Refused over trees: root protection and appeal evidence

Refused planning trees cases nearly always come down to one of three findings: the development would encroach into a root protection area, the tree would be lost or made unsafe, or the council had too little information to be satisfied either way. The third is the most common and the easiest to answer, because it is a gap in evidence rather than a conflict of judgement. An appeal that arrives with a BS 5837 survey, a tree protection plan, an arboricultural method statement and a foundation design usually deals with it.

What the refusal turns on

Read the reason for refusal and place it in one of four categories.

Encroachment means the built form, the foundations, the drainage runs or the construction access fall inside the root protection area of a retained tree. Direct loss means the scheme requires felling, and the argument moves to amenity value and replacement. Future pressure means the officer accepts the tree can be retained physically but expects the occupiers to demand heavy pruning or removal because of shade, leaf fall or perceived risk. Inadequate information means no arboricultural assessment was submitted, or one was submitted without the drawings that make it usable.

Each needs a different answer, and an appeal that treats all four as one argument about how much the applicant values the tree will not land.

The root protection area, and how it is calculated

BS 5837:2012, Trees in relation to design, demolition and construction, sets the method. For a single-stem tree the root protection area is the area of a circle whose radius is twelve times the stem diameter measured at 1.5m above ground level, capped at 707 square metres.

That cap matters on mature trees. A 1,200mm diameter oak would otherwise generate a radius of more than fourteen metres, and the cap holds the area at the equivalent of a fifteen metre radius. Multi-stem trees use a different stem diameter calculation, set out in the standard.

The standard also requires trees to be categorised. Category U trees are in such poor condition that they should be removed regardless of development. Category A, B and C trees are of high, moderate and low quality respectively, and the category drives how much weight retention carries. An appeal that seeks to remove a category C tree of limited amenity value is in a very different position from one affecting a category A specimen, and the survey should say so plainly rather than leaving the inspector to infer it.

Our explainer on the BS 5837 root protection area circle sets out the geometry, and root protection area calculations in an arboricultural impact assessment works through the arithmetic on real stem diameters.

Where the area can be reshaped

The point most refusals miss is that the root protection area is an area, not necessarily a circle.

BS 5837 allows the shape to be modified where soil conditions, existing structures, or the presence of hard surfacing mean rooting is unlikely to follow the circle, provided the total area is retained and the modified shape reflects where roots are actually likely to be. A tree growing hard against an existing building has no roots under that building, so the area can be offset away from it.

That single argument saves a great many schemes. It has to be made by an arboriculturist, with reasoning, on a drawing. Asserting the offset without explaining the physical basis for it is worse than not asserting it, because it looks like the survey was written to fit the layout.

Proving where the roots are

Where the offset argument is contested, the answer is investigation rather than debate.

Trial trenching under arboricultural supervision, or excavation with an air spade so roots are exposed without damage, shows what is actually present. The record is a plan of root positions and diameters, with photographs and a note of the soil profile. It costs a fraction of a redesign, and it converts an argument about probability into a set of observations.

Do it in a suitable season and with the tree owner's consent, and where the tree is protected by a Tree Preservation Order, check whether the investigation itself needs consent. Reporting an investigation that damaged roots would obviously undo the point.

The findings belong in an Arboricultural Impact Assessment, alongside the tree survey schedule, the tree constraints plan and the tree protection plan.

Foundations and no-dig construction

Where the built form has to sit within the root protection area, the design has to remove the harm rather than accept it.

• Pile and beam or screw pile foundations, with the beam clear of the ground, minimising excavation volume.
• Three-dimensional cellular confinement systems laid over a geotextile on the existing ground level for driveways and paths, with no reduced level dig.
• Suspended or permeable surfacing rather than a bound layer over the rooting zone.
• Drainage routed outside the area, or installed by directional drilling below the rooting depth.
• Ground protection during construction, with the specification and installation sequence drawn rather than described.

Every one of those is a detail the inspector can see on a drawing, and every one can be secured by condition. Offering the condition wording yourself, with the method statement it refers to, tends to be more persuasive than leaving the authority to invent it.

Answering the future pressure argument

Future pressure is a real planning consideration and it is often argued badly on both sides.

The evidence that answers it is a shade analysis showing sun paths across the proposed windows and gardens at the equinox and at midsummer and midwinter, together with the internal daylight position for the affected rooms. Where the analysis shows acceptable conditions, the argument that occupiers will demand felling loses its footing.

Layout helps as much as calculation. Putting habitable rooms and private amenity space away from the canopy, and locating parking or utility space under it, removes the conflict rather than mitigating it. So does a management plan setting out a cyclical pruning regime that keeps the tree at a size the site can accommodate.

What to submit with the appeal

1. A tree survey to BS 5837:2012 with the schedule, categories and a plan.
2. A tree constraints plan showing root protection areas, including any modified shape with the reasoning.
3. Root investigation findings where the shape is contested.
4. A tree protection plan and an arboricultural method statement, with the protective fencing specification.
5. Foundation and surfacing details for anything within the rooting zone.
6. Shade analysis where future pressure is a reason for refusal.
7. Replacement planting proposals, with species, size and a five-year maintenance commitment.

Offer arboricultural supervision at defined stages as a condition. It reassures the inspector that the method statement will be followed, and it costs little.

If the tree is protected, remember that works to it need separate consent under the Tree Preservation Order regulations, and that trees in a conservation area require six weeks' written notice to the authority. Our guide to extending near a protected tree covers that procedure.

This is general guidance rather than legal advice. Check the position with your local planning authority, the tree officer or a qualified arboriculturist before relying on it.

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