Arboricultural Impact Assessment (AIA)
Planning-ready BS 5837 assessments that identify how your development interacts with trees — clear constraints, practical mitigation and predictable outcomes.
Designs evolve, layouts shift and tree constraints become clearer with every stage. An AIA gives planners and design teams the exact evidence they need to progress without unnecessary redesigns or delays.
Design meets trees — and certainty keeps projects moving
Conflicts with root protection areas, shading, overhang or retention categories can stall progress at the wrong moment.
A focused AIA shows how your layout interacts with every relevant tree and sets out reasonable, proportionate solutions.
What is an Arboricultural Impact Assessment (AIA)?
An AIA evaluates how a proposed development affects trees on and around the site.
Under BS 5837, it assesses:
- root protection areas (RPAs)
- above-ground constraints (crown spread, shading, future pressure)
- retention categories
- construction impact and design conflicts
- access, storage and working areas
- tree retention feasibility
- required mitigation
The result is a clear, planning-ready assessment showing how tree constraints have been considered and managed.
The AIA Process
| Step | Description |
|---|---|
| 1. Initial Review | Share the layout, site plan and any existing survey data. |
| 2. Site Survey | Assessment of tree condition, RPAs, crown spread and constraints. |
| 3. Impact Assessment | Evaluation of design conflicts and retention feasibility. |
| 4. Mitigation Strategy | Foundation advice, protection measures and design adjustments (if needed). |
| 5. Reporting | A clear, BS 5837-compliant report ready for submission. |
We keep guidance clear and planning-ready — supporting predictable project delivery.
Our Approach
Practical Mitigation
Foundation options, construction routes and protection measures built around real site conditions.
Design Aligned
Clear explanations of how tree constraints interact with the proposal.
Planning Led
Reports structured for direct LPA interpretation
Technical Clarity
Evidence presented cleanly, without ambiguity.
Do I Need an AIA?
You may need an AIA if:
- your layout falls within any RPA
- access routes pass near trees
- designs include new hard surfaces, levels changes or foundations close to trees
- shading or overhang affects proposed rooms or gardens
- you’re planning new utilities, drainage or service runs
- planners request BS 5837 evidence
- your architect highlights tree constraints
- your PEA has already flagged arboricultural considerations
An AIA clarifies design impacts and prevents late-stage planning queries.
Why this Matters for Planning
Tree constraints are a formal material consideration under the Town & Country Planning Act 1990 and BS 5837.
LPAs expect:
- clear mapping of constraints
- justification for removals
- practical mitigation where conflicts occur
- predictable construction methodology
- retention aligned with site use and long-term pressure
Weak evidence leads to validation delays, redesign requests or planning conditions tied to tree protection.
Case Note
Your Next Step
Need an invertebrate survey? We’ll confirm what’s required and align survey windows with your programme.
Phone: 0800 494 7479
Email: [email protected]
AIA Survey FAQs
Can we build within a Root Protection Area?
Sometimes. It depends on the depth, method and impact. Alternative foundation designs may be acceptable.
Do all trees need to be retained?
No. Retention depends on category, condition, value and planning context.
Is an AIA required for small extensions?
If the works interact with RPAs or crown spread, planners often request one.
Can we redesign after the AIA?
Yes. Findings often guide practical adjustments early enough to avoid delays.
Will this delay planning?
Clear AIA evidence prevents validation issues and reduces LPA queries.
What if the design conflicts with a tree?
Mitigation may resolve it. If not, justified removal may be supported where evidence is clear.
Can shading affect planning approval?
Yes. Planners often consider light levels for proposed rooms and gardens.
Do I need an AIA and a tree survey?
Yes. The AIA interprets impacts; the tree survey provides baseline data.
Is a TPP always required?
Only where development interacts with retained trees.
What information do you need?
Site plan, layout, access routes and any existing surveys.
