If you are planning a building project or extension in London, Root Protection Areas, known as RPAs, play a key role in what you can and cannot do.
RPAs are designed to protect tree roots during construction. Ignoring them can lead to planning refusal, tree damage or long term structural issues.
At London Tree Survey Consultants, we help property owners and developers understand RPAs and plan projects that meet both planning and environmental requirements.
What Is a Root Protection Area (RPA)?
A Root Protection Area is the area around a tree that must be protected to ensure its survival.
It is calculated based on the size of the tree and represents the minimum area needed to protect the root system.
Within this area, the soil structure must remain stable and undisturbed.
RPAs are a key part of BS5837 tree surveys, which are often required for planning applications.
Why RPAs Matter for Building Projects
Tree roots are essential for stability, water uptake and overall health.
If roots are damaged during construction, it can lead to:
- Tree decline or death
- Increased risk of tree failure
- Structural instability
- Legal issues if the tree is protected
Local councils take RPAs seriously when assessing planning applications.
How RPAs Are Calculated
RPAs are calculated using a standard formula based on trunk diameter.
The result is shown as a circular or adjusted area around the tree.
A professional tree survey will:
- Measure the tree accurately
- Map the RPA on a site plan
- Identify constraints for development
London Tree Survey Consultants provides clear RPA plans to support planning applications.
What You Cannot Do Within an RPA
There are strict limits on what can happen within a Root Protection Area.
You should avoid:
- Excavation or digging
- Installing foundations
- Changing ground levels
- Storing materials or machinery
- Heavy foot traffic
These activities can compact soil and damage roots, which affects tree health.
How RPAs Affect Extensions and New Builds
RPAs can influence the design and layout of your project.
They may:
- Limit where extensions can be built
- Affect foundation design
- Require layout adjustments
- Reduce available build space
Ignoring these constraints often leads to planning refusal or costly redesigns.
Can You Build Within a Root Protection Area?
In some cases, limited work may be allowed within an RPA, but it requires careful planning.
Solutions may include:
- Special foundation systems
- Raised structures
- Minimal dig construction methods
- Protective ground systems
These methods reduce impact on roots but must be approved by the local authority.
Tree Protection Measures During Construction
If building work is approved near trees, protective measures are required.
These may include:
- Protective fencing around RPAs
- Ground protection systems
- Controlled access routes
- Ongoing supervision by a tree consultant
These steps help ensure the tree remains safe throughout the project.
The Role of a BS5837 Tree Survey
A BS5837 tree survey is often required when submitting a planning application.
This report includes:
- Tree identification and condition
- RPA calculations
- Tree constraints plan
- Recommendations for protection
London Tree Survey Consultants prepares detailed BS5837 reports to support planning approval and reduce delays.
Common Planning Issues Related to RPAs
Projects can face delays if RPAs are not properly considered.
Common issues include:
- Building too close to protected trees
- Lack of tree survey information
- Poor site planning
- Failure to include protection measures
Addressing these early improves your chances of approval.
How to Plan a Project Around Trees
To avoid problems, it is important to plan early.
Best practice includes:
- Carrying out a tree survey before design begins
- Understanding all RPAs on site
- Designing around tree constraints
- Consulting with a tree specialist
- Submitting clear and accurate reports
London Tree Survey Consultants works with property owners and developers to create practical solutions that meet planning requirements.
Why Professional Guidance Is Important
RPAs can be complex, especially on sites with multiple trees.
A professional tree consultant will:
- Provide accurate measurements
- Create clear site plans
- Recommend suitable construction methods
- Help you avoid costly mistakes
This ensures your project progresses smoothly.
Conclusion
Root Protection Areas are a critical part of building projects in London. They protect trees, influence design and play a key role in planning decisions.
Understanding RPAs early helps avoid delays, reduces risk and supports successful project outcomes.
If you are planning a development or extension, London Tree Survey Consultants can guide you through every stage and ensure your project meets all tree-related requirements.