Protection Area incursion associated with the development.

The project therefore had to progress with tree protection, planning conditions, technical design and construction requirements coordinated rather than treated as unrelated tasks.

The same project also presented poor ground conditions that made conventional shallow foundations unsuitable. That was a separate engineering issue, but it demonstrates an important principle: on a constrained site, tree protection and foundation design both need to be understood before construction details are fixed.

What Is a Tree Preservation Order?

A Tree Preservation Order (TPO) is made by a local planning authority to protect an individual tree, a group of trees or woodland where protection is considered appropriate in the interests of amenity.

A TPO can prohibit cutting down, topping, lopping, uprooting, wilfully damaging or wilfully destroying the protected tree without the appropriate authority or an applicable legal exception.

Importantly for construction projects, current government guidance also states that cutting protected roots is treated as prohibited tree work.

That means the planning issue is not limited to whether the trunk physically sits inside the proposed building footprint.

GOV.UK guidance on Tree Preservation Orders and trees in conservation areas

Can You Build Near a TPO Tree?

There is no national planning rule saying that development must always remain a fixed number of metres away from a TPO tree.

What matters is whether the proposed development can accommodate the tree appropriately and whether its roots, canopy and long-term condition can be protected.

This is why a search for “how close can I build to a TPO tree?” rarely has a useful answer expressed as one universal distance.

Different trees have different dimensions, condition, rooting environments and future growth potential.

The relevant constraint is usually established through arboricultural assessment rather than an arbitrary setback.

A planning authority can therefore approve development near protected trees where the design evidence demonstrates that the trees can be retained and protected satisfactorily.

Marsden Manor is a useful real example. The presence of protected mature trees did not make development impossible. It meant the site design and construction arrangements had to account for them.

What Is a Root Protection Area?

A Root Protection Area (RPA) is an area associated with a tree’s rooting environment that is identified during arboricultural assessment and used to inform the relationship between retained trees and development.

For planning purposes, it is an important design constraint.

It should not be misunderstood as simply drawing a circle around a trunk and assuming nothing can ever occur inside it.

The size and shape of the area, existing site conditions and the nature of proposed operations all matter.

The current published British Standard used for this work is BS 5837:2012 — Trees in relation to design, demolition and construction. As checked in August 2026, BSI still lists the 2012 edition as the current published standard, while a revised edition is in development.

BSI information on BS 5837

At Marsden Manor, the arboricultural assessment recorded a relatively small approximately 3% incursion into the RPA of retained tree T6.

The response was not to assume that any RPA overlap automatically made the project unacceptable. The development proceeded within the tree-protection measures incorporated into the wider approved strategy.

That is a much more realistic picture of building within or close to a root protection area: the specific effect needs to be assessed and justified.

What Does a Planning Application Near Protected Trees Need?

Where existing trees are likely to be affected by development, planning authorities commonly expect arboricultural information to influence the scheme.

Depending on the scale and site, that can include a tree survey, an Arboricultural Impact Assessment, a Tree Protection Plan and an Arboricultural Method Statement.

These documents perform different roles.

The tree survey establishes what is present.

The impact assessment considers how the proposed development interacts with retained and removed trees.

The protection plan shows how retained trees will be physically protected.

The method statement deals with sensitive construction operations where a written working methodology is needed.

For Marsden Manor, this principle was particularly important because Cheshire East’s local planning policy requires development to seek to retain and protect trees, woodlands and hedgerows and states that layouts should be informed by arboricultural assessment where relevant.

Cheshire East Policy ENV 6: Trees, hedgerows and woodland

The council’s policy specifically refers to BS 5837 where development is likely to affect existing trees.

This is useful E-E-A-T evidence for the Marsden Manor case because the advice in this article reflects the actual policy environment in which the project was being coordinated.

Real Project: Marsden Manor, Prestbury

Marsden Manor is a five-bedroom Georgian-style new-build residence at 54 Macclesfield Road, Prestbury.

AC Design Solution was appointed in 2022 after planning permission for the replacement house had already been secured.

Our role was therefore not simply to produce another planning concept. The client needed the approved scheme turned into coordinated technical information that could be constructed.

The appointment covered architectural design, structural engineering, Building Regulation drawings, M&E services, drainage, discharge of planning conditions and construction-stage coordination.

The tree constraint

The mature plot was subject to a Tree Preservation Order.

The arboricultural survey identified:

• 13 individual B-category trees;
• 6 groups of B-category trees;
• 1 C-category tree; and
• a minor approximately 3% RPA incursion affecting retained tree T6.

Planning conditions associated with the project also dealt with matters including ecology and tree protection.

AC Design Solution acted for the client on the condition-discharge programme rather than treating those requirements as something the contractor could resolve after starting work.

The structural constraint

Site investigation also identified poor ground conditions.

Those conditions made conventional shallow foundations unsuitable for the principal house.

The engineering response involved sheet piling to support excavation, with the permanent substructure and principal frame developed in reinforced concrete, including basement walls, columns and capping beams.

The detached garage, carrying different loads and following a different build sequence, was designed as a separate steel-framed structure.

Crucially, the project evidence does not establish that the protected trees caused the poor ground conditions. They were two separate site constraints.

What the project demonstrates is how a technically coordinated design needs to respond simultaneously to planning restrictions, arboriculture, soil conditions, structure, drainage and architecture.

That distinction is important when discussing foundation design near protected trees.

How Can Trees Affect Foundation Design?

There are two different engineering questions.

The first is:

How can the new foundations be built without unnecessarily damaging a retained tree?

The second is:

How should the foundations respond to ground movement where trees and shrinkable soils may interact?

Those questions overlap, but they are not identical.

Protecting the tree from excavation

Traditional strip or trench-fill foundations involve excavation.

If a proposed trench passes through important rooting areas, simply digging deeper does not solve the arboricultural problem. Deeper excavation can still sever roots.

The structural engineer and arboriculturist may therefore need to coordinate the foundation strategy.

Depending on the site, loads, soil conditions and tree constraints, alternative engineered solutions may be considered.

These might include deeper conventional foundations in suitable locations, piles and ground beams, or another project-specific structural arrangement.

There is no single “TPO foundation”.

The appropriate design comes from the actual tree information, site investigation and structural loads.

Protecting the building from soil movement

The second issue is ground behaviour.

Trees can influence moisture levels in some shrinkable clay soils. As moisture content changes, those soils can shrink or swell.

That does not mean every tree beside a house will cause subsidence.

The Royal Horticultural Society notes that most trees growing near buildings do not cause damage, although shrinkable clay soils can increase the risk in particular circumstances.

For structural design, factors can include soil classification, the shrinkage potential of the soil, tree species and water demand, mature tree height, distance between vegetation and foundations, and whether trees are being retained or removed.

How Deep Should Foundations Be Near Trees?

There is no universal foundation depth for building near trees.

This is one of the areas where generic online advice can become misleading.

Approved Document A provides structural guidance for England and explains that foundations in shrinkable clay need to take account of the influence of vegetation and trees.

It gives baseline minimum depths for strip foundations in low-, medium- and high-shrinkage clay, while also making clear that these depths may need to be increased where trees are nearby or satisfactory bearing ground is deeper.

Approved Document A: Structure

Those figures should not be lifted from the document and used as a foundation design without investigation.

The actual design needs to respond to the site.

Industry guidance such as NHBC Chapter 4.2 also considers soil shrinkage, tree water demand, mature height, tree distance and heave when assessing foundations near trees.

This is why foundation design near trees is an engineering task rather than a standard detail that can be copied from another extension.

Does a TPO Mean You Cannot Cut Any Roots?

Not necessarily, but root cutting should never be treated casually.

Government guidance states that cutting the roots of a tree protected by a TPO is treated as a prohibited activity requiring the authority’s consent unless an applicable exception applies.

This has direct implications for foundation trenches, drainage routes and services.

A drainage drawing that runs directly through an important rooting area can create the same coordination problem as a foundation.

The solution may therefore involve rerouting services, changing construction methods, adjusting levels or redesigning part of the scheme.

That is why arboriculture should influence architectural and engineering drawings before the project reaches site.

Does Planning Permission Override a TPO?

This needs a more precise answer than a simple yes or no.

Current GOV.UK guidance states that separate TPO consent is not required so far as tree work is necessary to implement a full planning permission.

For example, where full planning permission specifically requires a protected tree to be removed to construct the approved building, the TPO procedure contains an exception for that necessary work.

However, that does not create a general right to carry out unrelated pruning or additional tree works.

The position is also different where permission has expired, where only outline permission exists, where the tree work is not necessary to implement the permission, or where development is relying on permitted development rights.

Government guidance on TPOs and planning permission

For homeowners and developers, the practical lesson is simple:

Read the approved planning drawings, tree information and conditions together before carrying out any work to a protected tree.

TPO Trees and Conservation Area Trees Are Not the Same Thing

A Tree Preservation Order and conservation-area tree protection are related but separate controls.

A TPO protects the trees specified by the Order.

For trees in a conservation area that are not already protected by a TPO, Section 211 of the Town and Country Planning Act generally requires the local planning authority to receive six weeks’ notice before certain tree work is undertaken, subject to the statutory exceptions.

That notice period allows the authority to decide whether the tree should be protected by a TPO.

GOV.UK guidance for trees in conservation areas

Do not therefore assume that “there is no TPO” automatically means tree works can proceed without checking the conservation-area position.

What Happens During Construction?

Obtaining planning permission does not protect a tree from a poorly managed construction site.

Common risks can arise from excavation, compaction by heavy machinery, material storage, changes in levels and routing services through rooting areas.

Current tree-and-development guidance therefore places significant importance on construction protection.

At Marsden Manor, tree-protection measures were part of the planning and condition-discharge context rather than being left until construction was underway.

This is where the relationship between the arboricultural information and the construction drawings becomes important.

A Tree Protection Plan that shows an exclusion zone is only useful if the contractor’s access, scaffold, excavation, drainage routes and material storage can actually operate around it.

Good design tests those interfaces before site mobilisation.

Why Planning, Arboriculture and Structural Engineering Need to Be Coordinated

A project can fail technically even when each consultant has produced a correct document in isolation.

An arboriculturist may establish an RPA.

The architect may position an extension.

The structural engineer may specify a foundation.

The drainage designer may route a pipe.

If all four pieces of information are produced separately, they can conflict precisely where the site is most constrained.

At Marsden Manor, AC Design Solution’s architectural design, structural engineering, drainage and technical information were coordinated within one design process.

Structural openings and services could therefore be considered while the construction information was being developed rather than reconciled after contractors encountered clashes on site.

That is particularly valuable on a TPO site, where simply moving an excavation or drainage trench later may not be straightforward.

Building Regulations Near Trees

A Tree Preservation Order is a planning control.

It does not replace Building Regulations.

Where tree-related ground conditions influence the structural design, the foundation solution still has to satisfy the applicable structural requirements.

AC Design Solution’s Building Regulation drawings coordinate the wider technical package, while specialist structural drawings and calculations deal with load-bearing elements and foundation design where required.

Approved Document A remains the principal statutory guidance for structural requirements in England.

Planning approval for a building near protected trees should therefore not be confused with approval of the structural foundation design.

A Practical Sequence Before Designing Near Protected Trees

Before committing to the footprint of an extension or new building:

1. Check whether trees are protected. Review the local authority’s TPO information and conservation-area status.
2. Survey the trees early. Establish their location, size, condition and planning importance before fixing the building layout.
3. Establish the Root Protection Areas. Use the current arboricultural standard and site-specific assessment.
4. Develop the architecture around real constraints. Consider the building footprint, access, levels, drainage and service routes together.
5. Investigate the ground. Where foundation risk exists, obtain appropriate geotechnical information rather than assuming a standard footing.
6. Coordinate the structural solution with the arboriculturist. The foundation design must work for both the building and retained trees.
7. Submit the right arboricultural information with planning. The exact package depends on the authority and project.
8. Discharge relevant conditions before construction. Tree-protection and method-statement conditions can affect how and when work starts.

The order matters.

It is considerably easier to move a proposed wall during design than to discover after planning—or during excavation—that the proposed foundation conflicts with a tree that must be retained.

Building Near Protected Trees: The Marsden Manor Lesson

The main lesson from Marsden Manor is not that protected trees prevent ambitious construction.

They do not necessarily do so.

The lesson is that constraints need to become part of the design brief early enough to influence the project.

At Marsden Manor, the site had a TPO, mature trees, planning conditions, ecological requirements and poor ground conditions.

The tree assessment recorded retained vegetation and a minor RPA incursion. The planning-condition package then dealt with protection and environmental matters, while the engineering design addressed the site’s separate ground and structural requirements.

That is genuine coordination.

The result is a five-bedroom Georgian-style new-build residence progressing through construction with the architectural, structural, M&E, drainage and planning-condition information managed as one technical package.

For anyone building near protected trees, that is a more useful model than asking for a standard distance from a trunk or a standard foundation depth.

Frequently Asked Questions

How close can you build to a TPO tree?

There is no single national minimum distance that applies to every TPO tree. The relationship is normally assessed using arboricultural information, including the tree’s Root Protection Area, together with the design and construction methodology.

Can I build within a Root Protection Area?

Potentially, depending on the extent and nature of the proposed incursion and whether its effects can be satisfactorily assessed and managed. An RPA should be treated as a significant design constraint, not automatically as either an absolute exclusion zone or an area that can be ignored.

Marsden Manor included a minor approximately 3% RPA incursion affecting one retained tree, managed within the wider arboricultural and planning strategy.

Does a TPO stop planning permission?

No. A TPO does not automatically prevent planning permission being granted. The authority considers how the proposal affects the protected tree and whether it can be appropriately retained, protected or otherwise addressed through the planning process.

Do I need a tree survey for an extension near a protected tree?

It may be required where the proposed development could affect important or protected trees. Local validation requirements and policies vary, but arboricultural surveys and impact assessments are commonly expected where trees materially constrain a development.

Do foundations need to be deeper near trees?

Sometimes, particularly where shrinkable clay and tree-related moisture influence are relevant. But deeper foundations are not the universal solution. Soil conditions, tree species, tree size, distance, structural loads and arboricultural constraints all need to be considered.

Can protected tree roots be cut?

Government guidance treats cutting roots of a TPO-protected tree as prohibited tree work unless consent or a relevant statutory exception applies. Foundation and service excavations should therefore be coordinated before work begins.

Is a conservation-area tree automatically covered by a TPO?

No. Trees can be protected by a specific TPO or separately by the conservation-area provisions. For qualifying non-TPO trees in a conservation area, six weeks’ notice is generally required before certain tree works, subject to exceptions.

What British Standard applies when building near trees in 2026?

As checked in August 2026, BS 5837:2012 — Trees in relation to design, demolition and construction remains the current published standard. BSI is developing a revision, but the replacement had not yet been published at the time of this review.

Planning a Project Near Protected Trees?

The most useful time to identify a TPO or important tree constraint is before the architectural footprint and foundation strategy are fixed.

AC Design Solution can coordinate architectural design, planning information, structural engineering and Building Regulation drawings around the actual site constraints.

If you are considering an extension or new build close to protected trees, contact AC Design Solution to discuss the property before committing to the design.